[PATCH] kfree cleanup: drivers/s390
[linux-2.6.git] / drivers / s390 / block / dasd.c
1 /*
2  * File...........: linux/drivers/s390/block/dasd.c
3  * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
4  *                  Horst Hummel <Horst.Hummel@de.ibm.com>
5  *                  Carsten Otte <Cotte@de.ibm.com>
6  *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
7  * Bugreports.to..: <Linux390@de.ibm.com>
8  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
9  *
10  * $Revision: 1.167 $
11  */
12
13 #include <linux/config.h>
14 #include <linux/kmod.h>
15 #include <linux/init.h>
16 #include <linux/interrupt.h>
17 #include <linux/ctype.h>
18 #include <linux/major.h>
19 #include <linux/slab.h>
20 #include <linux/buffer_head.h>
21
22 #include <asm/ccwdev.h>
23 #include <asm/ebcdic.h>
24 #include <asm/idals.h>
25 #include <asm/todclk.h>
26
27 /* This is ugly... */
28 #define PRINTK_HEADER "dasd:"
29
30 #include "dasd_int.h"
31 /*
32  * SECTION: Constant definitions to be used within this file
33  */
34 #define DASD_CHANQ_MAX_SIZE 4
35
36 /*
37  * SECTION: exported variables of dasd.c
38  */
39 debug_info_t *dasd_debug_area;
40 struct dasd_discipline *dasd_diag_discipline_pointer;
41
42 MODULE_AUTHOR("Holger Smolinski <Holger.Smolinski@de.ibm.com>");
43 MODULE_DESCRIPTION("Linux on S/390 DASD device driver,"
44                    " Copyright 2000 IBM Corporation");
45 MODULE_SUPPORTED_DEVICE("dasd");
46 MODULE_PARM(dasd, "1-" __MODULE_STRING(256) "s");
47 MODULE_LICENSE("GPL");
48
49 /*
50  * SECTION: prototypes for static functions of dasd.c
51  */
52 static int  dasd_alloc_queue(struct dasd_device * device);
53 static void dasd_setup_queue(struct dasd_device * device);
54 static void dasd_free_queue(struct dasd_device * device);
55 static void dasd_flush_request_queue(struct dasd_device *);
56 static void dasd_int_handler(struct ccw_device *, unsigned long, struct irb *);
57 static void dasd_flush_ccw_queue(struct dasd_device *, int);
58 static void dasd_tasklet(struct dasd_device *);
59 static void do_kick_device(void *data);
60
61 /*
62  * SECTION: Operations on the device structure.
63  */
64 static wait_queue_head_t dasd_init_waitq;
65
66 /*
67  * Allocate memory for a new device structure.
68  */
69 struct dasd_device *
70 dasd_alloc_device(void)
71 {
72         struct dasd_device *device;
73
74         device = kmalloc(sizeof (struct dasd_device), GFP_ATOMIC);
75         if (device == NULL)
76                 return ERR_PTR(-ENOMEM);
77         memset(device, 0, sizeof (struct dasd_device));
78         /* open_count = 0 means device online but not in use */
79         atomic_set(&device->open_count, -1);
80
81         /* Get two pages for normal block device operations. */
82         device->ccw_mem = (void *) __get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
83         if (device->ccw_mem == NULL) {
84                 kfree(device);
85                 return ERR_PTR(-ENOMEM);
86         }
87         /* Get one page for error recovery. */
88         device->erp_mem = (void *) get_zeroed_page(GFP_ATOMIC | GFP_DMA);
89         if (device->erp_mem == NULL) {
90                 free_pages((unsigned long) device->ccw_mem, 1);
91                 kfree(device);
92                 return ERR_PTR(-ENOMEM);
93         }
94
95         dasd_init_chunklist(&device->ccw_chunks, device->ccw_mem, PAGE_SIZE*2);
96         dasd_init_chunklist(&device->erp_chunks, device->erp_mem, PAGE_SIZE);
97         spin_lock_init(&device->mem_lock);
98         spin_lock_init(&device->request_queue_lock);
99         atomic_set (&device->tasklet_scheduled, 0);
100         tasklet_init(&device->tasklet, 
101                      (void (*)(unsigned long)) dasd_tasklet,
102                      (unsigned long) device);
103         INIT_LIST_HEAD(&device->ccw_queue);
104         init_timer(&device->timer);
105         INIT_WORK(&device->kick_work, do_kick_device, device);
106         device->state = DASD_STATE_NEW;
107         device->target = DASD_STATE_NEW;
108
109         return device;
110 }
111
112 /*
113  * Free memory of a device structure.
114  */
115 void
116 dasd_free_device(struct dasd_device *device)
117 {
118         kfree(device->private);
119         free_page((unsigned long) device->erp_mem);
120         free_pages((unsigned long) device->ccw_mem, 1);
121         kfree(device);
122 }
123
124 /*
125  * Make a new device known to the system.
126  */
127 static inline int
128 dasd_state_new_to_known(struct dasd_device *device)
129 {
130         int rc;
131
132         /*
133          * As long as the device is not in state DASD_STATE_NEW we want to 
134          * keep the reference count > 0.
135          */
136         dasd_get_device(device);
137
138         rc = dasd_alloc_queue(device);
139         if (rc) {
140                 dasd_put_device(device);
141                 return rc;
142         }
143
144         device->state = DASD_STATE_KNOWN;
145         return 0;
146 }
147
148 /*
149  * Let the system forget about a device.
150  */
151 static inline void
152 dasd_state_known_to_new(struct dasd_device * device)
153 {
154         /* Forget the discipline information. */
155         device->discipline = NULL;
156         device->state = DASD_STATE_NEW;
157
158         dasd_free_queue(device);
159
160         /* Give up reference we took in dasd_state_new_to_known. */
161         dasd_put_device(device);
162 }
163
164 /*
165  * Request the irq line for the device.
166  */
167 static inline int
168 dasd_state_known_to_basic(struct dasd_device * device)
169 {
170         int rc;
171
172         /* Allocate and register gendisk structure. */
173         rc = dasd_gendisk_alloc(device);
174         if (rc)
175                 return rc;
176
177         /* register 'device' debug area, used for all DBF_DEV_XXX calls */
178         device->debug_area = debug_register(device->cdev->dev.bus_id, 1, 2,
179                                             8 * sizeof (long));
180         debug_register_view(device->debug_area, &debug_sprintf_view);
181         debug_set_level(device->debug_area, DBF_EMERG);
182         DBF_DEV_EVENT(DBF_EMERG, device, "%s", "debug area created");
183
184         device->state = DASD_STATE_BASIC;
185         return 0;
186 }
187
188 /*
189  * Release the irq line for the device. Terminate any running i/o.
190  */
191 static inline void
192 dasd_state_basic_to_known(struct dasd_device * device)
193 {
194         dasd_gendisk_free(device);
195         dasd_flush_ccw_queue(device, 1);
196         DBF_DEV_EVENT(DBF_EMERG, device, "%p debug area deleted", device);
197         if (device->debug_area != NULL) {
198                 debug_unregister(device->debug_area);
199                 device->debug_area = NULL;
200         }
201         device->state = DASD_STATE_KNOWN;
202 }
203
204 /*
205  * Do the initial analysis. The do_analysis function may return
206  * -EAGAIN in which case the device keeps the state DASD_STATE_BASIC
207  * until the discipline decides to continue the startup sequence
208  * by calling the function dasd_change_state. The eckd disciplines
209  * uses this to start a ccw that detects the format. The completion
210  * interrupt for this detection ccw uses the kernel event daemon to
211  * trigger the call to dasd_change_state. All this is done in the
212  * discipline code, see dasd_eckd.c.
213  * After the analysis ccw is done (do_analysis returned 0 or error)
214  * the block device is setup. Either a fake disk is added to allow
215  * formatting or a proper device request queue is created.
216  */
217 static inline int
218 dasd_state_basic_to_ready(struct dasd_device * device)
219 {
220         int rc;
221
222         rc = 0;
223         if (device->discipline->do_analysis != NULL)
224                 rc = device->discipline->do_analysis(device);
225         if (rc)
226                 return rc;
227         dasd_setup_queue(device);
228         device->state = DASD_STATE_READY;
229         if (dasd_scan_partitions(device) != 0)
230                 device->state = DASD_STATE_BASIC;
231         return 0;
232 }
233
234 /*
235  * Remove device from block device layer. Destroy dirty buffers.
236  * Forget format information. Check if the target level is basic
237  * and if it is create fake disk for formatting.
238  */
239 static inline void
240 dasd_state_ready_to_basic(struct dasd_device * device)
241 {
242         dasd_flush_ccw_queue(device, 0);
243         dasd_destroy_partitions(device);
244         dasd_flush_request_queue(device);
245         device->blocks = 0;
246         device->bp_block = 0;
247         device->s2b_shift = 0;
248         device->state = DASD_STATE_BASIC;
249 }
250
251 /*
252  * Make the device online and schedule the bottom half to start
253  * the requeueing of requests from the linux request queue to the
254  * ccw queue.
255  */
256 static inline int
257 dasd_state_ready_to_online(struct dasd_device * device)
258 {
259         device->state = DASD_STATE_ONLINE;
260         dasd_schedule_bh(device);
261         return 0;
262 }
263
264 /*
265  * Stop the requeueing of requests again.
266  */
267 static inline void
268 dasd_state_online_to_ready(struct dasd_device * device)
269 {
270         device->state = DASD_STATE_READY;
271 }
272
273 /*
274  * Device startup state changes.
275  */
276 static inline int
277 dasd_increase_state(struct dasd_device *device)
278 {
279         int rc;
280
281         rc = 0;
282         if (device->state == DASD_STATE_NEW &&
283             device->target >= DASD_STATE_KNOWN)
284                 rc = dasd_state_new_to_known(device);
285
286         if (!rc &&
287             device->state == DASD_STATE_KNOWN &&
288             device->target >= DASD_STATE_BASIC)
289                 rc = dasd_state_known_to_basic(device);
290
291         if (!rc &&
292             device->state == DASD_STATE_BASIC &&
293             device->target >= DASD_STATE_READY)
294                 rc = dasd_state_basic_to_ready(device);
295
296         if (!rc &&
297             device->state == DASD_STATE_READY &&
298             device->target >= DASD_STATE_ONLINE)
299                 rc = dasd_state_ready_to_online(device);
300
301         return rc;
302 }
303
304 /*
305  * Device shutdown state changes.
306  */
307 static inline int
308 dasd_decrease_state(struct dasd_device *device)
309 {
310         if (device->state == DASD_STATE_ONLINE &&
311             device->target <= DASD_STATE_READY)
312                 dasd_state_online_to_ready(device);
313         
314         if (device->state == DASD_STATE_READY &&
315             device->target <= DASD_STATE_BASIC)
316                 dasd_state_ready_to_basic(device);
317         
318         if (device->state == DASD_STATE_BASIC && 
319             device->target <= DASD_STATE_KNOWN)
320                 dasd_state_basic_to_known(device);
321         
322         if (device->state == DASD_STATE_KNOWN &&
323             device->target <= DASD_STATE_NEW)
324                 dasd_state_known_to_new(device);
325
326         return 0;
327 }
328
329 /*
330  * This is the main startup/shutdown routine.
331  */
332 static void
333 dasd_change_state(struct dasd_device *device)
334 {
335         int rc;
336
337         if (device->state == device->target)
338                 /* Already where we want to go today... */
339                 return;
340         if (device->state < device->target)
341                 rc = dasd_increase_state(device);
342         else
343                 rc = dasd_decrease_state(device);
344         if (rc && rc != -EAGAIN)
345                 device->target = device->state;
346
347         if (device->state == device->target)
348                 wake_up(&dasd_init_waitq);
349 }
350
351 /*
352  * Kick starter for devices that did not complete the startup/shutdown
353  * procedure or were sleeping because of a pending state.
354  * dasd_kick_device will schedule a call do do_kick_device to the kernel
355  * event daemon.
356  */
357 static void
358 do_kick_device(void *data)
359 {
360         struct dasd_device *device;
361
362         device = (struct dasd_device *) data;
363         dasd_change_state(device);
364         dasd_schedule_bh(device);
365         dasd_put_device(device);
366 }
367
368 void
369 dasd_kick_device(struct dasd_device *device)
370 {
371         dasd_get_device(device);
372         /* queue call to dasd_kick_device to the kernel event daemon. */
373         schedule_work(&device->kick_work);
374 }
375
376 /*
377  * Set the target state for a device and starts the state change.
378  */
379 void
380 dasd_set_target_state(struct dasd_device *device, int target)
381 {
382         /* If we are in probeonly mode stop at DASD_STATE_READY. */
383         if (dasd_probeonly && target > DASD_STATE_READY)
384                 target = DASD_STATE_READY;
385         if (device->target != target) {
386                 if (device->state == target)
387                         wake_up(&dasd_init_waitq);
388                 device->target = target;
389         }
390         if (device->state != device->target)
391                 dasd_change_state(device);
392 }
393
394 /*
395  * Enable devices with device numbers in [from..to].
396  */
397 static inline int
398 _wait_for_device(struct dasd_device *device)
399 {
400         return (device->state == device->target);
401 }
402
403 void
404 dasd_enable_device(struct dasd_device *device)
405 {
406         dasd_set_target_state(device, DASD_STATE_ONLINE);
407         if (device->state <= DASD_STATE_KNOWN)
408                 /* No discipline for device found. */
409                 dasd_set_target_state(device, DASD_STATE_NEW);
410         /* Now wait for the devices to come up. */
411         wait_event(dasd_init_waitq, _wait_for_device(device));
412 }
413
414 /*
415  * SECTION: device operation (interrupt handler, start i/o, term i/o ...)
416  */
417 #ifdef CONFIG_DASD_PROFILE
418
419 struct dasd_profile_info_t dasd_global_profile;
420 unsigned int dasd_profile_level = DASD_PROFILE_OFF;
421
422 /*
423  * Increments counter in global and local profiling structures.
424  */
425 #define dasd_profile_counter(value, counter, device) \
426 { \
427         int index; \
428         for (index = 0; index < 31 && value >> (2+index); index++); \
429         dasd_global_profile.counter[index]++; \
430         device->profile.counter[index]++; \
431 }
432
433 /*
434  * Add profiling information for cqr before execution.
435  */
436 static inline void
437 dasd_profile_start(struct dasd_device *device, struct dasd_ccw_req * cqr,
438                    struct request *req)
439 {
440         struct list_head *l;
441         unsigned int counter;
442
443         if (dasd_profile_level != DASD_PROFILE_ON)
444                 return;
445
446         /* count the length of the chanq for statistics */
447         counter = 0;
448         list_for_each(l, &device->ccw_queue)
449                 if (++counter >= 31)
450                         break;
451         dasd_global_profile.dasd_io_nr_req[counter]++;
452         device->profile.dasd_io_nr_req[counter]++;
453 }
454
455 /*
456  * Add profiling information for cqr after execution.
457  */
458 static inline void
459 dasd_profile_end(struct dasd_device *device, struct dasd_ccw_req * cqr,
460                  struct request *req)
461 {
462         long strtime, irqtime, endtime, tottime;        /* in microseconds */
463         long tottimeps, sectors;
464
465         if (dasd_profile_level != DASD_PROFILE_ON)
466                 return;
467
468         sectors = req->nr_sectors;
469         if (!cqr->buildclk || !cqr->startclk ||
470             !cqr->stopclk || !cqr->endclk ||
471             !sectors)
472                 return;
473
474         strtime = ((cqr->startclk - cqr->buildclk) >> 12);
475         irqtime = ((cqr->stopclk - cqr->startclk) >> 12);
476         endtime = ((cqr->endclk - cqr->stopclk) >> 12);
477         tottime = ((cqr->endclk - cqr->buildclk) >> 12);
478         tottimeps = tottime / sectors;
479
480         if (!dasd_global_profile.dasd_io_reqs)
481                 memset(&dasd_global_profile, 0,
482                        sizeof (struct dasd_profile_info_t));
483         dasd_global_profile.dasd_io_reqs++;
484         dasd_global_profile.dasd_io_sects += sectors;
485
486         if (!device->profile.dasd_io_reqs)
487                 memset(&device->profile, 0,
488                        sizeof (struct dasd_profile_info_t));
489         device->profile.dasd_io_reqs++;
490         device->profile.dasd_io_sects += sectors;
491
492         dasd_profile_counter(sectors, dasd_io_secs, device);
493         dasd_profile_counter(tottime, dasd_io_times, device);
494         dasd_profile_counter(tottimeps, dasd_io_timps, device);
495         dasd_profile_counter(strtime, dasd_io_time1, device);
496         dasd_profile_counter(irqtime, dasd_io_time2, device);
497         dasd_profile_counter(irqtime / sectors, dasd_io_time2ps, device);
498         dasd_profile_counter(endtime, dasd_io_time3, device);
499 }
500 #else
501 #define dasd_profile_start(device, cqr, req) do {} while (0)
502 #define dasd_profile_end(device, cqr, req) do {} while (0)
503 #endif                          /* CONFIG_DASD_PROFILE */
504
505 /*
506  * Allocate memory for a channel program with 'cplength' channel
507  * command words and 'datasize' additional space. There are two
508  * variantes: 1) dasd_kmalloc_request uses kmalloc to get the needed
509  * memory and 2) dasd_smalloc_request uses the static ccw memory
510  * that gets allocated for each device.
511  */
512 struct dasd_ccw_req *
513 dasd_kmalloc_request(char *magic, int cplength, int datasize,
514                    struct dasd_device * device)
515 {
516         struct dasd_ccw_req *cqr;
517
518         /* Sanity checks */
519         if ( magic == NULL || datasize > PAGE_SIZE ||
520              (cplength*sizeof(struct ccw1)) > PAGE_SIZE)
521                 BUG();
522
523         cqr = kmalloc(sizeof(struct dasd_ccw_req), GFP_ATOMIC);
524         if (cqr == NULL)
525                 return ERR_PTR(-ENOMEM);
526         memset(cqr, 0, sizeof(struct dasd_ccw_req));
527         cqr->cpaddr = NULL;
528         if (cplength > 0) {
529                 cqr->cpaddr = kmalloc(cplength*sizeof(struct ccw1),
530                                       GFP_ATOMIC | GFP_DMA);
531                 if (cqr->cpaddr == NULL) {
532                         kfree(cqr);
533                         return ERR_PTR(-ENOMEM);
534                 }
535                 memset(cqr->cpaddr, 0, cplength*sizeof(struct ccw1));
536         }
537         cqr->data = NULL;
538         if (datasize > 0) {
539                 cqr->data = kmalloc(datasize, GFP_ATOMIC | GFP_DMA);
540                 if (cqr->data == NULL) {
541                         kfree(cqr->cpaddr);
542                         kfree(cqr);
543                         return ERR_PTR(-ENOMEM);
544                 }
545                 memset(cqr->data, 0, datasize);
546         }
547         strncpy((char *) &cqr->magic, magic, 4);
548         ASCEBC((char *) &cqr->magic, 4);
549         set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
550         dasd_get_device(device);
551         return cqr;
552 }
553
554 struct dasd_ccw_req *
555 dasd_smalloc_request(char *magic, int cplength, int datasize,
556                    struct dasd_device * device)
557 {
558         unsigned long flags;
559         struct dasd_ccw_req *cqr;
560         char *data;
561         int size;
562
563         /* Sanity checks */
564         if ( magic == NULL || datasize > PAGE_SIZE ||
565              (cplength*sizeof(struct ccw1)) > PAGE_SIZE)
566                 BUG();
567
568         size = (sizeof(struct dasd_ccw_req) + 7L) & -8L;
569         if (cplength > 0)
570                 size += cplength * sizeof(struct ccw1);
571         if (datasize > 0)
572                 size += datasize;
573         spin_lock_irqsave(&device->mem_lock, flags);
574         cqr = (struct dasd_ccw_req *)
575                 dasd_alloc_chunk(&device->ccw_chunks, size);
576         spin_unlock_irqrestore(&device->mem_lock, flags);
577         if (cqr == NULL)
578                 return ERR_PTR(-ENOMEM);
579         memset(cqr, 0, sizeof(struct dasd_ccw_req));
580         data = (char *) cqr + ((sizeof(struct dasd_ccw_req) + 7L) & -8L);
581         cqr->cpaddr = NULL;
582         if (cplength > 0) {
583                 cqr->cpaddr = (struct ccw1 *) data;
584                 data += cplength*sizeof(struct ccw1);
585                 memset(cqr->cpaddr, 0, cplength*sizeof(struct ccw1));
586         }
587         cqr->data = NULL;
588         if (datasize > 0) {
589                 cqr->data = data;
590                 memset(cqr->data, 0, datasize);
591         }
592         strncpy((char *) &cqr->magic, magic, 4);
593         ASCEBC((char *) &cqr->magic, 4);
594         set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
595         dasd_get_device(device);
596         return cqr;
597 }
598
599 /*
600  * Free memory of a channel program. This function needs to free all the
601  * idal lists that might have been created by dasd_set_cda and the
602  * struct dasd_ccw_req itself.
603  */
604 void
605 dasd_kfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
606 {
607 #ifdef CONFIG_ARCH_S390X
608         struct ccw1 *ccw;
609
610         /* Clear any idals used for the request. */
611         ccw = cqr->cpaddr;
612         do {
613                 clear_normalized_cda(ccw);
614         } while (ccw++->flags & (CCW_FLAG_CC | CCW_FLAG_DC));
615 #endif
616         kfree(cqr->cpaddr);
617         kfree(cqr->data);
618         kfree(cqr);
619         dasd_put_device(device);
620 }
621
622 void
623 dasd_sfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
624 {
625         unsigned long flags;
626
627         spin_lock_irqsave(&device->mem_lock, flags);
628         dasd_free_chunk(&device->ccw_chunks, cqr);
629         spin_unlock_irqrestore(&device->mem_lock, flags);
630         dasd_put_device(device);
631 }
632
633 /*
634  * Check discipline magic in cqr.
635  */
636 static inline int
637 dasd_check_cqr(struct dasd_ccw_req *cqr)
638 {
639         struct dasd_device *device;
640
641         if (cqr == NULL)
642                 return -EINVAL;
643         device = cqr->device;
644         if (strncmp((char *) &cqr->magic, device->discipline->ebcname, 4)) {
645                 DEV_MESSAGE(KERN_WARNING, device,
646                             " dasd_ccw_req 0x%08x magic doesn't match"
647                             " discipline 0x%08x",
648                             cqr->magic,
649                             *(unsigned int *) device->discipline->name);
650                 return -EINVAL;
651         }
652         return 0;
653 }
654
655 /*
656  * Terminate the current i/o and set the request to clear_pending.
657  * Timer keeps device runnig.
658  * ccw_device_clear can fail if the i/o subsystem
659  * is in a bad mood.
660  */
661 int
662 dasd_term_IO(struct dasd_ccw_req * cqr)
663 {
664         struct dasd_device *device;
665         int retries, rc;
666
667         /* Check the cqr */
668         rc = dasd_check_cqr(cqr);
669         if (rc)
670                 return rc;
671         retries = 0;
672         device = (struct dasd_device *) cqr->device;
673         while ((retries < 5) && (cqr->status == DASD_CQR_IN_IO)) {
674                 rc = ccw_device_clear(device->cdev, (long) cqr);
675                 switch (rc) {
676                 case 0: /* termination successful */
677                         if (cqr->retries > 0) {
678                                 cqr->retries--;
679                                 cqr->status = DASD_CQR_CLEAR;
680                         } else
681                                 cqr->status = DASD_CQR_FAILED;
682                         cqr->stopclk = get_clock();
683                         DBF_DEV_EVENT(DBF_DEBUG, device,
684                                       "terminate cqr %p successful",
685                                       cqr);
686                         break;
687                 case -ENODEV:
688                         DBF_DEV_EVENT(DBF_ERR, device, "%s",
689                                       "device gone, retry");
690                         break;
691                 case -EIO:
692                         DBF_DEV_EVENT(DBF_ERR, device, "%s",
693                                       "I/O error, retry");
694                         break;
695                 case -EINVAL:
696                 case -EBUSY:
697                         DBF_DEV_EVENT(DBF_ERR, device, "%s",
698                                       "device busy, retry later");
699                         break;
700                 default:
701                         DEV_MESSAGE(KERN_ERR, device,
702                                     "line %d unknown RC=%d, please "
703                                     "report to linux390@de.ibm.com",
704                                     __LINE__, rc);
705                         BUG();
706                         break;
707                 }
708                 retries++;
709         }
710         dasd_schedule_bh(device);
711         return rc;
712 }
713
714 /*
715  * Start the i/o. This start_IO can fail if the channel is really busy.
716  * In that case set up a timer to start the request later.
717  */
718 int
719 dasd_start_IO(struct dasd_ccw_req * cqr)
720 {
721         struct dasd_device *device;
722         int rc;
723
724         /* Check the cqr */
725         rc = dasd_check_cqr(cqr);
726         if (rc)
727                 return rc;
728         device = (struct dasd_device *) cqr->device;
729         if (cqr->retries < 0) {
730                 DEV_MESSAGE(KERN_DEBUG, device,
731                             "start_IO: request %p (%02x/%i) - no retry left.",
732                             cqr, cqr->status, cqr->retries);
733                 cqr->status = DASD_CQR_FAILED;
734                 return -EIO;
735         }
736         cqr->startclk = get_clock();
737         cqr->starttime = jiffies;
738         cqr->retries--;
739         rc = ccw_device_start(device->cdev, cqr->cpaddr, (long) cqr,
740                               cqr->lpm, 0);
741         switch (rc) {
742         case 0:
743                 cqr->status = DASD_CQR_IN_IO;
744                 DBF_DEV_EVENT(DBF_DEBUG, device,
745                               "start_IO: request %p started successful",
746                               cqr);
747                 break;
748         case -EBUSY:
749                 DBF_DEV_EVENT(DBF_ERR, device, "%s",
750                               "start_IO: device busy, retry later");
751                 break;
752         case -ETIMEDOUT:
753                 DBF_DEV_EVENT(DBF_ERR, device, "%s",
754                               "start_IO: request timeout, retry later");
755                 break;
756         case -EACCES:
757                 /* -EACCES indicates that the request used only a
758                  * subset of the available pathes and all these
759                  * pathes are gone.
760                  * Do a retry with all available pathes.
761                  */
762                 cqr->lpm = LPM_ANYPATH;
763                 DBF_DEV_EVENT(DBF_ERR, device, "%s",
764                               "start_IO: selected pathes gone,"
765                               " retry on all pathes");
766                 break;
767         case -ENODEV:
768         case -EIO:
769                 DBF_DEV_EVENT(DBF_ERR, device, "%s",
770                               "start_IO: device gone, retry");
771                 break;
772         default:
773                 DEV_MESSAGE(KERN_ERR, device,
774                             "line %d unknown RC=%d, please report"
775                             " to linux390@de.ibm.com", __LINE__, rc);
776                 BUG();
777                 break;
778         }
779         return rc;
780 }
781
782 /*
783  * Timeout function for dasd devices. This is used for different purposes
784  *  1) missing interrupt handler for normal operation
785  *  2) delayed start of request where start_IO failed with -EBUSY
786  *  3) timeout for missing state change interrupts
787  * The head of the ccw queue will have status DASD_CQR_IN_IO for 1),
788  * DASD_CQR_QUEUED for 2) and 3).
789  */
790 static void
791 dasd_timeout_device(unsigned long ptr)
792 {
793         unsigned long flags;
794         struct dasd_device *device;
795
796         device = (struct dasd_device *) ptr;
797         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
798         /* re-activate request queue */
799         device->stopped &= ~DASD_STOPPED_PENDING;
800         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
801         dasd_schedule_bh(device);
802 }
803
804 /*
805  * Setup timeout for a device in jiffies.
806  */
807 void
808 dasd_set_timer(struct dasd_device *device, int expires)
809 {
810         if (expires == 0) {
811                 if (timer_pending(&device->timer))
812                         del_timer(&device->timer);
813                 return;
814         }
815         if (timer_pending(&device->timer)) {
816                 if (mod_timer(&device->timer, jiffies + expires))
817                         return;
818         }
819         device->timer.function = dasd_timeout_device;
820         device->timer.data = (unsigned long) device;
821         device->timer.expires = jiffies + expires;
822         add_timer(&device->timer);
823 }
824
825 /*
826  * Clear timeout for a device.
827  */
828 void
829 dasd_clear_timer(struct dasd_device *device)
830 {
831         if (timer_pending(&device->timer))
832                 del_timer(&device->timer);
833 }
834
835 static void
836 dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
837 {
838         struct dasd_ccw_req *cqr;
839         struct dasd_device *device;
840
841         cqr = (struct dasd_ccw_req *) intparm;
842         if (cqr->status != DASD_CQR_IN_IO) {
843                 MESSAGE(KERN_DEBUG,
844                         "invalid status in handle_killed_request: "
845                         "bus_id %s, status %02x",
846                         cdev->dev.bus_id, cqr->status);
847                 return;
848         }
849
850         device = (struct dasd_device *) cqr->device;
851         if (device == NULL ||
852             device != dasd_device_from_cdev(cdev) ||
853             strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
854                 MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
855                         cdev->dev.bus_id);
856                 return;
857         }
858
859         /* Schedule request to be retried. */
860         cqr->status = DASD_CQR_QUEUED;
861
862         dasd_clear_timer(device);
863         dasd_schedule_bh(device);
864         dasd_put_device(device);
865 }
866
867 static void
868 dasd_handle_state_change_pending(struct dasd_device *device)
869 {
870         struct dasd_ccw_req *cqr;
871         struct list_head *l, *n;
872
873         device->stopped &= ~DASD_STOPPED_PENDING;
874
875         /* restart all 'running' IO on queue */
876         list_for_each_safe(l, n, &device->ccw_queue) {
877                 cqr = list_entry(l, struct dasd_ccw_req, list);
878                 if (cqr->status == DASD_CQR_IN_IO) {
879                         cqr->status = DASD_CQR_QUEUED;
880                 }
881         }
882         dasd_clear_timer(device);
883         dasd_schedule_bh(device);
884 }
885
886 /*
887  * Interrupt handler for "normal" ssch-io based dasd devices.
888  */
889 void
890 dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
891                  struct irb *irb)
892 {
893         struct dasd_ccw_req *cqr, *next;
894         struct dasd_device *device;
895         unsigned long long now;
896         int expires;
897         dasd_era_t era;
898         char mask;
899
900         if (IS_ERR(irb)) {
901                 switch (PTR_ERR(irb)) {
902                 case -EIO:
903                         dasd_handle_killed_request(cdev, intparm);
904                         break;
905                 case -ETIMEDOUT:
906                         printk(KERN_WARNING"%s(%s): request timed out\n",
907                                __FUNCTION__, cdev->dev.bus_id);
908                         //FIXME - dasd uses own timeout interface...
909                         break;
910                 default:
911                         printk(KERN_WARNING"%s(%s): unknown error %ld\n",
912                                __FUNCTION__, cdev->dev.bus_id, PTR_ERR(irb));
913                 }
914                 return;
915         }
916
917         now = get_clock();
918
919         DBF_EVENT(DBF_ERR, "Interrupt: bus_id %s CS/DS %04x ip %08x",
920                   cdev->dev.bus_id, ((irb->scsw.cstat<<8)|irb->scsw.dstat),
921                   (unsigned int) intparm);
922
923         /* first of all check for state change pending interrupt */
924         mask = DEV_STAT_ATTENTION | DEV_STAT_DEV_END | DEV_STAT_UNIT_EXCEP;
925         if ((irb->scsw.dstat & mask) == mask) {
926                 device = dasd_device_from_cdev(cdev);
927                 if (!IS_ERR(device)) {
928                         dasd_handle_state_change_pending(device);
929                         dasd_put_device(device);
930                 }
931                 return;
932         }
933
934         cqr = (struct dasd_ccw_req *) intparm;
935
936         /* check for unsolicited interrupts */
937         if (cqr == NULL) {
938                 MESSAGE(KERN_DEBUG,
939                         "unsolicited interrupt received: bus_id %s",
940                         cdev->dev.bus_id);
941                 return;
942         }
943
944         device = (struct dasd_device *) cqr->device;
945         if (device == NULL ||
946             strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
947                 MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
948                         cdev->dev.bus_id);
949                 return;
950         }
951
952         /* Check for clear pending */
953         if (cqr->status == DASD_CQR_CLEAR &&
954             irb->scsw.fctl & SCSW_FCTL_CLEAR_FUNC) {
955                 cqr->status = DASD_CQR_QUEUED;
956                 dasd_clear_timer(device);
957                 dasd_schedule_bh(device);
958                 return;
959         }
960
961         /* check status - the request might have been killed by dyn detach */
962         if (cqr->status != DASD_CQR_IN_IO) {
963                 MESSAGE(KERN_DEBUG,
964                         "invalid status: bus_id %s, status %02x",
965                         cdev->dev.bus_id, cqr->status);
966                 return;
967         }
968         DBF_DEV_EVENT(DBF_DEBUG, device, "Int: CS/DS 0x%04x for cqr %p",
969                       ((irb->scsw.cstat << 8) | irb->scsw.dstat), cqr);
970
971         /* Find out the appropriate era_action. */
972         if (irb->scsw.fctl & SCSW_FCTL_HALT_FUNC) 
973                 era = dasd_era_fatal;
974         else if (irb->scsw.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
975                  irb->scsw.cstat == 0 &&
976                  !irb->esw.esw0.erw.cons)
977                 era = dasd_era_none;
978         else if (!test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags))
979                 era = dasd_era_fatal; /* don't recover this request */
980         else if (irb->esw.esw0.erw.cons)
981                 era = device->discipline->examine_error(cqr, irb);
982         else 
983                 era = dasd_era_recover;
984
985         DBF_DEV_EVENT(DBF_DEBUG, device, "era_code %d", era);
986         expires = 0;
987         if (era == dasd_era_none) {
988                 cqr->status = DASD_CQR_DONE;
989                 cqr->stopclk = now;
990                 /* Start first request on queue if possible -> fast_io. */
991                 if (cqr->list.next != &device->ccw_queue) {
992                         next = list_entry(cqr->list.next,
993                                           struct dasd_ccw_req, list);
994                         if ((next->status == DASD_CQR_QUEUED) &&
995                             (!device->stopped)) {
996                                 if (device->discipline->start_IO(next) == 0)
997                                         expires = next->expires;
998                                 else
999                                         DEV_MESSAGE(KERN_DEBUG, device, "%s",
1000                                                     "Interrupt fastpath "
1001                                                     "failed!");
1002                         }
1003                 }
1004         } else {                /* error */
1005                 memcpy(&cqr->irb, irb, sizeof (struct irb));
1006 #ifdef ERP_DEBUG
1007                 /* dump sense data */
1008                 dasd_log_sense(cqr, irb);
1009 #endif
1010                 switch (era) {
1011                 case dasd_era_fatal:
1012                         cqr->status = DASD_CQR_FAILED;
1013                         cqr->stopclk = now;
1014                         break;
1015                 case dasd_era_recover:
1016                         cqr->status = DASD_CQR_ERROR;
1017                         break;
1018                 default:
1019                         BUG();
1020                 }
1021         }
1022         if (expires != 0)
1023                 dasd_set_timer(device, expires);
1024         else
1025                 dasd_clear_timer(device);
1026         dasd_schedule_bh(device);
1027 }
1028
1029 /*
1030  * posts the buffer_cache about a finalized request
1031  */
1032 static inline void
1033 dasd_end_request(struct request *req, int uptodate)
1034 {
1035         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
1036                 BUG();
1037         add_disk_randomness(req->rq_disk);
1038         end_that_request_last(req);
1039 }
1040
1041 /*
1042  * Process finished error recovery ccw.
1043  */
1044 static inline void
1045 __dasd_process_erp(struct dasd_device *device, struct dasd_ccw_req *cqr)
1046 {
1047         dasd_erp_fn_t erp_fn;
1048
1049         if (cqr->status == DASD_CQR_DONE)
1050                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s", "ERP successful");
1051         else
1052                 DEV_MESSAGE(KERN_ERR, device, "%s", "ERP unsuccessful");
1053         erp_fn = device->discipline->erp_postaction(cqr);
1054         erp_fn(cqr);
1055 }
1056
1057 /*
1058  * Process ccw request queue.
1059  */
1060 static inline void
1061 __dasd_process_ccw_queue(struct dasd_device * device,
1062                          struct list_head *final_queue)
1063 {
1064         struct list_head *l, *n;
1065         struct dasd_ccw_req *cqr;
1066         dasd_erp_fn_t erp_fn;
1067
1068 restart:
1069         /* Process request with final status. */
1070         list_for_each_safe(l, n, &device->ccw_queue) {
1071                 cqr = list_entry(l, struct dasd_ccw_req, list);
1072                 /* Stop list processing at the first non-final request. */
1073                 if (cqr->status != DASD_CQR_DONE &&
1074                     cqr->status != DASD_CQR_FAILED &&
1075                     cqr->status != DASD_CQR_ERROR)
1076                         break;
1077                 /*  Process requests with DASD_CQR_ERROR */
1078                 if (cqr->status == DASD_CQR_ERROR) {
1079                         if (cqr->irb.scsw.fctl & SCSW_FCTL_HALT_FUNC) {
1080                                 cqr->status = DASD_CQR_FAILED;
1081                                 cqr->stopclk = get_clock();
1082                         } else {
1083                                 if (cqr->irb.esw.esw0.erw.cons) {
1084                                         erp_fn = device->discipline->
1085                                                 erp_action(cqr);
1086                                         erp_fn(cqr);
1087                                 } else
1088                                         dasd_default_erp_action(cqr);
1089                         }
1090                         goto restart;
1091                 }
1092                 /* Process finished ERP request. */
1093                 if (cqr->refers) {
1094                         __dasd_process_erp(device, cqr);
1095                         goto restart;
1096                 }
1097
1098                 /* Rechain finished requests to final queue */
1099                 cqr->endclk = get_clock();
1100                 list_move_tail(&cqr->list, final_queue);
1101         }
1102 }
1103
1104 static void
1105 dasd_end_request_cb(struct dasd_ccw_req * cqr, void *data)
1106 {
1107         struct request *req;
1108         struct dasd_device *device;
1109         int status;
1110
1111         req = (struct request *) data;
1112         device = cqr->device;
1113         dasd_profile_end(device, cqr, req);
1114         status = cqr->device->discipline->free_cp(cqr,req);
1115         spin_lock_irq(&device->request_queue_lock);
1116         dasd_end_request(req, status);
1117         spin_unlock_irq(&device->request_queue_lock);
1118 }
1119
1120
1121 /*
1122  * Fetch requests from the block device queue.
1123  */
1124 static inline void
1125 __dasd_process_blk_queue(struct dasd_device * device)
1126 {
1127         request_queue_t *queue;
1128         struct request *req;
1129         struct dasd_ccw_req *cqr;
1130         int nr_queued;
1131
1132         queue = device->request_queue;
1133         /* No queue ? Then there is nothing to do. */
1134         if (queue == NULL)
1135                 return;
1136
1137         /*
1138          * We requeue request from the block device queue to the ccw
1139          * queue only in two states. In state DASD_STATE_READY the
1140          * partition detection is done and we need to requeue requests
1141          * for that. State DASD_STATE_ONLINE is normal block device
1142          * operation.
1143          */
1144         if (device->state != DASD_STATE_READY &&
1145             device->state != DASD_STATE_ONLINE)
1146                 return;
1147         nr_queued = 0;
1148         /* Now we try to fetch requests from the request queue */
1149         list_for_each_entry(cqr, &device->ccw_queue, list)
1150                 if (cqr->status == DASD_CQR_QUEUED)
1151                         nr_queued++;
1152         while (!blk_queue_plugged(queue) &&
1153                elv_next_request(queue) &&
1154                 nr_queued < DASD_CHANQ_MAX_SIZE) {
1155                 req = elv_next_request(queue);
1156
1157                 if (device->features & DASD_FEATURE_READONLY &&
1158                     rq_data_dir(req) == WRITE) {
1159                         DBF_DEV_EVENT(DBF_ERR, device,
1160                                       "Rejecting write request %p",
1161                                       req);
1162                         blkdev_dequeue_request(req);
1163                         dasd_end_request(req, 0);
1164                         continue;
1165                 }
1166                 if (device->stopped & DASD_STOPPED_DC_EIO) {
1167                         blkdev_dequeue_request(req);
1168                         dasd_end_request(req, 0);
1169                         continue;
1170                 }
1171                 cqr = device->discipline->build_cp(device, req);
1172                 if (IS_ERR(cqr)) {
1173                         if (PTR_ERR(cqr) == -ENOMEM)
1174                                 break;  /* terminate request queue loop */
1175                         DBF_DEV_EVENT(DBF_ERR, device,
1176                                       "CCW creation failed (rc=%ld) "
1177                                       "on request %p",
1178                                       PTR_ERR(cqr), req);
1179                         blkdev_dequeue_request(req);
1180                         dasd_end_request(req, 0);
1181                         continue;
1182                 }
1183                 cqr->callback = dasd_end_request_cb;
1184                 cqr->callback_data = (void *) req;
1185                 cqr->status = DASD_CQR_QUEUED;
1186                 blkdev_dequeue_request(req);
1187                 list_add_tail(&cqr->list, &device->ccw_queue);
1188                 dasd_profile_start(device, cqr, req);
1189                 nr_queued++;
1190         }
1191 }
1192
1193 /*
1194  * Take a look at the first request on the ccw queue and check
1195  * if it reached its expire time. If so, terminate the IO.
1196  */
1197 static inline void
1198 __dasd_check_expire(struct dasd_device * device)
1199 {
1200         struct dasd_ccw_req *cqr;
1201
1202         if (list_empty(&device->ccw_queue))
1203                 return;
1204         cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
1205         if (cqr->status == DASD_CQR_IN_IO && cqr->expires != 0) {
1206                 if (time_after_eq(jiffies, cqr->expires + cqr->starttime)) {
1207                         if (device->discipline->term_IO(cqr) != 0)
1208                                 /* Hmpf, try again in 1/10 sec */
1209                                 dasd_set_timer(device, 10);
1210                 }
1211         }
1212 }
1213
1214 /*
1215  * Take a look at the first request on the ccw queue and check
1216  * if it needs to be started.
1217  */
1218 static inline void
1219 __dasd_start_head(struct dasd_device * device)
1220 {
1221         struct dasd_ccw_req *cqr;
1222         int rc;
1223
1224         if (list_empty(&device->ccw_queue))
1225                 return;
1226         cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
1227         if ((cqr->status == DASD_CQR_QUEUED) &&
1228             (!device->stopped)) {
1229                 /* try to start the first I/O that can be started */
1230                 rc = device->discipline->start_IO(cqr);
1231                 if (rc == 0)
1232                         dasd_set_timer(device, cqr->expires);
1233                 else if (rc == -EACCES) {
1234                         dasd_schedule_bh(device);
1235                 } else
1236                         /* Hmpf, try again in 1/2 sec */
1237                         dasd_set_timer(device, 50);
1238         }
1239 }
1240
1241 /*
1242  * Remove requests from the ccw queue. 
1243  */
1244 static void
1245 dasd_flush_ccw_queue(struct dasd_device * device, int all)
1246 {
1247         struct list_head flush_queue;
1248         struct list_head *l, *n;
1249         struct dasd_ccw_req *cqr;
1250
1251         INIT_LIST_HEAD(&flush_queue);
1252         spin_lock_irq(get_ccwdev_lock(device->cdev));
1253         list_for_each_safe(l, n, &device->ccw_queue) {
1254                 cqr = list_entry(l, struct dasd_ccw_req, list);
1255                 /* Flush all request or only block device requests? */
1256                 if (all == 0 && cqr->callback == dasd_end_request_cb)
1257                         continue;
1258                 if (cqr->status == DASD_CQR_IN_IO)
1259                         device->discipline->term_IO(cqr);
1260                 if (cqr->status != DASD_CQR_DONE ||
1261                     cqr->status != DASD_CQR_FAILED) {
1262                         cqr->status = DASD_CQR_FAILED;
1263                         cqr->stopclk = get_clock();
1264                 }
1265                 /* Process finished ERP request. */
1266                 if (cqr->refers) {
1267                         __dasd_process_erp(device, cqr);
1268                         continue;
1269                 }
1270                 /* Rechain request on device request queue */
1271                 cqr->endclk = get_clock();
1272                 list_move_tail(&cqr->list, &flush_queue);
1273         }
1274         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1275         /* Now call the callback function of flushed requests */
1276         list_for_each_safe(l, n, &flush_queue) {
1277                 cqr = list_entry(l, struct dasd_ccw_req, list);
1278                 if (cqr->callback != NULL)
1279                         (cqr->callback)(cqr, cqr->callback_data);
1280         }
1281 }
1282
1283 /*
1284  * Acquire the device lock and process queues for the device.
1285  */
1286 static void
1287 dasd_tasklet(struct dasd_device * device)
1288 {
1289         struct list_head final_queue;
1290         struct list_head *l, *n;
1291         struct dasd_ccw_req *cqr;
1292
1293         atomic_set (&device->tasklet_scheduled, 0);
1294         INIT_LIST_HEAD(&final_queue);
1295         spin_lock_irq(get_ccwdev_lock(device->cdev));
1296         /* Check expire time of first request on the ccw queue. */
1297         __dasd_check_expire(device);
1298         /* Finish off requests on ccw queue */
1299         __dasd_process_ccw_queue(device, &final_queue);
1300         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1301         /* Now call the callback function of requests with final status */
1302         list_for_each_safe(l, n, &final_queue) {
1303                 cqr = list_entry(l, struct dasd_ccw_req, list);
1304                 list_del(&cqr->list);
1305                 if (cqr->callback != NULL)
1306                         (cqr->callback)(cqr, cqr->callback_data);
1307         }
1308         spin_lock_irq(&device->request_queue_lock);
1309         spin_lock(get_ccwdev_lock(device->cdev));
1310         /* Get new request from the block device request queue */
1311         __dasd_process_blk_queue(device);
1312         /* Now check if the head of the ccw queue needs to be started. */
1313         __dasd_start_head(device);
1314         spin_unlock(get_ccwdev_lock(device->cdev));
1315         spin_unlock_irq(&device->request_queue_lock);
1316         dasd_put_device(device);
1317 }
1318
1319 /*
1320  * Schedules a call to dasd_tasklet over the device tasklet.
1321  */
1322 void
1323 dasd_schedule_bh(struct dasd_device * device)
1324 {
1325         /* Protect against rescheduling. */
1326         if (atomic_compare_and_swap (0, 1, &device->tasklet_scheduled))
1327                 return;
1328         dasd_get_device(device);
1329         tasklet_hi_schedule(&device->tasklet);
1330 }
1331
1332 /*
1333  * Queue a request to the head of the ccw_queue. Start the I/O if
1334  * possible.
1335  */
1336 void
1337 dasd_add_request_head(struct dasd_ccw_req *req)
1338 {
1339         struct dasd_device *device;
1340         unsigned long flags;
1341
1342         device = req->device;
1343         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
1344         req->status = DASD_CQR_QUEUED;
1345         req->device = device;
1346         list_add(&req->list, &device->ccw_queue);
1347         /* let the bh start the request to keep them in order */
1348         dasd_schedule_bh(device);
1349         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
1350 }
1351
1352 /*
1353  * Queue a request to the tail of the ccw_queue. Start the I/O if
1354  * possible.
1355  */
1356 void
1357 dasd_add_request_tail(struct dasd_ccw_req *req)
1358 {
1359         struct dasd_device *device;
1360         unsigned long flags;
1361
1362         device = req->device;
1363         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
1364         req->status = DASD_CQR_QUEUED;
1365         req->device = device;
1366         list_add_tail(&req->list, &device->ccw_queue);
1367         /* let the bh start the request to keep them in order */
1368         dasd_schedule_bh(device);
1369         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
1370 }
1371
1372 /*
1373  * Wakeup callback.
1374  */
1375 static void
1376 dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
1377 {
1378         wake_up((wait_queue_head_t *) data);
1379 }
1380
1381 static inline int
1382 _wait_for_wakeup(struct dasd_ccw_req *cqr)
1383 {
1384         struct dasd_device *device;
1385         int rc;
1386
1387         device = cqr->device;
1388         spin_lock_irq(get_ccwdev_lock(device->cdev));
1389         rc = cqr->status == DASD_CQR_DONE || cqr->status == DASD_CQR_FAILED;
1390         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1391         return rc;
1392 }
1393
1394 /*
1395  * Attempts to start a special ccw queue and waits for its completion.
1396  */
1397 int
1398 dasd_sleep_on(struct dasd_ccw_req * cqr)
1399 {
1400         wait_queue_head_t wait_q;
1401         struct dasd_device *device;
1402         int rc;
1403         
1404         device = cqr->device;
1405         spin_lock_irq(get_ccwdev_lock(device->cdev));
1406         
1407         init_waitqueue_head (&wait_q);
1408         cqr->callback = dasd_wakeup_cb;
1409         cqr->callback_data = (void *) &wait_q;
1410         cqr->status = DASD_CQR_QUEUED;
1411         list_add_tail(&cqr->list, &device->ccw_queue);
1412         
1413         /* let the bh start the request to keep them in order */
1414         dasd_schedule_bh(device);
1415         
1416         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1417
1418         wait_event(wait_q, _wait_for_wakeup(cqr));
1419         
1420         /* Request status is either done or failed. */
1421         rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
1422         return rc;
1423 }
1424
1425 /*
1426  * Attempts to start a special ccw queue and wait interruptible
1427  * for its completion.
1428  */
1429 int
1430 dasd_sleep_on_interruptible(struct dasd_ccw_req * cqr)
1431 {
1432         wait_queue_head_t wait_q;
1433         struct dasd_device *device;
1434         int rc, finished;
1435
1436         device = cqr->device;
1437         spin_lock_irq(get_ccwdev_lock(device->cdev));
1438
1439         init_waitqueue_head (&wait_q);
1440         cqr->callback = dasd_wakeup_cb;
1441         cqr->callback_data = (void *) &wait_q;
1442         cqr->status = DASD_CQR_QUEUED;
1443         list_add_tail(&cqr->list, &device->ccw_queue);
1444
1445         /* let the bh start the request to keep them in order */
1446         dasd_schedule_bh(device);
1447         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1448
1449         finished = 0;
1450         while (!finished) {
1451                 rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr));
1452                 if (rc != -ERESTARTSYS) {
1453                         /* Request status is either done or failed. */
1454                         rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
1455                         break;
1456                 }
1457                 spin_lock_irq(get_ccwdev_lock(device->cdev));
1458                 if (cqr->status == DASD_CQR_IN_IO &&
1459                     device->discipline->term_IO(cqr) == 0) {
1460                         list_del(&cqr->list);
1461                         finished = 1;
1462                 }
1463                 spin_unlock_irq(get_ccwdev_lock(device->cdev));
1464         }
1465         return rc;
1466 }
1467
1468 /*
1469  * Whoa nelly now it gets really hairy. For some functions (e.g. steal lock
1470  * for eckd devices) the currently running request has to be terminated
1471  * and be put back to status queued, before the special request is added
1472  * to the head of the queue. Then the special request is waited on normally.
1473  */
1474 static inline int
1475 _dasd_term_running_cqr(struct dasd_device *device)
1476 {
1477         struct dasd_ccw_req *cqr;
1478         int rc;
1479
1480         if (list_empty(&device->ccw_queue))
1481                 return 0;
1482         cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
1483         rc = device->discipline->term_IO(cqr);
1484         if (rc == 0) {
1485                 /* termination successful */
1486                 cqr->status = DASD_CQR_QUEUED;
1487                 cqr->startclk = cqr->stopclk = 0;
1488                 cqr->starttime = 0;
1489         }
1490         return rc;
1491 }
1492
1493 int
1494 dasd_sleep_on_immediatly(struct dasd_ccw_req * cqr)
1495 {
1496         wait_queue_head_t wait_q;
1497         struct dasd_device *device;
1498         int rc;
1499         
1500         device = cqr->device;
1501         spin_lock_irq(get_ccwdev_lock(device->cdev));
1502         rc = _dasd_term_running_cqr(device);
1503         if (rc) {
1504                 spin_unlock_irq(get_ccwdev_lock(device->cdev));
1505                 return rc;
1506         }
1507         
1508         init_waitqueue_head (&wait_q);
1509         cqr->callback = dasd_wakeup_cb;
1510         cqr->callback_data = (void *) &wait_q;
1511         cqr->status = DASD_CQR_QUEUED;
1512         list_add(&cqr->list, &device->ccw_queue);
1513         
1514         /* let the bh start the request to keep them in order */
1515         dasd_schedule_bh(device);
1516         
1517         spin_unlock_irq(get_ccwdev_lock(device->cdev));
1518
1519         wait_event(wait_q, _wait_for_wakeup(cqr));
1520         
1521         /* Request status is either done or failed. */
1522         rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
1523         return rc;
1524 }
1525
1526 /*
1527  * Cancels a request that was started with dasd_sleep_on_req.
1528  * This is useful to timeout requests. The request will be
1529  * terminated if it is currently in i/o.
1530  * Returns 1 if the request has been terminated.
1531  */
1532 int
1533 dasd_cancel_req(struct dasd_ccw_req *cqr)
1534 {
1535         struct dasd_device *device = cqr->device;
1536         unsigned long flags;
1537         int rc;
1538
1539         rc = 0;
1540         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
1541         switch (cqr->status) {
1542         case DASD_CQR_QUEUED:
1543                 /* request was not started - just set to failed */
1544                 cqr->status = DASD_CQR_FAILED;
1545                 break;
1546         case DASD_CQR_IN_IO:
1547                 /* request in IO - terminate IO and release again */
1548                 if (device->discipline->term_IO(cqr) != 0)
1549                         /* what to do if unable to terminate ??????
1550                            e.g. not _IN_IO */
1551                         cqr->status = DASD_CQR_FAILED;
1552                 cqr->stopclk = get_clock();
1553                 rc = 1;
1554                 break;
1555         case DASD_CQR_DONE:
1556         case DASD_CQR_FAILED:
1557                 /* already finished - do nothing */
1558                 break;
1559         default:
1560                 DEV_MESSAGE(KERN_ALERT, device,
1561                             "invalid status %02x in request",
1562                             cqr->status);
1563                 BUG();
1564
1565         }
1566         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
1567         dasd_schedule_bh(device);
1568         return rc;
1569 }
1570
1571 /*
1572  * SECTION: Block device operations (request queue, partitions, open, release).
1573  */
1574
1575 /*
1576  * Dasd request queue function. Called from ll_rw_blk.c
1577  */
1578 static void
1579 do_dasd_request(request_queue_t * queue)
1580 {
1581         struct dasd_device *device;
1582
1583         device = (struct dasd_device *) queue->queuedata;
1584         spin_lock(get_ccwdev_lock(device->cdev));
1585         /* Get new request from the block device request queue */
1586         __dasd_process_blk_queue(device);
1587         /* Now check if the head of the ccw queue needs to be started. */
1588         __dasd_start_head(device);
1589         spin_unlock(get_ccwdev_lock(device->cdev));
1590 }
1591
1592 /*
1593  * Allocate and initialize request queue and default I/O scheduler.
1594  */
1595 static int
1596 dasd_alloc_queue(struct dasd_device * device)
1597 {
1598         int rc;
1599
1600         device->request_queue = blk_init_queue(do_dasd_request,
1601                                                &device->request_queue_lock);
1602         if (device->request_queue == NULL)
1603                 return -ENOMEM;
1604
1605         device->request_queue->queuedata = device;
1606
1607         elevator_exit(device->request_queue->elevator);
1608         rc = elevator_init(device->request_queue, "deadline");
1609         if (rc) {
1610                 blk_cleanup_queue(device->request_queue);
1611                 return rc;
1612         }
1613         return 0;
1614 }
1615
1616 /*
1617  * Allocate and initialize request queue.
1618  */
1619 static void
1620 dasd_setup_queue(struct dasd_device * device)
1621 {
1622         int max;
1623
1624         blk_queue_hardsect_size(device->request_queue, device->bp_block);
1625         max = device->discipline->max_blocks << device->s2b_shift;
1626         blk_queue_max_sectors(device->request_queue, max);
1627         blk_queue_max_phys_segments(device->request_queue, -1L);
1628         blk_queue_max_hw_segments(device->request_queue, -1L);
1629         blk_queue_max_segment_size(device->request_queue, -1L);
1630         blk_queue_segment_boundary(device->request_queue, -1L);
1631         blk_queue_ordered(device->request_queue, 1);
1632 }
1633
1634 /*
1635  * Deactivate and free request queue.
1636  */
1637 static void
1638 dasd_free_queue(struct dasd_device * device)
1639 {
1640         if (device->request_queue) {
1641                 blk_cleanup_queue(device->request_queue);
1642                 device->request_queue = NULL;
1643         }
1644 }
1645
1646 /*
1647  * Flush request on the request queue.
1648  */
1649 static void
1650 dasd_flush_request_queue(struct dasd_device * device)
1651 {
1652         struct request *req;
1653
1654         if (!device->request_queue)
1655                 return;
1656         
1657         spin_lock_irq(&device->request_queue_lock);
1658         while (!list_empty(&device->request_queue->queue_head)) {
1659                 req = elv_next_request(device->request_queue);
1660                 if (req == NULL)
1661                         break;
1662                 dasd_end_request(req, 0);
1663                 blkdev_dequeue_request(req);
1664         }
1665         spin_unlock_irq(&device->request_queue_lock);
1666 }
1667
1668 static int
1669 dasd_open(struct inode *inp, struct file *filp)
1670 {
1671         struct gendisk *disk = inp->i_bdev->bd_disk;
1672         struct dasd_device *device = disk->private_data;
1673         int rc;
1674
1675         atomic_inc(&device->open_count);
1676         if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
1677                 rc = -ENODEV;
1678                 goto unlock;
1679         }
1680
1681         if (!try_module_get(device->discipline->owner)) {
1682                 rc = -EINVAL;
1683                 goto unlock;
1684         }
1685
1686         if (dasd_probeonly) {
1687                 DEV_MESSAGE(KERN_INFO, device, "%s",
1688                             "No access to device due to probeonly mode");
1689                 rc = -EPERM;
1690                 goto out;
1691         }
1692
1693         if (device->state < DASD_STATE_BASIC) {
1694                 DBF_DEV_EVENT(DBF_ERR, device, " %s",
1695                               " Cannot open unrecognized device");
1696                 rc = -ENODEV;
1697                 goto out;
1698         }
1699
1700         return 0;
1701
1702 out:
1703         module_put(device->discipline->owner);
1704 unlock:
1705         atomic_dec(&device->open_count);
1706         return rc;
1707 }
1708
1709 static int
1710 dasd_release(struct inode *inp, struct file *filp)
1711 {
1712         struct gendisk *disk = inp->i_bdev->bd_disk;
1713         struct dasd_device *device = disk->private_data;
1714
1715         atomic_dec(&device->open_count);
1716         module_put(device->discipline->owner);
1717         return 0;
1718 }
1719
1720 struct block_device_operations
1721 dasd_device_operations = {
1722         .owner          = THIS_MODULE,
1723         .open           = dasd_open,
1724         .release        = dasd_release,
1725         .ioctl          = dasd_ioctl,
1726 };
1727
1728
1729 static void
1730 dasd_exit(void)
1731 {
1732 #ifdef CONFIG_PROC_FS
1733         dasd_proc_exit();
1734 #endif
1735         dasd_ioctl_exit();
1736         if (dasd_page_cache != NULL) {
1737                 kmem_cache_destroy(dasd_page_cache);
1738                 dasd_page_cache = NULL;
1739         }
1740         dasd_gendisk_exit();
1741         dasd_devmap_exit();
1742         devfs_remove("dasd");
1743         if (dasd_debug_area != NULL) {
1744                 debug_unregister(dasd_debug_area);
1745                 dasd_debug_area = NULL;
1746         }
1747 }
1748
1749 /*
1750  * SECTION: common functions for ccw_driver use
1751  */
1752
1753 /* initial attempt at a probe function. this can be simplified once
1754  * the other detection code is gone */
1755 int
1756 dasd_generic_probe (struct ccw_device *cdev,
1757                     struct dasd_discipline *discipline)
1758 {
1759         int ret;
1760
1761         ret = dasd_add_sysfs_files(cdev);
1762         if (ret) {
1763                 printk(KERN_WARNING
1764                        "dasd_generic_probe: could not add sysfs entries "
1765                        "for %s\n", cdev->dev.bus_id);
1766         } else {
1767                 cdev->handler = &dasd_int_handler;
1768         }
1769
1770         return ret;
1771 }
1772
1773 /* this will one day be called from a global not_oper handler.
1774  * It is also used by driver_unregister during module unload */
1775 void
1776 dasd_generic_remove (struct ccw_device *cdev)
1777 {
1778         struct dasd_device *device;
1779
1780         cdev->handler = NULL;
1781
1782         dasd_remove_sysfs_files(cdev);
1783         device = dasd_device_from_cdev(cdev);
1784         if (IS_ERR(device))
1785                 return;
1786         if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
1787                 /* Already doing offline processing */
1788                 dasd_put_device(device);
1789                 return;
1790         }
1791         /*
1792          * This device is removed unconditionally. Set offline
1793          * flag to prevent dasd_open from opening it while it is
1794          * no quite down yet.
1795          */
1796         dasd_set_target_state(device, DASD_STATE_NEW);
1797         /* dasd_delete_device destroys the device reference. */
1798         dasd_delete_device(device);
1799 }
1800
1801 /* activate a device. This is called from dasd_{eckd,fba}_probe() when either
1802  * the device is detected for the first time and is supposed to be used
1803  * or the user has started activation through sysfs */
1804 int
1805 dasd_generic_set_online (struct ccw_device *cdev,
1806                          struct dasd_discipline *discipline)
1807
1808 {
1809         struct dasd_device *device;
1810         int rc;
1811
1812         device = dasd_create_device(cdev);
1813         if (IS_ERR(device))
1814                 return PTR_ERR(device);
1815
1816         if (device->features & DASD_FEATURE_USEDIAG) {
1817                 if (!dasd_diag_discipline_pointer) {
1818                         printk (KERN_WARNING
1819                                 "dasd_generic couldn't online device %s "
1820                                 "- discipline DIAG not available\n",
1821                                 cdev->dev.bus_id);
1822                         dasd_delete_device(device);
1823                         return -ENODEV;
1824                 }
1825                 discipline = dasd_diag_discipline_pointer;
1826         }
1827         device->discipline = discipline;
1828
1829         rc = discipline->check_device(device);
1830         if (rc) {
1831                 printk (KERN_WARNING
1832                         "dasd_generic couldn't online device %s "
1833                         "with discipline %s rc=%i\n",
1834                         cdev->dev.bus_id, discipline->name, rc);
1835                 dasd_delete_device(device);
1836                 return rc;
1837         }
1838
1839         dasd_set_target_state(device, DASD_STATE_ONLINE);
1840         if (device->state <= DASD_STATE_KNOWN) {
1841                 printk (KERN_WARNING
1842                         "dasd_generic discipline not found for %s\n",
1843                         cdev->dev.bus_id);
1844                 rc = -ENODEV;
1845                 dasd_set_target_state(device, DASD_STATE_NEW);
1846                 dasd_delete_device(device);
1847         } else
1848                 pr_debug("dasd_generic device %s found\n",
1849                                 cdev->dev.bus_id);
1850
1851         /* FIXME: we have to wait for the root device but we don't want
1852          * to wait for each single device but for all at once. */
1853         wait_event(dasd_init_waitq, _wait_for_device(device));
1854
1855         dasd_put_device(device);
1856
1857         return rc;
1858 }
1859
1860 int
1861 dasd_generic_set_offline (struct ccw_device *cdev)
1862 {
1863         struct dasd_device *device;
1864         int max_count;
1865
1866         device = dasd_device_from_cdev(cdev);
1867         if (IS_ERR(device))
1868                 return PTR_ERR(device);
1869         if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
1870                 /* Already doing offline processing */
1871                 dasd_put_device(device);
1872                 return 0;
1873         }
1874         /*
1875          * We must make sure that this device is currently not in use.
1876          * The open_count is increased for every opener, that includes
1877          * the blkdev_get in dasd_scan_partitions. We are only interested
1878          * in the other openers.
1879          */
1880         max_count = device->bdev ? 0 : -1;
1881         if (atomic_read(&device->open_count) > max_count) {
1882                 printk (KERN_WARNING "Can't offline dasd device with open"
1883                         " count = %i.\n",
1884                         atomic_read(&device->open_count));
1885                 clear_bit(DASD_FLAG_OFFLINE, &device->flags);
1886                 dasd_put_device(device);
1887                 return -EBUSY;
1888         }
1889         dasd_set_target_state(device, DASD_STATE_NEW);
1890         /* dasd_delete_device destroys the device reference. */
1891         dasd_delete_device(device);
1892
1893         return 0;
1894 }
1895
1896 int
1897 dasd_generic_notify(struct ccw_device *cdev, int event)
1898 {
1899         struct dasd_device *device;
1900         struct dasd_ccw_req *cqr;
1901         unsigned long flags;
1902         int ret;
1903
1904         device = dasd_device_from_cdev(cdev);
1905         if (IS_ERR(device))
1906                 return 0;
1907         spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
1908         ret = 0;
1909         switch (event) {
1910         case CIO_GONE:
1911         case CIO_NO_PATH:
1912                 if (device->state < DASD_STATE_BASIC)
1913                         break;
1914                 /* Device is active. We want to keep it. */
1915                 if (test_bit(DASD_FLAG_DSC_ERROR, &device->flags)) {
1916                         list_for_each_entry(cqr, &device->ccw_queue, list)
1917                                 if (cqr->status == DASD_CQR_IN_IO)
1918                                         cqr->status = DASD_CQR_FAILED;
1919                         device->stopped |= DASD_STOPPED_DC_EIO;
1920                         dasd_schedule_bh(device);
1921                 } else {
1922                         list_for_each_entry(cqr, &device->ccw_queue, list)
1923                                 if (cqr->status == DASD_CQR_IN_IO) {
1924                                         cqr->status = DASD_CQR_QUEUED;
1925                                         cqr->retries++;
1926                                 }
1927                         device->stopped |= DASD_STOPPED_DC_WAIT;
1928                         dasd_set_timer(device, 0);
1929                 }
1930                 ret = 1;
1931                 break;
1932         case CIO_OPER:
1933                 /* FIXME: add a sanity check. */
1934                 device->stopped &= ~(DASD_STOPPED_DC_WAIT|DASD_STOPPED_DC_EIO);
1935                 dasd_schedule_bh(device);
1936                 ret = 1;
1937                 break;
1938         }
1939         spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
1940         dasd_put_device(device);
1941         return ret;
1942 }
1943
1944 /*
1945  * Automatically online either all dasd devices (dasd_autodetect) or
1946  * all devices specified with dasd= parameters.
1947  */
1948 static int
1949 __dasd_auto_online(struct device *dev, void *data)
1950 {
1951         struct ccw_device *cdev;
1952
1953         cdev = to_ccwdev(dev);
1954         if (dasd_autodetect || dasd_busid_known(cdev->dev.bus_id) == 0)
1955                 ccw_device_set_online(cdev);
1956         return 0;
1957 }
1958
1959 void
1960 dasd_generic_auto_online (struct ccw_driver *dasd_discipline_driver)
1961 {
1962         struct device_driver *drv;
1963
1964         drv = get_driver(&dasd_discipline_driver->driver);
1965         driver_for_each_device(drv, NULL, NULL, __dasd_auto_online);
1966         put_driver(drv);
1967 }
1968
1969 static int __init
1970 dasd_init(void)
1971 {
1972         int rc;
1973
1974         init_waitqueue_head(&dasd_init_waitq);
1975
1976         /* register 'common' DASD debug area, used for all DBF_XXX calls */
1977         dasd_debug_area = debug_register("dasd", 1, 2, 8 * sizeof (long));
1978         if (dasd_debug_area == NULL) {
1979                 rc = -ENOMEM;
1980                 goto failed;
1981         }
1982         debug_register_view(dasd_debug_area, &debug_sprintf_view);
1983         debug_set_level(dasd_debug_area, DBF_EMERG);
1984
1985         DBF_EVENT(DBF_EMERG, "%s", "debug area created");
1986
1987         dasd_diag_discipline_pointer = NULL;
1988
1989         rc = devfs_mk_dir("dasd");
1990         if (rc)
1991                 goto failed;
1992         rc = dasd_devmap_init();
1993         if (rc)
1994                 goto failed;
1995         rc = dasd_gendisk_init();
1996         if (rc)
1997                 goto failed;
1998         rc = dasd_parse();
1999         if (rc)
2000                 goto failed;
2001         rc = dasd_ioctl_init();
2002         if (rc)
2003                 goto failed;
2004 #ifdef CONFIG_PROC_FS
2005         rc = dasd_proc_init();
2006         if (rc)
2007                 goto failed;
2008 #endif
2009
2010         return 0;
2011 failed:
2012         MESSAGE(KERN_INFO, "%s", "initialization not performed due to errors");
2013         dasd_exit();
2014         return rc;
2015 }
2016
2017 module_init(dasd_init);
2018 module_exit(dasd_exit);
2019
2020 EXPORT_SYMBOL(dasd_debug_area);
2021 EXPORT_SYMBOL(dasd_diag_discipline_pointer);
2022
2023 EXPORT_SYMBOL(dasd_add_request_head);
2024 EXPORT_SYMBOL(dasd_add_request_tail);
2025 EXPORT_SYMBOL(dasd_cancel_req);
2026 EXPORT_SYMBOL(dasd_clear_timer);
2027 EXPORT_SYMBOL(dasd_enable_device);
2028 EXPORT_SYMBOL(dasd_int_handler);
2029 EXPORT_SYMBOL(dasd_kfree_request);
2030 EXPORT_SYMBOL(dasd_kick_device);
2031 EXPORT_SYMBOL(dasd_kmalloc_request);
2032 EXPORT_SYMBOL(dasd_schedule_bh);
2033 EXPORT_SYMBOL(dasd_set_target_state);
2034 EXPORT_SYMBOL(dasd_set_timer);
2035 EXPORT_SYMBOL(dasd_sfree_request);
2036 EXPORT_SYMBOL(dasd_sleep_on);
2037 EXPORT_SYMBOL(dasd_sleep_on_immediatly);
2038 EXPORT_SYMBOL(dasd_sleep_on_interruptible);
2039 EXPORT_SYMBOL(dasd_smalloc_request);
2040 EXPORT_SYMBOL(dasd_start_IO);
2041 EXPORT_SYMBOL(dasd_term_IO);
2042
2043 EXPORT_SYMBOL_GPL(dasd_generic_probe);
2044 EXPORT_SYMBOL_GPL(dasd_generic_remove);
2045 EXPORT_SYMBOL_GPL(dasd_generic_notify);
2046 EXPORT_SYMBOL_GPL(dasd_generic_set_online);
2047 EXPORT_SYMBOL_GPL(dasd_generic_set_offline);
2048 EXPORT_SYMBOL_GPL(dasd_generic_auto_online);
2049
2050 /*
2051  * Overrides for Emacs so that we follow Linus's tabbing style.
2052  * Emacs will notice this stuff at the end of the file and automatically
2053  * adjust the settings for this buffer only.  This must remain at the end
2054  * of the file.
2055  * ---------------------------------------------------------------------------
2056  * Local variables:
2057  * c-indent-level: 4
2058  * c-brace-imaginary-offset: 0
2059  * c-brace-offset: -4
2060  * c-argdecl-indent: 4
2061  * c-label-offset: -4
2062  * c-continued-statement-offset: 4
2063  * c-continued-brace-offset: 0
2064  * indent-tabs-mode: 1
2065  * tab-width: 8
2066  * End:
2067  */