[SCSI] fix potential panic with proc on module removal
[linux-2.6.git] / drivers / scsi / hosts.c
1 /*
2  *  hosts.c Copyright (C) 1992 Drew Eckhardt
3  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
4  *          Copyright (C) 2002-2003 Christoph Hellwig
5  *
6  *  mid to lowlevel SCSI driver interface
7  *      Initial versions: Drew Eckhardt
8  *      Subsequent revisions: Eric Youngdale
9  *
10  *  <drew@colorado.edu>
11  *
12  *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
13  *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
14  *     August 4, 1999 Fred Lewis, Intel DuPont
15  *
16  *  Updated to reflect the new initialization scheme for the higher 
17  *  level of scsi drivers (sd/sr/st)
18  *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
19  *
20  *  Restructured scsi_host lists and associated functions.
21  *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
22  */
23
24 #include <linux/module.h>
25 #include <linux/blkdev.h>
26 #include <linux/kernel.h>
27 #include <linux/kthread.h>
28 #include <linux/string.h>
29 #include <linux/mm.h>
30 #include <linux/init.h>
31 #include <linux/completion.h>
32 #include <linux/transport_class.h>
33
34 #include <scsi/scsi_device.h>
35 #include <scsi/scsi_host.h>
36 #include <scsi/scsi_transport.h>
37
38 #include "scsi_priv.h"
39 #include "scsi_logging.h"
40
41
42 static int scsi_host_next_hn;           /* host_no for next new host */
43
44
45 static void scsi_host_cls_release(struct class_device *class_dev)
46 {
47         put_device(&class_to_shost(class_dev)->shost_gendev);
48 }
49
50 static struct class shost_class = {
51         .name           = "scsi_host",
52         .release        = scsi_host_cls_release,
53 };
54
55 /**
56  *      scsi_host_set_state - Take the given host through the host
57  *              state model.
58  *      @shost: scsi host to change the state of.
59  *      @state: state to change to.
60  *
61  *      Returns zero if unsuccessful or an error if the requested
62  *      transition is illegal.
63  **/
64 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
65 {
66         enum scsi_host_state oldstate = shost->shost_state;
67
68         if (state == oldstate)
69                 return 0;
70
71         switch (state) {
72         case SHOST_CREATED:
73                 /* There are no legal states that come back to
74                  * created.  This is the manually initialised start
75                  * state */
76                 goto illegal;
77
78         case SHOST_RUNNING:
79                 switch (oldstate) {
80                 case SHOST_CREATED:
81                 case SHOST_RECOVERY:
82                         break;
83                 default:
84                         goto illegal;
85                 }
86                 break;
87
88         case SHOST_RECOVERY:
89                 switch (oldstate) {
90                 case SHOST_RUNNING:
91                         break;
92                 default:
93                         goto illegal;
94                 }
95                 break;
96
97         case SHOST_CANCEL:
98                 switch (oldstate) {
99                 case SHOST_CREATED:
100                 case SHOST_RUNNING:
101                 case SHOST_CANCEL_RECOVERY:
102                         break;
103                 default:
104                         goto illegal;
105                 }
106                 break;
107
108         case SHOST_DEL:
109                 switch (oldstate) {
110                 case SHOST_CANCEL:
111                 case SHOST_DEL_RECOVERY:
112                         break;
113                 default:
114                         goto illegal;
115                 }
116                 break;
117
118         case SHOST_CANCEL_RECOVERY:
119                 switch (oldstate) {
120                 case SHOST_CANCEL:
121                 case SHOST_RECOVERY:
122                         break;
123                 default:
124                         goto illegal;
125                 }
126                 break;
127
128         case SHOST_DEL_RECOVERY:
129                 switch (oldstate) {
130                 case SHOST_CANCEL_RECOVERY:
131                         break;
132                 default:
133                         goto illegal;
134                 }
135                 break;
136         }
137         shost->shost_state = state;
138         return 0;
139
140  illegal:
141         SCSI_LOG_ERROR_RECOVERY(1,
142                                 dev_printk(KERN_ERR, &shost->shost_gendev,
143                                            "Illegal host state transition"
144                                            "%s->%s\n",
145                                            scsi_host_state_name(oldstate),
146                                            scsi_host_state_name(state)));
147         return -EINVAL;
148 }
149 EXPORT_SYMBOL(scsi_host_set_state);
150
151 /**
152  * scsi_remove_host - remove a scsi host
153  * @shost:      a pointer to a scsi host to remove
154  **/
155 void scsi_remove_host(struct Scsi_Host *shost)
156 {
157         unsigned long flags;
158         down(&shost->scan_mutex);
159         spin_lock_irqsave(shost->host_lock, flags);
160         if (scsi_host_set_state(shost, SHOST_CANCEL))
161                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
162                         spin_unlock_irqrestore(shost->host_lock, flags);
163                         up(&shost->scan_mutex);
164                         return;
165                 }
166         spin_unlock_irqrestore(shost->host_lock, flags);
167         up(&shost->scan_mutex);
168         scsi_forget_host(shost);
169         scsi_proc_host_rm(shost);
170
171         spin_lock_irqsave(shost->host_lock, flags);
172         if (scsi_host_set_state(shost, SHOST_DEL))
173                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
174         spin_unlock_irqrestore(shost->host_lock, flags);
175
176         transport_unregister_device(&shost->shost_gendev);
177         class_device_unregister(&shost->shost_classdev);
178         device_del(&shost->shost_gendev);
179         scsi_proc_hostdir_rm(shost->hostt);
180 }
181 EXPORT_SYMBOL(scsi_remove_host);
182
183 /**
184  * scsi_add_host - add a scsi host
185  * @shost:      scsi host pointer to add
186  * @dev:        a struct device of type scsi class
187  *
188  * Return value: 
189  *      0 on success / != 0 for error
190  **/
191 int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
192 {
193         struct scsi_host_template *sht = shost->hostt;
194         int error = -EINVAL;
195
196         printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
197                         sht->info ? sht->info(shost) : sht->name);
198
199         if (!shost->can_queue) {
200                 printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
201                                 sht->name);
202                 goto out;
203         }
204
205         if (!shost->shost_gendev.parent)
206                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
207
208         error = device_add(&shost->shost_gendev);
209         if (error)
210                 goto out;
211
212         scsi_host_set_state(shost, SHOST_RUNNING);
213         get_device(shost->shost_gendev.parent);
214
215         error = class_device_add(&shost->shost_classdev);
216         if (error)
217                 goto out_del_gendev;
218
219         get_device(&shost->shost_gendev);
220
221         if (shost->transportt->host_size &&
222             (shost->shost_data = kmalloc(shost->transportt->host_size,
223                                          GFP_KERNEL)) == NULL)
224                 goto out_del_classdev;
225
226         if (shost->transportt->create_work_queue) {
227                 snprintf(shost->work_q_name, KOBJ_NAME_LEN, "scsi_wq_%d",
228                         shost->host_no);
229                 shost->work_q = create_singlethread_workqueue(
230                                         shost->work_q_name);
231                 if (!shost->work_q)
232                         goto out_free_shost_data;
233         }
234
235         error = scsi_sysfs_add_host(shost);
236         if (error)
237                 goto out_destroy_host;
238
239         scsi_proc_host_add(shost);
240         return error;
241
242  out_destroy_host:
243         if (shost->work_q)
244                 destroy_workqueue(shost->work_q);
245  out_free_shost_data:
246         kfree(shost->shost_data);
247  out_del_classdev:
248         class_device_del(&shost->shost_classdev);
249  out_del_gendev:
250         device_del(&shost->shost_gendev);
251  out:
252         return error;
253 }
254 EXPORT_SYMBOL(scsi_add_host);
255
256 static void scsi_host_dev_release(struct device *dev)
257 {
258         struct Scsi_Host *shost = dev_to_shost(dev);
259         struct device *parent = dev->parent;
260
261         if (shost->ehandler)
262                 kthread_stop(shost->ehandler);
263         if (shost->work_q)
264                 destroy_workqueue(shost->work_q);
265
266         scsi_destroy_command_freelist(shost);
267         kfree(shost->shost_data);
268
269         if (parent)
270                 put_device(parent);
271         kfree(shost);
272 }
273
274 /**
275  * scsi_host_alloc - register a scsi host adapter instance.
276  * @sht:        pointer to scsi host template
277  * @privsize:   extra bytes to allocate for driver
278  *
279  * Note:
280  *      Allocate a new Scsi_Host and perform basic initialization.
281  *      The host is not published to the scsi midlayer until scsi_add_host
282  *      is called.
283  *
284  * Return value:
285  *      Pointer to a new Scsi_Host
286  **/
287 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
288 {
289         struct Scsi_Host *shost;
290         int gfp_mask = GFP_KERNEL, rval;
291
292         if (sht->unchecked_isa_dma && privsize)
293                 gfp_mask |= __GFP_DMA;
294
295         /* Check to see if this host has any error handling facilities */
296         if (!sht->eh_strategy_handler && !sht->eh_abort_handler &&
297             !sht->eh_device_reset_handler && !sht->eh_bus_reset_handler &&
298             !sht->eh_host_reset_handler) {
299                 printk(KERN_ERR "ERROR: SCSI host `%s' has no error handling\n"
300                                 "ERROR: This is not a safe way to run your "
301                                         "SCSI host\n"
302                                 "ERROR: The error handling must be added to "
303                                 "this driver\n", sht->proc_name);
304                 dump_stack();
305         }
306
307         shost = kmalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
308         if (!shost)
309                 return NULL;
310         memset(shost, 0, sizeof(struct Scsi_Host) + privsize);
311
312         spin_lock_init(&shost->default_lock);
313         scsi_assign_lock(shost, &shost->default_lock);
314         shost->shost_state = SHOST_CREATED;
315         INIT_LIST_HEAD(&shost->__devices);
316         INIT_LIST_HEAD(&shost->__targets);
317         INIT_LIST_HEAD(&shost->eh_cmd_q);
318         INIT_LIST_HEAD(&shost->starved_list);
319         init_waitqueue_head(&shost->host_wait);
320
321         init_MUTEX(&shost->scan_mutex);
322
323         shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
324         shost->dma_channel = 0xff;
325
326         /* These three are default values which can be overridden */
327         shost->max_channel = 0;
328         shost->max_id = 8;
329         shost->max_lun = 8;
330
331         /* Give each shost a default transportt */
332         shost->transportt = &blank_transport_template;
333
334         /*
335          * All drivers right now should be able to handle 12 byte
336          * commands.  Every so often there are requests for 16 byte
337          * commands, but individual low-level drivers need to certify that
338          * they actually do something sensible with such commands.
339          */
340         shost->max_cmd_len = 12;
341         shost->hostt = sht;
342         shost->this_id = sht->this_id;
343         shost->can_queue = sht->can_queue;
344         shost->sg_tablesize = sht->sg_tablesize;
345         shost->cmd_per_lun = sht->cmd_per_lun;
346         shost->unchecked_isa_dma = sht->unchecked_isa_dma;
347         shost->use_clustering = sht->use_clustering;
348         shost->ordered_flush = sht->ordered_flush;
349         shost->ordered_tag = sht->ordered_tag;
350
351         /*
352          * hosts/devices that do queueing must support ordered tags
353          */
354         if (shost->can_queue > 1 && shost->ordered_flush) {
355                 printk(KERN_ERR "scsi: ordered flushes don't support queueing\n");
356                 shost->ordered_flush = 0;
357         }
358
359         if (sht->max_host_blocked)
360                 shost->max_host_blocked = sht->max_host_blocked;
361         else
362                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
363
364         /*
365          * If the driver imposes no hard sector transfer limit, start at
366          * machine infinity initially.
367          */
368         if (sht->max_sectors)
369                 shost->max_sectors = sht->max_sectors;
370         else
371                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
372
373         /*
374          * assume a 4GB boundary, if not set
375          */
376         if (sht->dma_boundary)
377                 shost->dma_boundary = sht->dma_boundary;
378         else
379                 shost->dma_boundary = 0xffffffff;
380
381         rval = scsi_setup_command_freelist(shost);
382         if (rval)
383                 goto fail_kfree;
384
385         device_initialize(&shost->shost_gendev);
386         snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",
387                 shost->host_no);
388         shost->shost_gendev.release = scsi_host_dev_release;
389
390         class_device_initialize(&shost->shost_classdev);
391         shost->shost_classdev.dev = &shost->shost_gendev;
392         shost->shost_classdev.class = &shost_class;
393         snprintf(shost->shost_classdev.class_id, BUS_ID_SIZE, "host%d",
394                   shost->host_no);
395
396         shost->ehandler = kthread_run(scsi_error_handler, shost,
397                         "scsi_eh_%d", shost->host_no);
398         if (IS_ERR(shost->ehandler)) {
399                 rval = PTR_ERR(shost->ehandler);
400                 goto fail_destroy_freelist;
401         }
402
403         scsi_proc_hostdir_add(shost->hostt);
404         return shost;
405
406  fail_destroy_freelist:
407         scsi_destroy_command_freelist(shost);
408  fail_kfree:
409         kfree(shost);
410         return NULL;
411 }
412 EXPORT_SYMBOL(scsi_host_alloc);
413
414 struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
415 {
416         struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
417
418         if (!sht->detect) {
419                 printk(KERN_WARNING "scsi_register() called on new-style "
420                                     "template for driver %s\n", sht->name);
421                 dump_stack();
422         }
423
424         if (shost)
425                 list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
426         return shost;
427 }
428 EXPORT_SYMBOL(scsi_register);
429
430 void scsi_unregister(struct Scsi_Host *shost)
431 {
432         list_del(&shost->sht_legacy_list);
433         scsi_host_put(shost);
434 }
435 EXPORT_SYMBOL(scsi_unregister);
436
437 /**
438  * scsi_host_lookup - get a reference to a Scsi_Host by host no
439  *
440  * @hostnum:    host number to locate
441  *
442  * Return value:
443  *      A pointer to located Scsi_Host or NULL.
444  **/
445 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
446 {
447         struct class *class = &shost_class;
448         struct class_device *cdev;
449         struct Scsi_Host *shost = ERR_PTR(-ENXIO), *p;
450
451         down_read(&class->subsys.rwsem);
452         list_for_each_entry(cdev, &class->children, node) {
453                 p = class_to_shost(cdev);
454                 if (p->host_no == hostnum) {
455                         shost = scsi_host_get(p);
456                         break;
457                 }
458         }
459         up_read(&class->subsys.rwsem);
460
461         return shost;
462 }
463 EXPORT_SYMBOL(scsi_host_lookup);
464
465 /**
466  * scsi_host_get - inc a Scsi_Host ref count
467  * @shost:      Pointer to Scsi_Host to inc.
468  **/
469 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
470 {
471         if ((shost->shost_state == SHOST_DEL) ||
472                 !get_device(&shost->shost_gendev))
473                 return NULL;
474         return shost;
475 }
476 EXPORT_SYMBOL(scsi_host_get);
477
478 /**
479  * scsi_host_put - dec a Scsi_Host ref count
480  * @shost:      Pointer to Scsi_Host to dec.
481  **/
482 void scsi_host_put(struct Scsi_Host *shost)
483 {
484         put_device(&shost->shost_gendev);
485 }
486 EXPORT_SYMBOL(scsi_host_put);
487
488 int scsi_init_hosts(void)
489 {
490         return class_register(&shost_class);
491 }
492
493 void scsi_exit_hosts(void)
494 {
495         class_unregister(&shost_class);
496 }
497
498 int scsi_is_host_device(const struct device *dev)
499 {
500         return dev->release == scsi_host_dev_release;
501 }
502 EXPORT_SYMBOL(scsi_is_host_device);
503
504 /**
505  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
506  * @shost:      Pointer to Scsi_Host.
507  * @work:       Work to queue for execution.
508  *
509  * Return value:
510  *      0 on success / != 0 for error
511  **/
512 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
513 {
514         if (unlikely(!shost->work_q)) {
515                 printk(KERN_ERR
516                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
517                         "when no workqueue created.\n", shost->hostt->name);
518                 dump_stack();
519
520                 return -EINVAL;
521         }
522
523         return queue_work(shost->work_q, work);
524 }
525 EXPORT_SYMBOL_GPL(scsi_queue_work);
526
527 /**
528  * scsi_flush_work - Flush a Scsi_Host's workqueue.
529  * @shost:      Pointer to Scsi_Host.
530  **/
531 void scsi_flush_work(struct Scsi_Host *shost)
532 {
533         if (!shost->work_q) {
534                 printk(KERN_ERR
535                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
536                         "when no workqueue created.\n", shost->hostt->name);
537                 dump_stack();
538                 return;
539         }
540
541         flush_workqueue(shost->work_q);
542 }
543 EXPORT_SYMBOL_GPL(scsi_flush_work);