[SCSI] fcoe: fix fcoe module ref counting
[linux-2.6.git] / drivers / scsi / scsi_netlink.c
1 /*
2  *  scsi_netlink.c  - SCSI Transport Netlink Interface
3  *
4  *  Copyright (C) 2006   James Smart, Emulex Corporation
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, write to the Free Software
18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  *
20  */
21 #include <linux/time.h>
22 #include <linux/jiffies.h>
23 #include <linux/security.h>
24 #include <linux/delay.h>
25 #include <linux/slab.h>
26 #include <net/sock.h>
27 #include <net/netlink.h>
28
29 #include <scsi/scsi_netlink.h>
30 #include "scsi_priv.h"
31
32 struct sock *scsi_nl_sock = NULL;
33 EXPORT_SYMBOL_GPL(scsi_nl_sock);
34
35 static DEFINE_SPINLOCK(scsi_nl_lock);
36 static struct list_head scsi_nl_drivers;
37
38 static u32      scsi_nl_state;
39 #define STATE_EHANDLER_BSY              0x00000001
40
41 struct scsi_nl_transport {
42         int (*msg_handler)(struct sk_buff *);
43         void (*event_handler)(struct notifier_block *, unsigned long, void *);
44         unsigned int refcnt;
45         int flags;
46 };
47
48 /* flags values (bit flags) */
49 #define HANDLER_DELETING                0x1
50
51 static struct scsi_nl_transport transports[SCSI_NL_MAX_TRANSPORTS] =
52         { {NULL, }, };
53
54
55 struct scsi_nl_drvr {
56         struct list_head next;
57         int (*dmsg_handler)(struct Scsi_Host *shost, void *payload,
58                                  u32 len, u32 pid);
59         void (*devt_handler)(struct notifier_block *nb,
60                                  unsigned long event, void *notify_ptr);
61         struct scsi_host_template *hostt;
62         u64 vendor_id;
63         unsigned int refcnt;
64         int flags;
65 };
66
67
68
69 /**
70  * scsi_nl_rcv_msg - Receive message handler.
71  * @skb:                socket receive buffer
72  *
73  * Description: Extracts message from a receive buffer.
74  *    Validates message header and calls appropriate transport message handler
75  *
76  *
77  **/
78 static void
79 scsi_nl_rcv_msg(struct sk_buff *skb)
80 {
81         struct nlmsghdr *nlh;
82         struct scsi_nl_hdr *hdr;
83         unsigned long flags;
84         u32 rlen;
85         int err, tport;
86
87         while (skb->len >= NLMSG_SPACE(0)) {
88                 err = 0;
89
90                 nlh = nlmsg_hdr(skb);
91                 if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
92                     (skb->len < nlh->nlmsg_len)) {
93                         printk(KERN_WARNING "%s: discarding partial skb\n",
94                                  __func__);
95                         return;
96                 }
97
98                 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
99                 if (rlen > skb->len)
100                         rlen = skb->len;
101
102                 if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
103                         err = -EBADMSG;
104                         goto next_msg;
105                 }
106
107                 hdr = NLMSG_DATA(nlh);
108                 if ((hdr->version != SCSI_NL_VERSION) ||
109                     (hdr->magic != SCSI_NL_MAGIC)) {
110                         err = -EPROTOTYPE;
111                         goto next_msg;
112                 }
113
114                 if (security_netlink_recv(skb, CAP_SYS_ADMIN)) {
115                         err = -EPERM;
116                         goto next_msg;
117                 }
118
119                 if (nlh->nlmsg_len < (sizeof(*nlh) + hdr->msglen)) {
120                         printk(KERN_WARNING "%s: discarding partial message\n",
121                                  __func__);
122                         goto next_msg;
123                 }
124
125                 /*
126                  * Deliver message to the appropriate transport
127                  */
128                 spin_lock_irqsave(&scsi_nl_lock, flags);
129
130                 tport = hdr->transport;
131                 if ((tport < SCSI_NL_MAX_TRANSPORTS) &&
132                     !(transports[tport].flags & HANDLER_DELETING) &&
133                     (transports[tport].msg_handler)) {
134                         transports[tport].refcnt++;
135                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
136                         err = transports[tport].msg_handler(skb);
137                         spin_lock_irqsave(&scsi_nl_lock, flags);
138                         transports[tport].refcnt--;
139                 } else
140                         err = -ENOENT;
141
142                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
143
144 next_msg:
145                 if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
146                         netlink_ack(skb, nlh, err);
147
148                 skb_pull(skb, rlen);
149         }
150 }
151
152
153 /**
154  * scsi_nl_rcv_event - Event handler for a netlink socket.
155  * @this:               event notifier block
156  * @event:              event type
157  * @ptr:                event payload
158  *
159  **/
160 static int
161 scsi_nl_rcv_event(struct notifier_block *this, unsigned long event, void *ptr)
162 {
163         struct netlink_notify *n = ptr;
164         struct scsi_nl_drvr *driver;
165         unsigned long flags;
166         int tport;
167
168         if (n->protocol != NETLINK_SCSITRANSPORT)
169                 return NOTIFY_DONE;
170
171         spin_lock_irqsave(&scsi_nl_lock, flags);
172         scsi_nl_state |= STATE_EHANDLER_BSY;
173
174         /*
175          * Pass event on to any transports that may be listening
176          */
177         for (tport = 0; tport < SCSI_NL_MAX_TRANSPORTS; tport++) {
178                 if (!(transports[tport].flags & HANDLER_DELETING) &&
179                     (transports[tport].event_handler)) {
180                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
181                         transports[tport].event_handler(this, event, ptr);
182                         spin_lock_irqsave(&scsi_nl_lock, flags);
183                 }
184         }
185
186         /*
187          * Pass event on to any drivers that may be listening
188          */
189         list_for_each_entry(driver, &scsi_nl_drivers, next) {
190                 if (!(driver->flags & HANDLER_DELETING) &&
191                     (driver->devt_handler)) {
192                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
193                         driver->devt_handler(this, event, ptr);
194                         spin_lock_irqsave(&scsi_nl_lock, flags);
195                 }
196         }
197
198         scsi_nl_state &= ~STATE_EHANDLER_BSY;
199         spin_unlock_irqrestore(&scsi_nl_lock, flags);
200
201         return NOTIFY_DONE;
202 }
203
204 static struct notifier_block scsi_netlink_notifier = {
205         .notifier_call  = scsi_nl_rcv_event,
206 };
207
208
209 /*
210  * GENERIC SCSI transport receive and event handlers
211  */
212
213 /**
214  * scsi_generic_msg_handler - receive message handler for GENERIC transport messages
215  * @skb:                socket receive buffer
216  **/
217 static int
218 scsi_generic_msg_handler(struct sk_buff *skb)
219 {
220         struct nlmsghdr *nlh = nlmsg_hdr(skb);
221         struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
222         struct scsi_nl_drvr *driver;
223         struct Scsi_Host *shost;
224         unsigned long flags;
225         int err = 0, match, pid;
226
227         pid = NETLINK_CREDS(skb)->pid;
228
229         switch (snlh->msgtype) {
230         case SCSI_NL_SHOST_VENDOR:
231                 {
232                 struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);
233
234                 /* Locate the driver that corresponds to the message */
235                 spin_lock_irqsave(&scsi_nl_lock, flags);
236                 match = 0;
237                 list_for_each_entry(driver, &scsi_nl_drivers, next) {
238                         if (driver->vendor_id == msg->vendor_id) {
239                                 match = 1;
240                                 break;
241                         }
242                 }
243
244                 if ((!match) || (!driver->dmsg_handler)) {
245                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
246                         err = -ESRCH;
247                         goto rcv_exit;
248                 }
249
250                 if (driver->flags & HANDLER_DELETING) {
251                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
252                         err = -ESHUTDOWN;
253                         goto rcv_exit;
254                 }
255
256                 driver->refcnt++;
257                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
258
259
260                 /* if successful, scsi_host_lookup takes a shost reference */
261                 shost = scsi_host_lookup(msg->host_no);
262                 if (!shost) {
263                         err = -ENODEV;
264                         goto driver_exit;
265                 }
266
267                 /* is this host owned by the vendor ? */
268                 if (shost->hostt != driver->hostt) {
269                         err = -EINVAL;
270                         goto vendormsg_put;
271                 }
272
273                 /* pass message on to the driver */
274                 err = driver->dmsg_handler(shost, (void *)&msg[1],
275                                          msg->vmsg_datalen, pid);
276
277 vendormsg_put:
278                 /* release reference by scsi_host_lookup */
279                 scsi_host_put(shost);
280
281 driver_exit:
282                 /* release our own reference on the registration object */
283                 spin_lock_irqsave(&scsi_nl_lock, flags);
284                 driver->refcnt--;
285                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
286                 break;
287                 }
288
289         default:
290                 err = -EBADR;
291                 break;
292         }
293
294 rcv_exit:
295         if (err)
296                 printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
297                          __func__, snlh->msgtype, err);
298         return err;
299 }
300
301
302 /**
303  * scsi_nl_add_transport -
304  *    Registers message and event handlers for a transport. Enables
305  *    receipt of netlink messages and events to a transport.
306  *
307  * @tport:              transport registering handlers
308  * @msg_handler:        receive message handler callback
309  * @event_handler:      receive event handler callback
310  **/
311 int
312 scsi_nl_add_transport(u8 tport,
313         int (*msg_handler)(struct sk_buff *),
314         void (*event_handler)(struct notifier_block *, unsigned long, void *))
315 {
316         unsigned long flags;
317         int err = 0;
318
319         if (tport >= SCSI_NL_MAX_TRANSPORTS)
320                 return -EINVAL;
321
322         spin_lock_irqsave(&scsi_nl_lock, flags);
323
324         if (scsi_nl_state & STATE_EHANDLER_BSY) {
325                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
326                 msleep(1);
327                 spin_lock_irqsave(&scsi_nl_lock, flags);
328         }
329
330         if (transports[tport].msg_handler || transports[tport].event_handler) {
331                 err = -EALREADY;
332                 goto register_out;
333         }
334
335         transports[tport].msg_handler = msg_handler;
336         transports[tport].event_handler = event_handler;
337         transports[tport].flags = 0;
338         transports[tport].refcnt = 0;
339
340 register_out:
341         spin_unlock_irqrestore(&scsi_nl_lock, flags);
342
343         return err;
344 }
345 EXPORT_SYMBOL_GPL(scsi_nl_add_transport);
346
347
348 /**
349  * scsi_nl_remove_transport -
350  *    Disable transport receiption of messages and events
351  *
352  * @tport:              transport deregistering handlers
353  *
354  **/
355 void
356 scsi_nl_remove_transport(u8 tport)
357 {
358         unsigned long flags;
359
360         spin_lock_irqsave(&scsi_nl_lock, flags);
361         if (scsi_nl_state & STATE_EHANDLER_BSY) {
362                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
363                 msleep(1);
364                 spin_lock_irqsave(&scsi_nl_lock, flags);
365         }
366
367         if (tport < SCSI_NL_MAX_TRANSPORTS) {
368                 transports[tport].flags |= HANDLER_DELETING;
369
370                 while (transports[tport].refcnt != 0) {
371                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
372                         schedule_timeout_uninterruptible(HZ/4);
373                         spin_lock_irqsave(&scsi_nl_lock, flags);
374                 }
375                 transports[tport].msg_handler = NULL;
376                 transports[tport].event_handler = NULL;
377                 transports[tport].flags = 0;
378         }
379
380         spin_unlock_irqrestore(&scsi_nl_lock, flags);
381
382         return;
383 }
384 EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);
385
386
387 /**
388  * scsi_nl_add_driver -
389  *    A driver is registering its interfaces for SCSI netlink messages
390  *
391  * @vendor_id:          A unique identification value for the driver.
392  * @hostt:              address of the driver's host template. Used
393  *                      to verify an shost is bound to the driver
394  * @nlmsg_handler:      receive message handler callback
395  * @nlevt_handler:      receive event handler callback
396  *
397  * Returns:
398  *   0 on Success
399  *   error result otherwise
400  **/
401 int
402 scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
403         int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
404                                  u32 len, u32 pid),
405         void (*nlevt_handler)(struct notifier_block *nb,
406                                  unsigned long event, void *notify_ptr))
407 {
408         struct scsi_nl_drvr *driver;
409         unsigned long flags;
410
411         driver = kzalloc(sizeof(*driver), GFP_KERNEL);
412         if (unlikely(!driver)) {
413                 printk(KERN_ERR "%s: allocation failure\n", __func__);
414                 return -ENOMEM;
415         }
416
417         driver->dmsg_handler = nlmsg_handler;
418         driver->devt_handler = nlevt_handler;
419         driver->hostt = hostt;
420         driver->vendor_id = vendor_id;
421
422         spin_lock_irqsave(&scsi_nl_lock, flags);
423         if (scsi_nl_state & STATE_EHANDLER_BSY) {
424                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
425                 msleep(1);
426                 spin_lock_irqsave(&scsi_nl_lock, flags);
427         }
428         list_add_tail(&driver->next, &scsi_nl_drivers);
429         spin_unlock_irqrestore(&scsi_nl_lock, flags);
430
431         return 0;
432 }
433 EXPORT_SYMBOL_GPL(scsi_nl_add_driver);
434
435
436 /**
437  * scsi_nl_remove_driver -
438  *    An driver is unregistering with the SCSI netlink messages
439  *
440  * @vendor_id:          The unique identification value for the driver.
441  **/
442 void
443 scsi_nl_remove_driver(u64 vendor_id)
444 {
445         struct scsi_nl_drvr *driver;
446         unsigned long flags;
447
448         spin_lock_irqsave(&scsi_nl_lock, flags);
449         if (scsi_nl_state & STATE_EHANDLER_BSY) {
450                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
451                 msleep(1);
452                 spin_lock_irqsave(&scsi_nl_lock, flags);
453         }
454
455         list_for_each_entry(driver, &scsi_nl_drivers, next) {
456                 if (driver->vendor_id == vendor_id) {
457                         driver->flags |= HANDLER_DELETING;
458                         while (driver->refcnt != 0) {
459                                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
460                                 schedule_timeout_uninterruptible(HZ/4);
461                                 spin_lock_irqsave(&scsi_nl_lock, flags);
462                         }
463                         list_del(&driver->next);
464                         kfree(driver);
465                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
466                         return;
467                 }
468         }
469
470         spin_unlock_irqrestore(&scsi_nl_lock, flags);
471
472         printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
473                __func__, (unsigned long long)vendor_id);
474         return;
475 }
476 EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
477
478
479 /**
480  * scsi_netlink_init - Called by SCSI subsystem to intialize
481  *      the SCSI transport netlink interface
482  *
483  **/
484 void
485 scsi_netlink_init(void)
486 {
487         int error;
488
489         INIT_LIST_HEAD(&scsi_nl_drivers);
490
491         error = netlink_register_notifier(&scsi_netlink_notifier);
492         if (error) {
493                 printk(KERN_ERR "%s: register of event handler failed - %d\n",
494                                 __func__, error);
495                 return;
496         }
497
498         scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
499                                 SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
500                                 THIS_MODULE);
501         if (!scsi_nl_sock) {
502                 printk(KERN_ERR "%s: register of recieve handler failed\n",
503                                 __func__);
504                 netlink_unregister_notifier(&scsi_netlink_notifier);
505                 return;
506         }
507
508         /* Register the entry points for the generic SCSI transport */
509         error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
510                                 scsi_generic_msg_handler, NULL);
511         if (error)
512                 printk(KERN_ERR "%s: register of GENERIC transport handler"
513                                 "  failed - %d\n", __func__, error);
514         return;
515 }
516
517
518 /**
519  * scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
520  *
521  **/
522 void
523 scsi_netlink_exit(void)
524 {
525         scsi_nl_remove_transport(SCSI_NL_TRANSPORT);
526
527         if (scsi_nl_sock) {
528                 netlink_kernel_release(scsi_nl_sock);
529                 netlink_unregister_notifier(&scsi_netlink_notifier);
530         }
531
532         return;
533 }
534
535
536 /*
537  * Exported Interfaces
538  */
539
540 /**
541  * scsi_nl_send_transport_msg -
542  *    Generic function to send a single message from a SCSI transport to
543  *    a single process
544  *
545  * @pid:                receiving pid
546  * @hdr:                message payload
547  *
548  **/
549 void
550 scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
551 {
552         struct sk_buff *skb;
553         struct nlmsghdr *nlh;
554         const char *fn;
555         char *datab;
556         u32 len, skblen;
557         int err;
558
559         if (!scsi_nl_sock) {
560                 err = -ENOENT;
561                 fn = "netlink socket";
562                 goto msg_fail;
563         }
564
565         len = NLMSG_SPACE(hdr->msglen);
566         skblen = NLMSG_SPACE(len);
567
568         skb = alloc_skb(skblen, GFP_KERNEL);
569         if (!skb) {
570                 err = -ENOBUFS;
571                 fn = "alloc_skb";
572                 goto msg_fail;
573         }
574
575         nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
576         if (!nlh) {
577                 err = -ENOBUFS;
578                 fn = "nlmsg_put";
579                 goto msg_fail_skb;
580         }
581         datab = NLMSG_DATA(nlh);
582         memcpy(datab, hdr, hdr->msglen);
583
584         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
585         if (err < 0) {
586                 fn = "nlmsg_unicast";
587                 /* nlmsg_unicast already kfree_skb'd */
588                 goto msg_fail;
589         }
590
591         return;
592
593 msg_fail_skb:
594         kfree_skb(skb);
595 msg_fail:
596         printk(KERN_WARNING
597                 "%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
598                 "msglen %d: %s : err %d\n",
599                 __func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
600                 fn, err);
601         return;
602 }
603 EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);
604
605
606 /**
607  * scsi_nl_send_vendor_msg - called to send a shost vendor unique message
608  *                      to a specific process id.
609  *
610  * @pid:                process id of the receiver
611  * @host_no:            host # sending the message
612  * @vendor_id:          unique identifier for the driver's vendor
613  * @data_len:           amount, in bytes, of vendor unique payload data
614  * @data_buf:           pointer to vendor unique data buffer
615  *
616  * Returns:
617  *   0 on successful return
618  *   otherwise, failing error code
619  *
620  * Notes:
621  *      This routine assumes no locks are held on entry.
622  */
623 int
624 scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
625                          char *data_buf, u32 data_len)
626 {
627         struct sk_buff *skb;
628         struct nlmsghdr *nlh;
629         struct scsi_nl_host_vendor_msg *msg;
630         u32 len, skblen;
631         int err;
632
633         if (!scsi_nl_sock) {
634                 err = -ENOENT;
635                 goto send_vendor_fail;
636         }
637
638         len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
639         skblen = NLMSG_SPACE(len);
640
641         skb = alloc_skb(skblen, GFP_KERNEL);
642         if (!skb) {
643                 err = -ENOBUFS;
644                 goto send_vendor_fail;
645         }
646
647         nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
648                                 skblen - sizeof(*nlh), 0);
649         if (!nlh) {
650                 err = -ENOBUFS;
651                 goto send_vendor_fail_skb;
652         }
653         msg = NLMSG_DATA(nlh);
654
655         INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
656                                 SCSI_NL_SHOST_VENDOR, len);
657         msg->vendor_id = vendor_id;
658         msg->host_no = host_no;
659         msg->vmsg_datalen = data_len;   /* bytes */
660         memcpy(&msg[1], data_buf, data_len);
661
662         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
663         if (err)
664                 /* nlmsg_multicast already kfree_skb'd */
665                 goto send_vendor_fail;
666
667         return 0;
668
669 send_vendor_fail_skb:
670         kfree_skb(skb);
671 send_vendor_fail:
672         printk(KERN_WARNING
673                 "%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
674                 __func__, host_no, err);
675         return err;
676 }
677 EXPORT_SYMBOL(scsi_nl_send_vendor_msg);
678
679