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Linux/block/bsg.c

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  1 /*
  2  * bsg.c - block layer implementation of the sg v4 interface
  3  *
  4  * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
  5  * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
  6  *
  7  *  This file is subject to the terms and conditions of the GNU General Public
  8  *  License version 2.  See the file "COPYING" in the main directory of this
  9  *  archive for more details.
 10  *
 11  */
 12 #include <linux/module.h>
 13 #include <linux/init.h>
 14 #include <linux/file.h>
 15 #include <linux/blkdev.h>
 16 #include <linux/poll.h>
 17 #include <linux/cdev.h>
 18 #include <linux/jiffies.h>
 19 #include <linux/percpu.h>
 20 #include <linux/uio.h>
 21 #include <linux/idr.h>
 22 #include <linux/bsg.h>
 23 #include <linux/slab.h>
 24 
 25 #include <scsi/scsi.h>
 26 #include <scsi/scsi_ioctl.h>
 27 #include <scsi/scsi_cmnd.h>
 28 #include <scsi/scsi_device.h>
 29 #include <scsi/scsi_driver.h>
 30 #include <scsi/sg.h>
 31 
 32 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
 33 #define BSG_VERSION     "0.4"
 34 
 35 struct bsg_device {
 36         struct request_queue *queue;
 37         spinlock_t lock;
 38         struct list_head busy_list;
 39         struct list_head done_list;
 40         struct hlist_node dev_list;
 41         atomic_t ref_count;
 42         int queued_cmds;
 43         int done_cmds;
 44         wait_queue_head_t wq_done;
 45         wait_queue_head_t wq_free;
 46         char name[20];
 47         int max_queue;
 48         unsigned long flags;
 49 };
 50 
 51 enum {
 52         BSG_F_BLOCK             = 1,
 53 };
 54 
 55 #define BSG_DEFAULT_CMDS        64
 56 #define BSG_MAX_DEVS            32768
 57 
 58 #undef BSG_DEBUG
 59 
 60 #ifdef BSG_DEBUG
 61 #define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
 62 #else
 63 #define dprintk(fmt, args...)
 64 #endif
 65 
 66 static DEFINE_MUTEX(bsg_mutex);
 67 static DEFINE_IDR(bsg_minor_idr);
 68 
 69 #define BSG_LIST_ARRAY_SIZE     8
 70 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
 71 
 72 static struct class *bsg_class;
 73 static int bsg_major;
 74 
 75 static struct kmem_cache *bsg_cmd_cachep;
 76 
 77 /*
 78  * our internal command type
 79  */
 80 struct bsg_command {
 81         struct bsg_device *bd;
 82         struct list_head list;
 83         struct request *rq;
 84         struct bio *bio;
 85         struct bio *bidi_bio;
 86         int err;
 87         struct sg_io_v4 hdr;
 88         char sense[SCSI_SENSE_BUFFERSIZE];
 89 };
 90 
 91 static void bsg_free_command(struct bsg_command *bc)
 92 {
 93         struct bsg_device *bd = bc->bd;
 94         unsigned long flags;
 95 
 96         kmem_cache_free(bsg_cmd_cachep, bc);
 97 
 98         spin_lock_irqsave(&bd->lock, flags);
 99         bd->queued_cmds--;
100         spin_unlock_irqrestore(&bd->lock, flags);
101 
102         wake_up(&bd->wq_free);
103 }
104 
105 static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
106 {
107         struct bsg_command *bc = ERR_PTR(-EINVAL);
108 
109         spin_lock_irq(&bd->lock);
110 
111         if (bd->queued_cmds >= bd->max_queue)
112                 goto out;
113 
114         bd->queued_cmds++;
115         spin_unlock_irq(&bd->lock);
116 
117         bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
118         if (unlikely(!bc)) {
119                 spin_lock_irq(&bd->lock);
120                 bd->queued_cmds--;
121                 bc = ERR_PTR(-ENOMEM);
122                 goto out;
123         }
124 
125         bc->bd = bd;
126         INIT_LIST_HEAD(&bc->list);
127         dprintk("%s: returning free cmd %p\n", bd->name, bc);
128         return bc;
129 out:
130         spin_unlock_irq(&bd->lock);
131         return bc;
132 }
133 
134 static inline struct hlist_head *bsg_dev_idx_hash(int index)
135 {
136         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
137 }
138 
139 static int bsg_io_schedule(struct bsg_device *bd)
140 {
141         DEFINE_WAIT(wait);
142         int ret = 0;
143 
144         spin_lock_irq(&bd->lock);
145 
146         BUG_ON(bd->done_cmds > bd->queued_cmds);
147 
148         /*
149          * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
150          * work to do", even though we return -ENOSPC after this same test
151          * during bsg_write() -- there, it means our buffer can't have more
152          * bsg_commands added to it, thus has no space left.
153          */
154         if (bd->done_cmds == bd->queued_cmds) {
155                 ret = -ENODATA;
156                 goto unlock;
157         }
158 
159         if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
160                 ret = -EAGAIN;
161                 goto unlock;
162         }
163 
164         prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
165         spin_unlock_irq(&bd->lock);
166         io_schedule();
167         finish_wait(&bd->wq_done, &wait);
168 
169         return ret;
170 unlock:
171         spin_unlock_irq(&bd->lock);
172         return ret;
173 }
174 
175 static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
176                                 struct sg_io_v4 *hdr, struct bsg_device *bd,
177                                 fmode_t has_write_perm)
178 {
179         if (hdr->request_len > BLK_MAX_CDB) {
180                 rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
181                 if (!rq->cmd)
182                         return -ENOMEM;
183         }
184 
185         if (copy_from_user(rq->cmd, (void __user *)(unsigned long)hdr->request,
186                            hdr->request_len))
187                 return -EFAULT;
188 
189         if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
190                 if (blk_verify_command(rq->cmd, has_write_perm))
191                         return -EPERM;
192         } else if (!capable(CAP_SYS_RAWIO))
193                 return -EPERM;
194 
195         /*
196          * fill in request structure
197          */
198         rq->cmd_len = hdr->request_len;
199         rq->cmd_type = REQ_TYPE_BLOCK_PC;
200 
201         rq->timeout = msecs_to_jiffies(hdr->timeout);
202         if (!rq->timeout)
203                 rq->timeout = q->sg_timeout;
204         if (!rq->timeout)
205                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
206         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
207                 rq->timeout = BLK_MIN_SG_TIMEOUT;
208 
209         return 0;
210 }
211 
212 /*
213  * Check if sg_io_v4 from user is allowed and valid
214  */
215 static int
216 bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
217 {
218         int ret = 0;
219 
220         if (hdr->guard != 'Q')
221                 return -EINVAL;
222 
223         switch (hdr->protocol) {
224         case BSG_PROTOCOL_SCSI:
225                 switch (hdr->subprotocol) {
226                 case BSG_SUB_PROTOCOL_SCSI_CMD:
227                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
228                         break;
229                 default:
230                         ret = -EINVAL;
231                 }
232                 break;
233         default:
234                 ret = -EINVAL;
235         }
236 
237         *rw = hdr->dout_xfer_len ? WRITE : READ;
238         return ret;
239 }
240 
241 /*
242  * map sg_io_v4 to a request.
243  */
244 static struct request *
245 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
246             u8 *sense)
247 {
248         struct request_queue *q = bd->queue;
249         struct request *rq, *next_rq = NULL;
250         int ret, rw;
251         unsigned int dxfer_len;
252         void __user *dxferp = NULL;
253         struct bsg_class_device *bcd = &q->bsg_dev;
254 
255         /* if the LLD has been removed then the bsg_unregister_queue will
256          * eventually be called and the class_dev was freed, so we can no
257          * longer use this request_queue. Return no such address.
258          */
259         if (!bcd->class_dev)
260                 return ERR_PTR(-ENXIO);
261 
262         dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
263                 hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
264                 hdr->din_xfer_len);
265 
266         ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
267         if (ret)
268                 return ERR_PTR(ret);
269 
270         /*
271          * map scatter-gather elements separately and string them to request
272          */
273         rq = blk_get_request(q, rw, GFP_KERNEL);
274         if (!rq)
275                 return ERR_PTR(-ENOMEM);
276         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
277         if (ret)
278                 goto out;
279 
280         if (rw == WRITE && hdr->din_xfer_len) {
281                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
282                         ret = -EOPNOTSUPP;
283                         goto out;
284                 }
285 
286                 next_rq = blk_get_request(q, READ, GFP_KERNEL);
287                 if (!next_rq) {
288                         ret = -ENOMEM;
289                         goto out;
290                 }
291                 rq->next_rq = next_rq;
292                 next_rq->cmd_type = rq->cmd_type;
293 
294                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
295                 ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
296                                        hdr->din_xfer_len, GFP_KERNEL);
297                 if (ret)
298                         goto out;
299         }
300 
301         if (hdr->dout_xfer_len) {
302                 dxfer_len = hdr->dout_xfer_len;
303                 dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
304         } else if (hdr->din_xfer_len) {
305                 dxfer_len = hdr->din_xfer_len;
306                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
307         } else
308                 dxfer_len = 0;
309 
310         if (dxfer_len) {
311                 ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
312                                       GFP_KERNEL);
313                 if (ret)
314                         goto out;
315         }
316 
317         rq->sense = sense;
318         rq->sense_len = 0;
319 
320         return rq;
321 out:
322         if (rq->cmd != rq->__cmd)
323                 kfree(rq->cmd);
324         blk_put_request(rq);
325         if (next_rq) {
326                 blk_rq_unmap_user(next_rq->bio);
327                 blk_put_request(next_rq);
328         }
329         return ERR_PTR(ret);
330 }
331 
332 /*
333  * async completion call-back from the block layer, when scsi/ide/whatever
334  * calls end_that_request_last() on a request
335  */
336 static void bsg_rq_end_io(struct request *rq, int uptodate)
337 {
338         struct bsg_command *bc = rq->end_io_data;
339         struct bsg_device *bd = bc->bd;
340         unsigned long flags;
341 
342         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
343                 bd->name, rq, bc, bc->bio, uptodate);
344 
345         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
346 
347         spin_lock_irqsave(&bd->lock, flags);
348         list_move_tail(&bc->list, &bd->done_list);
349         bd->done_cmds++;
350         spin_unlock_irqrestore(&bd->lock, flags);
351 
352         wake_up(&bd->wq_done);
353 }
354 
355 /*
356  * do final setup of a 'bc' and submit the matching 'rq' to the block
357  * layer for io
358  */
359 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
360                             struct bsg_command *bc, struct request *rq)
361 {
362         int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
363 
364         /*
365          * add bc command to busy queue and submit rq for io
366          */
367         bc->rq = rq;
368         bc->bio = rq->bio;
369         if (rq->next_rq)
370                 bc->bidi_bio = rq->next_rq->bio;
371         bc->hdr.duration = jiffies;
372         spin_lock_irq(&bd->lock);
373         list_add_tail(&bc->list, &bd->busy_list);
374         spin_unlock_irq(&bd->lock);
375 
376         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
377 
378         rq->end_io_data = bc;
379         blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
380 }
381 
382 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
383 {
384         struct bsg_command *bc = NULL;
385 
386         spin_lock_irq(&bd->lock);
387         if (bd->done_cmds) {
388                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
389                 list_del(&bc->list);
390                 bd->done_cmds--;
391         }
392         spin_unlock_irq(&bd->lock);
393 
394         return bc;
395 }
396 
397 /*
398  * Get a finished command from the done list
399  */
400 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
401 {
402         struct bsg_command *bc;
403         int ret;
404 
405         do {
406                 bc = bsg_next_done_cmd(bd);
407                 if (bc)
408                         break;
409 
410                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
411                         bc = ERR_PTR(-EAGAIN);
412                         break;
413                 }
414 
415                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
416                 if (ret) {
417                         bc = ERR_PTR(-ERESTARTSYS);
418                         break;
419                 }
420         } while (1);
421 
422         dprintk("%s: returning done %p\n", bd->name, bc);
423 
424         return bc;
425 }
426 
427 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
428                                     struct bio *bio, struct bio *bidi_bio)
429 {
430         int ret = 0;
431 
432         dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
433         /*
434          * fill in all the output members
435          */
436         hdr->device_status = rq->errors & 0xff;
437         hdr->transport_status = host_byte(rq->errors);
438         hdr->driver_status = driver_byte(rq->errors);
439         hdr->info = 0;
440         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
441                 hdr->info |= SG_INFO_CHECK;
442         hdr->response_len = 0;
443 
444         if (rq->sense_len && hdr->response) {
445                 int len = min_t(unsigned int, hdr->max_response_len,
446                                         rq->sense_len);
447 
448                 ret = copy_to_user((void __user *)(unsigned long)hdr->response,
449                                    rq->sense, len);
450                 if (!ret)
451                         hdr->response_len = len;
452                 else
453                         ret = -EFAULT;
454         }
455 
456         if (rq->next_rq) {
457                 hdr->dout_resid = rq->resid_len;
458                 hdr->din_resid = rq->next_rq->resid_len;
459                 blk_rq_unmap_user(bidi_bio);
460                 blk_put_request(rq->next_rq);
461         } else if (rq_data_dir(rq) == READ)
462                 hdr->din_resid = rq->resid_len;
463         else
464                 hdr->dout_resid = rq->resid_len;
465 
466         /*
467          * If the request generated a negative error number, return it
468          * (providing we aren't already returning an error); if it's
469          * just a protocol response (i.e. non negative), that gets
470          * processed above.
471          */
472         if (!ret && rq->errors < 0)
473                 ret = rq->errors;
474 
475         blk_rq_unmap_user(bio);
476         if (rq->cmd != rq->__cmd)
477                 kfree(rq->cmd);
478         blk_put_request(rq);
479 
480         return ret;
481 }
482 
483 static int bsg_complete_all_commands(struct bsg_device *bd)
484 {
485         struct bsg_command *bc;
486         int ret, tret;
487 
488         dprintk("%s: entered\n", bd->name);
489 
490         /*
491          * wait for all commands to complete
492          */
493         ret = 0;
494         do {
495                 ret = bsg_io_schedule(bd);
496                 /*
497                  * look for -ENODATA specifically -- we'll sometimes get
498                  * -ERESTARTSYS when we've taken a signal, but we can't
499                  * return until we're done freeing the queue, so ignore
500                  * it.  The signal will get handled when we're done freeing
501                  * the bsg_device.
502                  */
503         } while (ret != -ENODATA);
504 
505         /*
506          * discard done commands
507          */
508         ret = 0;
509         do {
510                 spin_lock_irq(&bd->lock);
511                 if (!bd->queued_cmds) {
512                         spin_unlock_irq(&bd->lock);
513                         break;
514                 }
515                 spin_unlock_irq(&bd->lock);
516 
517                 bc = bsg_get_done_cmd(bd);
518                 if (IS_ERR(bc))
519                         break;
520 
521                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
522                                                 bc->bidi_bio);
523                 if (!ret)
524                         ret = tret;
525 
526                 bsg_free_command(bc);
527         } while (1);
528 
529         return ret;
530 }
531 
532 static int
533 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
534            const struct iovec *iov, ssize_t *bytes_read)
535 {
536         struct bsg_command *bc;
537         int nr_commands, ret;
538 
539         if (count % sizeof(struct sg_io_v4))
540                 return -EINVAL;
541 
542         ret = 0;
543         nr_commands = count / sizeof(struct sg_io_v4);
544         while (nr_commands) {
545                 bc = bsg_get_done_cmd(bd);
546                 if (IS_ERR(bc)) {
547                         ret = PTR_ERR(bc);
548                         break;
549                 }
550 
551                 /*
552                  * this is the only case where we need to copy data back
553                  * after completing the request. so do that here,
554                  * bsg_complete_work() cannot do that for us
555                  */
556                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
557                                                bc->bidi_bio);
558 
559                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
560                         ret = -EFAULT;
561 
562                 bsg_free_command(bc);
563 
564                 if (ret)
565                         break;
566 
567                 buf += sizeof(struct sg_io_v4);
568                 *bytes_read += sizeof(struct sg_io_v4);
569                 nr_commands--;
570         }
571 
572         return ret;
573 }
574 
575 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
576 {
577         if (file->f_flags & O_NONBLOCK)
578                 clear_bit(BSG_F_BLOCK, &bd->flags);
579         else
580                 set_bit(BSG_F_BLOCK, &bd->flags);
581 }
582 
583 /*
584  * Check if the error is a "real" error that we should return.
585  */
586 static inline int err_block_err(int ret)
587 {
588         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
589                 return 1;
590 
591         return 0;
592 }
593 
594 static ssize_t
595 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
596 {
597         struct bsg_device *bd = file->private_data;
598         int ret;
599         ssize_t bytes_read;
600 
601         dprintk("%s: read %Zd bytes\n", bd->name, count);
602 
603         bsg_set_block(bd, file);
604 
605         bytes_read = 0;
606         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
607         *ppos = bytes_read;
608 
609         if (!bytes_read || err_block_err(ret))
610                 bytes_read = ret;
611 
612         return bytes_read;
613 }
614 
615 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
616                        size_t count, ssize_t *bytes_written,
617                        fmode_t has_write_perm)
618 {
619         struct bsg_command *bc;
620         struct request *rq;
621         int ret, nr_commands;
622 
623         if (count % sizeof(struct sg_io_v4))
624                 return -EINVAL;
625 
626         nr_commands = count / sizeof(struct sg_io_v4);
627         rq = NULL;
628         bc = NULL;
629         ret = 0;
630         while (nr_commands) {
631                 struct request_queue *q = bd->queue;
632 
633                 bc = bsg_alloc_command(bd);
634                 if (IS_ERR(bc)) {
635                         ret = PTR_ERR(bc);
636                         bc = NULL;
637                         break;
638                 }
639 
640                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
641                         ret = -EFAULT;
642                         break;
643                 }
644 
645                 /*
646                  * get a request, fill in the blanks, and add to request queue
647                  */
648                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
649                 if (IS_ERR(rq)) {
650                         ret = PTR_ERR(rq);
651                         rq = NULL;
652                         break;
653                 }
654 
655                 bsg_add_command(bd, q, bc, rq);
656                 bc = NULL;
657                 rq = NULL;
658                 nr_commands--;
659                 buf += sizeof(struct sg_io_v4);
660                 *bytes_written += sizeof(struct sg_io_v4);
661         }
662 
663         if (bc)
664                 bsg_free_command(bc);
665 
666         return ret;
667 }
668 
669 static ssize_t
670 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
671 {
672         struct bsg_device *bd = file->private_data;
673         ssize_t bytes_written;
674         int ret;
675 
676         dprintk("%s: write %Zd bytes\n", bd->name, count);
677 
678         bsg_set_block(bd, file);
679 
680         bytes_written = 0;
681         ret = __bsg_write(bd, buf, count, &bytes_written,
682                           file->f_mode & FMODE_WRITE);
683 
684         *ppos = bytes_written;
685 
686         /*
687          * return bytes written on non-fatal errors
688          */
689         if (!bytes_written || err_block_err(ret))
690                 bytes_written = ret;
691 
692         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
693         return bytes_written;
694 }
695 
696 static struct bsg_device *bsg_alloc_device(void)
697 {
698         struct bsg_device *bd;
699 
700         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
701         if (unlikely(!bd))
702                 return NULL;
703 
704         spin_lock_init(&bd->lock);
705 
706         bd->max_queue = BSG_DEFAULT_CMDS;
707 
708         INIT_LIST_HEAD(&bd->busy_list);
709         INIT_LIST_HEAD(&bd->done_list);
710         INIT_HLIST_NODE(&bd->dev_list);
711 
712         init_waitqueue_head(&bd->wq_free);
713         init_waitqueue_head(&bd->wq_done);
714         return bd;
715 }
716 
717 static void bsg_kref_release_function(struct kref *kref)
718 {
719         struct bsg_class_device *bcd =
720                 container_of(kref, struct bsg_class_device, ref);
721         struct device *parent = bcd->parent;
722 
723         if (bcd->release)
724                 bcd->release(bcd->parent);
725 
726         put_device(parent);
727 }
728 
729 static int bsg_put_device(struct bsg_device *bd)
730 {
731         int ret = 0, do_free;
732         struct request_queue *q = bd->queue;
733 
734         mutex_lock(&bsg_mutex);
735 
736         do_free = atomic_dec_and_test(&bd->ref_count);
737         if (!do_free) {
738                 mutex_unlock(&bsg_mutex);
739                 goto out;
740         }
741 
742         hlist_del(&bd->dev_list);
743         mutex_unlock(&bsg_mutex);
744 
745         dprintk("%s: tearing down\n", bd->name);
746 
747         /*
748          * close can always block
749          */
750         set_bit(BSG_F_BLOCK, &bd->flags);
751 
752         /*
753          * correct error detection baddies here again. it's the responsibility
754          * of the app to properly reap commands before close() if it wants
755          * fool-proof error detection
756          */
757         ret = bsg_complete_all_commands(bd);
758 
759         kfree(bd);
760 out:
761         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
762         if (do_free)
763                 blk_put_queue(q);
764         return ret;
765 }
766 
767 static struct bsg_device *bsg_add_device(struct inode *inode,
768                                          struct request_queue *rq,
769                                          struct file *file)
770 {
771         struct bsg_device *bd;
772 #ifdef BSG_DEBUG
773         unsigned char buf[32];
774 #endif
775         if (!blk_get_queue(rq))
776                 return ERR_PTR(-ENXIO);
777 
778         bd = bsg_alloc_device();
779         if (!bd) {
780                 blk_put_queue(rq);
781                 return ERR_PTR(-ENOMEM);
782         }
783 
784         bd->queue = rq;
785 
786         bsg_set_block(bd, file);
787 
788         atomic_set(&bd->ref_count, 1);
789         mutex_lock(&bsg_mutex);
790         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
791 
792         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
793         dprintk("bound to <%s>, max queue %d\n",
794                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
795 
796         mutex_unlock(&bsg_mutex);
797         return bd;
798 }
799 
800 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
801 {
802         struct bsg_device *bd;
803 
804         mutex_lock(&bsg_mutex);
805 
806         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
807                 if (bd->queue == q) {
808                         atomic_inc(&bd->ref_count);
809                         goto found;
810                 }
811         }
812         bd = NULL;
813 found:
814         mutex_unlock(&bsg_mutex);
815         return bd;
816 }
817 
818 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
819 {
820         struct bsg_device *bd;
821         struct bsg_class_device *bcd;
822 
823         /*
824          * find the class device
825          */
826         mutex_lock(&bsg_mutex);
827         bcd = idr_find(&bsg_minor_idr, iminor(inode));
828         if (bcd)
829                 kref_get(&bcd->ref);
830         mutex_unlock(&bsg_mutex);
831 
832         if (!bcd)
833                 return ERR_PTR(-ENODEV);
834 
835         bd = __bsg_get_device(iminor(inode), bcd->queue);
836         if (bd)
837                 return bd;
838 
839         bd = bsg_add_device(inode, bcd->queue, file);
840         if (IS_ERR(bd))
841                 kref_put(&bcd->ref, bsg_kref_release_function);
842 
843         return bd;
844 }
845 
846 static int bsg_open(struct inode *inode, struct file *file)
847 {
848         struct bsg_device *bd;
849 
850         bd = bsg_get_device(inode, file);
851 
852         if (IS_ERR(bd))
853                 return PTR_ERR(bd);
854 
855         file->private_data = bd;
856         return 0;
857 }
858 
859 static int bsg_release(struct inode *inode, struct file *file)
860 {
861         struct bsg_device *bd = file->private_data;
862 
863         file->private_data = NULL;
864         return bsg_put_device(bd);
865 }
866 
867 static unsigned int bsg_poll(struct file *file, poll_table *wait)
868 {
869         struct bsg_device *bd = file->private_data;
870         unsigned int mask = 0;
871 
872         poll_wait(file, &bd->wq_done, wait);
873         poll_wait(file, &bd->wq_free, wait);
874 
875         spin_lock_irq(&bd->lock);
876         if (!list_empty(&bd->done_list))
877                 mask |= POLLIN | POLLRDNORM;
878         if (bd->queued_cmds < bd->max_queue)
879                 mask |= POLLOUT;
880         spin_unlock_irq(&bd->lock);
881 
882         return mask;
883 }
884 
885 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
886 {
887         struct bsg_device *bd = file->private_data;
888         int __user *uarg = (int __user *) arg;
889         int ret;
890 
891         switch (cmd) {
892                 /*
893                  * our own ioctls
894                  */
895         case SG_GET_COMMAND_Q:
896                 return put_user(bd->max_queue, uarg);
897         case SG_SET_COMMAND_Q: {
898                 int queue;
899 
900                 if (get_user(queue, uarg))
901                         return -EFAULT;
902                 if (queue < 1)
903                         return -EINVAL;
904 
905                 spin_lock_irq(&bd->lock);
906                 bd->max_queue = queue;
907                 spin_unlock_irq(&bd->lock);
908                 return 0;
909         }
910 
911         /*
912          * SCSI/sg ioctls
913          */
914         case SG_GET_VERSION_NUM:
915         case SCSI_IOCTL_GET_IDLUN:
916         case SCSI_IOCTL_GET_BUS_NUMBER:
917         case SG_SET_TIMEOUT:
918         case SG_GET_TIMEOUT:
919         case SG_GET_RESERVED_SIZE:
920         case SG_SET_RESERVED_SIZE:
921         case SG_EMULATED_HOST:
922         case SCSI_IOCTL_SEND_COMMAND: {
923                 void __user *uarg = (void __user *) arg;
924                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
925         }
926         case SG_IO: {
927                 struct request *rq;
928                 struct bio *bio, *bidi_bio = NULL;
929                 struct sg_io_v4 hdr;
930                 int at_head;
931                 u8 sense[SCSI_SENSE_BUFFERSIZE];
932 
933                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
934                         return -EFAULT;
935 
936                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
937                 if (IS_ERR(rq))
938                         return PTR_ERR(rq);
939 
940                 bio = rq->bio;
941                 if (rq->next_rq)
942                         bidi_bio = rq->next_rq->bio;
943 
944                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
945                 blk_execute_rq(bd->queue, NULL, rq, at_head);
946                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
947 
948                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
949                         return -EFAULT;
950 
951                 return ret;
952         }
953         /*
954          * block device ioctls
955          */
956         default:
957 #if 0
958                 return ioctl_by_bdev(bd->bdev, cmd, arg);
959 #else
960                 return -ENOTTY;
961 #endif
962         }
963 }
964 
965 static const struct file_operations bsg_fops = {
966         .read           =       bsg_read,
967         .write          =       bsg_write,
968         .poll           =       bsg_poll,
969         .open           =       bsg_open,
970         .release        =       bsg_release,
971         .unlocked_ioctl =       bsg_ioctl,
972         .owner          =       THIS_MODULE,
973         .llseek         =       default_llseek,
974 };
975 
976 void bsg_unregister_queue(struct request_queue *q)
977 {
978         struct bsg_class_device *bcd = &q->bsg_dev;
979 
980         if (!bcd->class_dev)
981                 return;
982 
983         mutex_lock(&bsg_mutex);
984         idr_remove(&bsg_minor_idr, bcd->minor);
985         if (q->kobj.sd)
986                 sysfs_remove_link(&q->kobj, "bsg");
987         device_unregister(bcd->class_dev);
988         bcd->class_dev = NULL;
989         kref_put(&bcd->ref, bsg_kref_release_function);
990         mutex_unlock(&bsg_mutex);
991 }
992 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
993 
994 int bsg_register_queue(struct request_queue *q, struct device *parent,
995                        const char *name, void (*release)(struct device *))
996 {
997         struct bsg_class_device *bcd;
998         dev_t dev;
999         int ret;
1000         struct device *class_dev = NULL;
1001         const char *devname;
1002 
1003         if (name)
1004                 devname = name;
1005         else
1006                 devname = dev_name(parent);
1007 
1008         /*
1009          * we need a proper transport to send commands, not a stacked device
1010          */
1011         if (!q->request_fn)
1012                 return 0;
1013 
1014         bcd = &q->bsg_dev;
1015         memset(bcd, 0, sizeof(*bcd));
1016 
1017         mutex_lock(&bsg_mutex);
1018 
1019         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
1020         if (ret < 0) {
1021                 if (ret == -ENOSPC) {
1022                         printk(KERN_ERR "bsg: too many bsg devices\n");
1023                         ret = -EINVAL;
1024                 }
1025                 goto unlock;
1026         }
1027 
1028         bcd->minor = ret;
1029         bcd->queue = q;
1030         bcd->parent = get_device(parent);
1031         bcd->release = release;
1032         kref_init(&bcd->ref);
1033         dev = MKDEV(bsg_major, bcd->minor);
1034         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1035         if (IS_ERR(class_dev)) {
1036                 ret = PTR_ERR(class_dev);
1037                 goto put_dev;
1038         }
1039         bcd->class_dev = class_dev;
1040 
1041         if (q->kobj.sd) {
1042                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1043                 if (ret)
1044                         goto unregister_class_dev;
1045         }
1046 
1047         mutex_unlock(&bsg_mutex);
1048         return 0;
1049 
1050 unregister_class_dev:
1051         device_unregister(class_dev);
1052 put_dev:
1053         put_device(parent);
1054         idr_remove(&bsg_minor_idr, bcd->minor);
1055 unlock:
1056         mutex_unlock(&bsg_mutex);
1057         return ret;
1058 }
1059 EXPORT_SYMBOL_GPL(bsg_register_queue);
1060 
1061 static struct cdev bsg_cdev;
1062 
1063 static char *bsg_devnode(struct device *dev, umode_t *mode)
1064 {
1065         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1066 }
1067 
1068 static int __init bsg_init(void)
1069 {
1070         int ret, i;
1071         dev_t devid;
1072 
1073         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1074                                 sizeof(struct bsg_command), 0, 0, NULL);
1075         if (!bsg_cmd_cachep) {
1076                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1077                 return -ENOMEM;
1078         }
1079 
1080         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1081                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1082 
1083         bsg_class = class_create(THIS_MODULE, "bsg");
1084         if (IS_ERR(bsg_class)) {
1085                 ret = PTR_ERR(bsg_class);
1086                 goto destroy_kmemcache;
1087         }
1088         bsg_class->devnode = bsg_devnode;
1089 
1090         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1091         if (ret)
1092                 goto destroy_bsg_class;
1093 
1094         bsg_major = MAJOR(devid);
1095 
1096         cdev_init(&bsg_cdev, &bsg_fops);
1097         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1098         if (ret)
1099                 goto unregister_chrdev;
1100 
1101         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1102                " loaded (major %d)\n", bsg_major);
1103         return 0;
1104 unregister_chrdev:
1105         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1106 destroy_bsg_class:
1107         class_destroy(bsg_class);
1108 destroy_kmemcache:
1109         kmem_cache_destroy(bsg_cmd_cachep);
1110         return ret;
1111 }
1112 
1113 MODULE_AUTHOR("Jens Axboe");
1114 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1115 MODULE_LICENSE("GPL");
1116 
1117 device_initcall(bsg_init);
1118 

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