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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 
200         rq->timeout = msecs_to_jiffies(hdr->timeout);
201         if (!rq->timeout)
202                 rq->timeout = q->sg_timeout;
203         if (!rq->timeout)
204                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
205         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
206                 rq->timeout = BLK_MIN_SG_TIMEOUT;
207 
208         return 0;
209 }
210 
211 /*
212  * Check if sg_io_v4 from user is allowed and valid
213  */
214 static int
215 bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
216 {
217         int ret = 0;
218 
219         if (hdr->guard != 'Q')
220                 return -EINVAL;
221 
222         switch (hdr->protocol) {
223         case BSG_PROTOCOL_SCSI:
224                 switch (hdr->subprotocol) {
225                 case BSG_SUB_PROTOCOL_SCSI_CMD:
226                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
227                         break;
228                 default:
229                         ret = -EINVAL;
230                 }
231                 break;
232         default:
233                 ret = -EINVAL;
234         }
235 
236         *rw = hdr->dout_xfer_len ? WRITE : READ;
237         return ret;
238 }
239 
240 /*
241  * map sg_io_v4 to a request.
242  */
243 static struct request *
244 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
245             u8 *sense)
246 {
247         struct request_queue *q = bd->queue;
248         struct request *rq, *next_rq = NULL;
249         int ret, rw;
250         unsigned int dxfer_len;
251         void __user *dxferp = NULL;
252         struct bsg_class_device *bcd = &q->bsg_dev;
253 
254         /* if the LLD has been removed then the bsg_unregister_queue will
255          * eventually be called and the class_dev was freed, so we can no
256          * longer use this request_queue. Return no such address.
257          */
258         if (!bcd->class_dev)
259                 return ERR_PTR(-ENXIO);
260 
261         dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
262                 hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
263                 hdr->din_xfer_len);
264 
265         ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
266         if (ret)
267                 return ERR_PTR(ret);
268 
269         /*
270          * map scatter-gather elements separately and string them to request
271          */
272         rq = blk_get_request(q, rw, GFP_KERNEL);
273         if (!rq)
274                 return ERR_PTR(-ENOMEM);
275         blk_rq_set_block_pc(rq);
276 
277         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
278         if (ret)
279                 goto out;
280 
281         if (rw == WRITE && hdr->din_xfer_len) {
282                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
283                         ret = -EOPNOTSUPP;
284                         goto out;
285                 }
286 
287                 next_rq = blk_get_request(q, READ, GFP_KERNEL);
288                 if (!next_rq) {
289                         ret = -ENOMEM;
290                         goto out;
291                 }
292                 rq->next_rq = next_rq;
293                 next_rq->cmd_type = rq->cmd_type;
294 
295                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
296                 ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
297                                        hdr->din_xfer_len, GFP_KERNEL);
298                 if (ret)
299                         goto out;
300         }
301 
302         if (hdr->dout_xfer_len) {
303                 dxfer_len = hdr->dout_xfer_len;
304                 dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
305         } else if (hdr->din_xfer_len) {
306                 dxfer_len = hdr->din_xfer_len;
307                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
308         } else
309                 dxfer_len = 0;
310 
311         if (dxfer_len) {
312                 ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
313                                       GFP_KERNEL);
314                 if (ret)
315                         goto out;
316         }
317 
318         rq->sense = sense;
319         rq->sense_len = 0;
320 
321         return rq;
322 out:
323         if (rq->cmd != rq->__cmd)
324                 kfree(rq->cmd);
325         blk_put_request(rq);
326         if (next_rq) {
327                 blk_rq_unmap_user(next_rq->bio);
328                 blk_put_request(next_rq);
329         }
330         return ERR_PTR(ret);
331 }
332 
333 /*
334  * async completion call-back from the block layer, when scsi/ide/whatever
335  * calls end_that_request_last() on a request
336  */
337 static void bsg_rq_end_io(struct request *rq, int uptodate)
338 {
339         struct bsg_command *bc = rq->end_io_data;
340         struct bsg_device *bd = bc->bd;
341         unsigned long flags;
342 
343         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
344                 bd->name, rq, bc, bc->bio, uptodate);
345 
346         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
347 
348         spin_lock_irqsave(&bd->lock, flags);
349         list_move_tail(&bc->list, &bd->done_list);
350         bd->done_cmds++;
351         spin_unlock_irqrestore(&bd->lock, flags);
352 
353         wake_up(&bd->wq_done);
354 }
355 
356 /*
357  * do final setup of a 'bc' and submit the matching 'rq' to the block
358  * layer for io
359  */
360 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
361                             struct bsg_command *bc, struct request *rq)
362 {
363         int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
364 
365         /*
366          * add bc command to busy queue and submit rq for io
367          */
368         bc->rq = rq;
369         bc->bio = rq->bio;
370         if (rq->next_rq)
371                 bc->bidi_bio = rq->next_rq->bio;
372         bc->hdr.duration = jiffies;
373         spin_lock_irq(&bd->lock);
374         list_add_tail(&bc->list, &bd->busy_list);
375         spin_unlock_irq(&bd->lock);
376 
377         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
378 
379         rq->end_io_data = bc;
380         blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
381 }
382 
383 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
384 {
385         struct bsg_command *bc = NULL;
386 
387         spin_lock_irq(&bd->lock);
388         if (bd->done_cmds) {
389                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
390                 list_del(&bc->list);
391                 bd->done_cmds--;
392         }
393         spin_unlock_irq(&bd->lock);
394 
395         return bc;
396 }
397 
398 /*
399  * Get a finished command from the done list
400  */
401 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
402 {
403         struct bsg_command *bc;
404         int ret;
405 
406         do {
407                 bc = bsg_next_done_cmd(bd);
408                 if (bc)
409                         break;
410 
411                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
412                         bc = ERR_PTR(-EAGAIN);
413                         break;
414                 }
415 
416                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
417                 if (ret) {
418                         bc = ERR_PTR(-ERESTARTSYS);
419                         break;
420                 }
421         } while (1);
422 
423         dprintk("%s: returning done %p\n", bd->name, bc);
424 
425         return bc;
426 }
427 
428 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
429                                     struct bio *bio, struct bio *bidi_bio)
430 {
431         int ret = 0;
432 
433         dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
434         /*
435          * fill in all the output members
436          */
437         hdr->device_status = rq->errors & 0xff;
438         hdr->transport_status = host_byte(rq->errors);
439         hdr->driver_status = driver_byte(rq->errors);
440         hdr->info = 0;
441         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
442                 hdr->info |= SG_INFO_CHECK;
443         hdr->response_len = 0;
444 
445         if (rq->sense_len && hdr->response) {
446                 int len = min_t(unsigned int, hdr->max_response_len,
447                                         rq->sense_len);
448 
449                 ret = copy_to_user((void __user *)(unsigned long)hdr->response,
450                                    rq->sense, len);
451                 if (!ret)
452                         hdr->response_len = len;
453                 else
454                         ret = -EFAULT;
455         }
456 
457         if (rq->next_rq) {
458                 hdr->dout_resid = rq->resid_len;
459                 hdr->din_resid = rq->next_rq->resid_len;
460                 blk_rq_unmap_user(bidi_bio);
461                 blk_put_request(rq->next_rq);
462         } else if (rq_data_dir(rq) == READ)
463                 hdr->din_resid = rq->resid_len;
464         else
465                 hdr->dout_resid = rq->resid_len;
466 
467         /*
468          * If the request generated a negative error number, return it
469          * (providing we aren't already returning an error); if it's
470          * just a protocol response (i.e. non negative), that gets
471          * processed above.
472          */
473         if (!ret && rq->errors < 0)
474                 ret = rq->errors;
475 
476         blk_rq_unmap_user(bio);
477         if (rq->cmd != rq->__cmd)
478                 kfree(rq->cmd);
479         blk_put_request(rq);
480 
481         return ret;
482 }
483 
484 static int bsg_complete_all_commands(struct bsg_device *bd)
485 {
486         struct bsg_command *bc;
487         int ret, tret;
488 
489         dprintk("%s: entered\n", bd->name);
490 
491         /*
492          * wait for all commands to complete
493          */
494         ret = 0;
495         do {
496                 ret = bsg_io_schedule(bd);
497                 /*
498                  * look for -ENODATA specifically -- we'll sometimes get
499                  * -ERESTARTSYS when we've taken a signal, but we can't
500                  * return until we're done freeing the queue, so ignore
501                  * it.  The signal will get handled when we're done freeing
502                  * the bsg_device.
503                  */
504         } while (ret != -ENODATA);
505 
506         /*
507          * discard done commands
508          */
509         ret = 0;
510         do {
511                 spin_lock_irq(&bd->lock);
512                 if (!bd->queued_cmds) {
513                         spin_unlock_irq(&bd->lock);
514                         break;
515                 }
516                 spin_unlock_irq(&bd->lock);
517 
518                 bc = bsg_get_done_cmd(bd);
519                 if (IS_ERR(bc))
520                         break;
521 
522                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
523                                                 bc->bidi_bio);
524                 if (!ret)
525                         ret = tret;
526 
527                 bsg_free_command(bc);
528         } while (1);
529 
530         return ret;
531 }
532 
533 static int
534 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
535            const struct iovec *iov, ssize_t *bytes_read)
536 {
537         struct bsg_command *bc;
538         int nr_commands, ret;
539 
540         if (count % sizeof(struct sg_io_v4))
541                 return -EINVAL;
542 
543         ret = 0;
544         nr_commands = count / sizeof(struct sg_io_v4);
545         while (nr_commands) {
546                 bc = bsg_get_done_cmd(bd);
547                 if (IS_ERR(bc)) {
548                         ret = PTR_ERR(bc);
549                         break;
550                 }
551 
552                 /*
553                  * this is the only case where we need to copy data back
554                  * after completing the request. so do that here,
555                  * bsg_complete_work() cannot do that for us
556                  */
557                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
558                                                bc->bidi_bio);
559 
560                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
561                         ret = -EFAULT;
562 
563                 bsg_free_command(bc);
564 
565                 if (ret)
566                         break;
567 
568                 buf += sizeof(struct sg_io_v4);
569                 *bytes_read += sizeof(struct sg_io_v4);
570                 nr_commands--;
571         }
572 
573         return ret;
574 }
575 
576 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
577 {
578         if (file->f_flags & O_NONBLOCK)
579                 clear_bit(BSG_F_BLOCK, &bd->flags);
580         else
581                 set_bit(BSG_F_BLOCK, &bd->flags);
582 }
583 
584 /*
585  * Check if the error is a "real" error that we should return.
586  */
587 static inline int err_block_err(int ret)
588 {
589         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
590                 return 1;
591 
592         return 0;
593 }
594 
595 static ssize_t
596 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
597 {
598         struct bsg_device *bd = file->private_data;
599         int ret;
600         ssize_t bytes_read;
601 
602         dprintk("%s: read %Zd bytes\n", bd->name, count);
603 
604         bsg_set_block(bd, file);
605 
606         bytes_read = 0;
607         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
608         *ppos = bytes_read;
609 
610         if (!bytes_read || err_block_err(ret))
611                 bytes_read = ret;
612 
613         return bytes_read;
614 }
615 
616 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
617                        size_t count, ssize_t *bytes_written,
618                        fmode_t has_write_perm)
619 {
620         struct bsg_command *bc;
621         struct request *rq;
622         int ret, nr_commands;
623 
624         if (count % sizeof(struct sg_io_v4))
625                 return -EINVAL;
626 
627         nr_commands = count / sizeof(struct sg_io_v4);
628         rq = NULL;
629         bc = NULL;
630         ret = 0;
631         while (nr_commands) {
632                 struct request_queue *q = bd->queue;
633 
634                 bc = bsg_alloc_command(bd);
635                 if (IS_ERR(bc)) {
636                         ret = PTR_ERR(bc);
637                         bc = NULL;
638                         break;
639                 }
640 
641                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
642                         ret = -EFAULT;
643                         break;
644                 }
645 
646                 /*
647                  * get a request, fill in the blanks, and add to request queue
648                  */
649                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
650                 if (IS_ERR(rq)) {
651                         ret = PTR_ERR(rq);
652                         rq = NULL;
653                         break;
654                 }
655 
656                 bsg_add_command(bd, q, bc, rq);
657                 bc = NULL;
658                 rq = NULL;
659                 nr_commands--;
660                 buf += sizeof(struct sg_io_v4);
661                 *bytes_written += sizeof(struct sg_io_v4);
662         }
663 
664         if (bc)
665                 bsg_free_command(bc);
666 
667         return ret;
668 }
669 
670 static ssize_t
671 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
672 {
673         struct bsg_device *bd = file->private_data;
674         ssize_t bytes_written;
675         int ret;
676 
677         dprintk("%s: write %Zd bytes\n", bd->name, count);
678 
679         if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
680                 return -EINVAL;
681 
682         bsg_set_block(bd, file);
683 
684         bytes_written = 0;
685         ret = __bsg_write(bd, buf, count, &bytes_written,
686                           file->f_mode & FMODE_WRITE);
687 
688         *ppos = bytes_written;
689 
690         /*
691          * return bytes written on non-fatal errors
692          */
693         if (!bytes_written || err_block_err(ret))
694                 bytes_written = ret;
695 
696         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
697         return bytes_written;
698 }
699 
700 static struct bsg_device *bsg_alloc_device(void)
701 {
702         struct bsg_device *bd;
703 
704         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
705         if (unlikely(!bd))
706                 return NULL;
707 
708         spin_lock_init(&bd->lock);
709 
710         bd->max_queue = BSG_DEFAULT_CMDS;
711 
712         INIT_LIST_HEAD(&bd->busy_list);
713         INIT_LIST_HEAD(&bd->done_list);
714         INIT_HLIST_NODE(&bd->dev_list);
715 
716         init_waitqueue_head(&bd->wq_free);
717         init_waitqueue_head(&bd->wq_done);
718         return bd;
719 }
720 
721 static void bsg_kref_release_function(struct kref *kref)
722 {
723         struct bsg_class_device *bcd =
724                 container_of(kref, struct bsg_class_device, ref);
725         struct device *parent = bcd->parent;
726 
727         if (bcd->release)
728                 bcd->release(bcd->parent);
729 
730         put_device(parent);
731 }
732 
733 static int bsg_put_device(struct bsg_device *bd)
734 {
735         int ret = 0, do_free;
736         struct request_queue *q = bd->queue;
737 
738         mutex_lock(&bsg_mutex);
739 
740         do_free = atomic_dec_and_test(&bd->ref_count);
741         if (!do_free) {
742                 mutex_unlock(&bsg_mutex);
743                 goto out;
744         }
745 
746         hlist_del(&bd->dev_list);
747         mutex_unlock(&bsg_mutex);
748 
749         dprintk("%s: tearing down\n", bd->name);
750 
751         /*
752          * close can always block
753          */
754         set_bit(BSG_F_BLOCK, &bd->flags);
755 
756         /*
757          * correct error detection baddies here again. it's the responsibility
758          * of the app to properly reap commands before close() if it wants
759          * fool-proof error detection
760          */
761         ret = bsg_complete_all_commands(bd);
762 
763         kfree(bd);
764 out:
765         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
766         if (do_free)
767                 blk_put_queue(q);
768         return ret;
769 }
770 
771 static struct bsg_device *bsg_add_device(struct inode *inode,
772                                          struct request_queue *rq,
773                                          struct file *file)
774 {
775         struct bsg_device *bd;
776 #ifdef BSG_DEBUG
777         unsigned char buf[32];
778 #endif
779         if (!blk_get_queue(rq))
780                 return ERR_PTR(-ENXIO);
781 
782         bd = bsg_alloc_device();
783         if (!bd) {
784                 blk_put_queue(rq);
785                 return ERR_PTR(-ENOMEM);
786         }
787 
788         bd->queue = rq;
789 
790         bsg_set_block(bd, file);
791 
792         atomic_set(&bd->ref_count, 1);
793         mutex_lock(&bsg_mutex);
794         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
795 
796         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
797         dprintk("bound to <%s>, max queue %d\n",
798                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
799 
800         mutex_unlock(&bsg_mutex);
801         return bd;
802 }
803 
804 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
805 {
806         struct bsg_device *bd;
807 
808         mutex_lock(&bsg_mutex);
809 
810         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
811                 if (bd->queue == q) {
812                         atomic_inc(&bd->ref_count);
813                         goto found;
814                 }
815         }
816         bd = NULL;
817 found:
818         mutex_unlock(&bsg_mutex);
819         return bd;
820 }
821 
822 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
823 {
824         struct bsg_device *bd;
825         struct bsg_class_device *bcd;
826 
827         /*
828          * find the class device
829          */
830         mutex_lock(&bsg_mutex);
831         bcd = idr_find(&bsg_minor_idr, iminor(inode));
832         if (bcd)
833                 kref_get(&bcd->ref);
834         mutex_unlock(&bsg_mutex);
835 
836         if (!bcd)
837                 return ERR_PTR(-ENODEV);
838 
839         bd = __bsg_get_device(iminor(inode), bcd->queue);
840         if (bd)
841                 return bd;
842 
843         bd = bsg_add_device(inode, bcd->queue, file);
844         if (IS_ERR(bd))
845                 kref_put(&bcd->ref, bsg_kref_release_function);
846 
847         return bd;
848 }
849 
850 static int bsg_open(struct inode *inode, struct file *file)
851 {
852         struct bsg_device *bd;
853 
854         bd = bsg_get_device(inode, file);
855 
856         if (IS_ERR(bd))
857                 return PTR_ERR(bd);
858 
859         file->private_data = bd;
860         return 0;
861 }
862 
863 static int bsg_release(struct inode *inode, struct file *file)
864 {
865         struct bsg_device *bd = file->private_data;
866 
867         file->private_data = NULL;
868         return bsg_put_device(bd);
869 }
870 
871 static unsigned int bsg_poll(struct file *file, poll_table *wait)
872 {
873         struct bsg_device *bd = file->private_data;
874         unsigned int mask = 0;
875 
876         poll_wait(file, &bd->wq_done, wait);
877         poll_wait(file, &bd->wq_free, wait);
878 
879         spin_lock_irq(&bd->lock);
880         if (!list_empty(&bd->done_list))
881                 mask |= POLLIN | POLLRDNORM;
882         if (bd->queued_cmds < bd->max_queue)
883                 mask |= POLLOUT;
884         spin_unlock_irq(&bd->lock);
885 
886         return mask;
887 }
888 
889 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
890 {
891         struct bsg_device *bd = file->private_data;
892         int __user *uarg = (int __user *) arg;
893         int ret;
894 
895         switch (cmd) {
896                 /*
897                  * our own ioctls
898                  */
899         case SG_GET_COMMAND_Q:
900                 return put_user(bd->max_queue, uarg);
901         case SG_SET_COMMAND_Q: {
902                 int queue;
903 
904                 if (get_user(queue, uarg))
905                         return -EFAULT;
906                 if (queue < 1)
907                         return -EINVAL;
908 
909                 spin_lock_irq(&bd->lock);
910                 bd->max_queue = queue;
911                 spin_unlock_irq(&bd->lock);
912                 return 0;
913         }
914 
915         /*
916          * SCSI/sg ioctls
917          */
918         case SG_GET_VERSION_NUM:
919         case SCSI_IOCTL_GET_IDLUN:
920         case SCSI_IOCTL_GET_BUS_NUMBER:
921         case SG_SET_TIMEOUT:
922         case SG_GET_TIMEOUT:
923         case SG_GET_RESERVED_SIZE:
924         case SG_SET_RESERVED_SIZE:
925         case SG_EMULATED_HOST:
926         case SCSI_IOCTL_SEND_COMMAND: {
927                 void __user *uarg = (void __user *) arg;
928                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
929         }
930         case SG_IO: {
931                 struct request *rq;
932                 struct bio *bio, *bidi_bio = NULL;
933                 struct sg_io_v4 hdr;
934                 int at_head;
935                 u8 sense[SCSI_SENSE_BUFFERSIZE];
936 
937                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
938                         return -EFAULT;
939 
940                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
941                 if (IS_ERR(rq))
942                         return PTR_ERR(rq);
943 
944                 bio = rq->bio;
945                 if (rq->next_rq)
946                         bidi_bio = rq->next_rq->bio;
947 
948                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
949                 blk_execute_rq(bd->queue, NULL, rq, at_head);
950                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
951 
952                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
953                         return -EFAULT;
954 
955                 return ret;
956         }
957         /*
958          * block device ioctls
959          */
960         default:
961 #if 0
962                 return ioctl_by_bdev(bd->bdev, cmd, arg);
963 #else
964                 return -ENOTTY;
965 #endif
966         }
967 }
968 
969 static const struct file_operations bsg_fops = {
970         .read           =       bsg_read,
971         .write          =       bsg_write,
972         .poll           =       bsg_poll,
973         .open           =       bsg_open,
974         .release        =       bsg_release,
975         .unlocked_ioctl =       bsg_ioctl,
976         .owner          =       THIS_MODULE,
977         .llseek         =       default_llseek,
978 };
979 
980 void bsg_unregister_queue(struct request_queue *q)
981 {
982         struct bsg_class_device *bcd = &q->bsg_dev;
983 
984         if (!bcd->class_dev)
985                 return;
986 
987         mutex_lock(&bsg_mutex);
988         idr_remove(&bsg_minor_idr, bcd->minor);
989         if (q->kobj.sd)
990                 sysfs_remove_link(&q->kobj, "bsg");
991         device_unregister(bcd->class_dev);
992         bcd->class_dev = NULL;
993         kref_put(&bcd->ref, bsg_kref_release_function);
994         mutex_unlock(&bsg_mutex);
995 }
996 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
997 
998 int bsg_register_queue(struct request_queue *q, struct device *parent,
999                        const char *name, void (*release)(struct device *))
1000 {
1001         struct bsg_class_device *bcd;
1002         dev_t dev;
1003         int ret;
1004         struct device *class_dev = NULL;
1005         const char *devname;
1006 
1007         if (name)
1008                 devname = name;
1009         else
1010                 devname = dev_name(parent);
1011 
1012         /*
1013          * we need a proper transport to send commands, not a stacked device
1014          */
1015         if (!queue_is_rq_based(q))
1016                 return 0;
1017 
1018         bcd = &q->bsg_dev;
1019         memset(bcd, 0, sizeof(*bcd));
1020 
1021         mutex_lock(&bsg_mutex);
1022 
1023         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
1024         if (ret < 0) {
1025                 if (ret == -ENOSPC) {
1026                         printk(KERN_ERR "bsg: too many bsg devices\n");
1027                         ret = -EINVAL;
1028                 }
1029                 goto unlock;
1030         }
1031 
1032         bcd->minor = ret;
1033         bcd->queue = q;
1034         bcd->parent = get_device(parent);
1035         bcd->release = release;
1036         kref_init(&bcd->ref);
1037         dev = MKDEV(bsg_major, bcd->minor);
1038         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1039         if (IS_ERR(class_dev)) {
1040                 ret = PTR_ERR(class_dev);
1041                 goto put_dev;
1042         }
1043         bcd->class_dev = class_dev;
1044 
1045         if (q->kobj.sd) {
1046                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1047                 if (ret)
1048                         goto unregister_class_dev;
1049         }
1050 
1051         mutex_unlock(&bsg_mutex);
1052         return 0;
1053 
1054 unregister_class_dev:
1055         device_unregister(class_dev);
1056 put_dev:
1057         put_device(parent);
1058         idr_remove(&bsg_minor_idr, bcd->minor);
1059 unlock:
1060         mutex_unlock(&bsg_mutex);
1061         return ret;
1062 }
1063 EXPORT_SYMBOL_GPL(bsg_register_queue);
1064 
1065 static struct cdev bsg_cdev;
1066 
1067 static char *bsg_devnode(struct device *dev, umode_t *mode)
1068 {
1069         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1070 }
1071 
1072 static int __init bsg_init(void)
1073 {
1074         int ret, i;
1075         dev_t devid;
1076 
1077         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1078                                 sizeof(struct bsg_command), 0, 0, NULL);
1079         if (!bsg_cmd_cachep) {
1080                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1081                 return -ENOMEM;
1082         }
1083 
1084         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1085                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1086 
1087         bsg_class = class_create(THIS_MODULE, "bsg");
1088         if (IS_ERR(bsg_class)) {
1089                 ret = PTR_ERR(bsg_class);
1090                 goto destroy_kmemcache;
1091         }
1092         bsg_class->devnode = bsg_devnode;
1093 
1094         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1095         if (ret)
1096                 goto destroy_bsg_class;
1097 
1098         bsg_major = MAJOR(devid);
1099 
1100         cdev_init(&bsg_cdev, &bsg_fops);
1101         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1102         if (ret)
1103                 goto unregister_chrdev;
1104 
1105         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1106                " loaded (major %d)\n", bsg_major);
1107         return 0;
1108 unregister_chrdev:
1109         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1110 destroy_bsg_class:
1111         class_destroy(bsg_class);
1112 destroy_kmemcache:
1113         kmem_cache_destroy(bsg_cmd_cachep);
1114         return ret;
1115 }
1116 
1117 MODULE_AUTHOR("Jens Axboe");
1118 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1119 MODULE_LICENSE("GPL");
1120 
1121 device_initcall(bsg_init);
1122 

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