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authorJames Bottomley <James.Bottomley@steeleye.com>2006-09-05 17:26:41 -0400
committerJames Bottomley <jejb@mulgrave.il.steeleye.com>2006-09-07 11:08:43 -0400
commit884d25cc4fda20908fd4ef93dbb41d817984b68b (patch)
tree99a7a2a02ff76bee9c4a0620e6a90321517bba13 /drivers/scsi/scsi_scan.c
parent26dacd0c9b2dc1dc987c376aeee4e80691a7dd0b (diff)
[SCSI] Fix refcount breakage with 'echo "1" > scan' when target already present
Spotted by: Dan Aloni <da-xx@monatomic.org> The problem is there's inconsistent locking semantic usage of scsi_alloc_target(). Two callers assume the target comes back with reference unincremented and the third assumes its incremented. Fix by always making the reference incremented on return. Also fix path in target alloc that could consistently increment the parent lock. Finally document scsi_alloc_target() so its callers know what the expectations are. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Diffstat (limited to 'drivers/scsi/scsi_scan.c')
-rw-r--r--drivers/scsi/scsi_scan.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 31d05ab0b2fc..fd9e281c3bfe 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -266,6 +266,18 @@ static struct scsi_target *__scsi_find_target(struct device *parent,
266 return found_starget; 266 return found_starget;
267} 267}
268 268
269/**
270 * scsi_alloc_target - allocate a new or find an existing target
271 * @parent: parent of the target (need not be a scsi host)
272 * @channel: target channel number (zero if no channels)
273 * @id: target id number
274 *
275 * Return an existing target if one exists, provided it hasn't already
276 * gone into STARGET_DEL state, otherwise allocate a new target.
277 *
278 * The target is returned with an incremented reference, so the caller
279 * is responsible for both reaping and doing a last put
280 */
269static struct scsi_target *scsi_alloc_target(struct device *parent, 281static struct scsi_target *scsi_alloc_target(struct device *parent,
270 int channel, uint id) 282 int channel, uint id)
271{ 283{
@@ -331,14 +343,15 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
331 return NULL; 343 return NULL;
332 } 344 }
333 } 345 }
346 get_device(dev);
334 347
335 return starget; 348 return starget;
336 349
337 found: 350 found:
338 found_target->reap_ref++; 351 found_target->reap_ref++;
339 spin_unlock_irqrestore(shost->host_lock, flags); 352 spin_unlock_irqrestore(shost->host_lock, flags);
340 put_device(parent);
341 if (found_target->state != STARGET_DEL) { 353 if (found_target->state != STARGET_DEL) {
354 put_device(parent);
342 kfree(starget); 355 kfree(starget);
343 return found_target; 356 return found_target;
344 } 357 }
@@ -1341,7 +1354,6 @@ struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
1341 if (!starget) 1354 if (!starget)
1342 return ERR_PTR(-ENOMEM); 1355 return ERR_PTR(-ENOMEM);
1343 1356
1344 get_device(&starget->dev);
1345 mutex_lock(&shost->scan_mutex); 1357 mutex_lock(&shost->scan_mutex);
1346 if (scsi_host_scan_allowed(shost)) 1358 if (scsi_host_scan_allowed(shost))
1347 scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata); 1359 scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
@@ -1400,7 +1412,6 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel,
1400 if (!starget) 1412 if (!starget)
1401 return; 1413 return;
1402 1414
1403 get_device(&starget->dev);
1404 if (lun != SCAN_WILD_CARD) { 1415 if (lun != SCAN_WILD_CARD) {
1405 /* 1416 /*
1406 * Scan for a specific host/chan/id/lun. 1417 * Scan for a specific host/chan/id/lun.
@@ -1582,7 +1593,8 @@ struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
1582 if (sdev) { 1593 if (sdev) {
1583 sdev->sdev_gendev.parent = get_device(&starget->dev); 1594 sdev->sdev_gendev.parent = get_device(&starget->dev);
1584 sdev->borken = 0; 1595 sdev->borken = 0;
1585 } 1596 } else
1597 scsi_target_reap(starget);
1586 put_device(&starget->dev); 1598 put_device(&starget->dev);
1587 out: 1599 out:
1588 mutex_unlock(&shost->scan_mutex); 1600 mutex_unlock(&shost->scan_mutex);