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Subject[v2.6.34-stable 121/165] [SCSI] Make scsi_free_queue() kill pending SCSI commands
Date
From: Bart Van Assche <bvanassche@acm.org>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit 3308511c93e6ad0d3c58984ecd6e5e57f96b12c8 upstream.

Make sure that SCSI device removal via scsi_remove_host() does finish
all pending SCSI commands. Currently that's not the case and hence
removal of a SCSI host during I/O can cause a deadlock. See also
"blkdev_issue_discard() hangs forever if underlying storage device is
removed" (http://bugzilla.kernel.org/show_bug.cgi?id=40472). See also
http://lkml.org/lkml/2011/8/27/6.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/scsi/hosts.c | 9 ++++++---
drivers/scsi/scsi_lib.c | 9 +++++++++
2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 6660fa9..cdd904d 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -280,6 +280,7 @@ static void scsi_host_dev_release(struct device *dev)
{
struct Scsi_Host *shost = dev_to_shost(dev);
struct device *parent = dev->parent;
+ struct request_queue *q;

scsi_proc_hostdir_rm(shost->hostt);

@@ -287,9 +288,11 @@ static void scsi_host_dev_release(struct device *dev)
kthread_stop(shost->ehandler);
if (shost->work_q)
destroy_workqueue(shost->work_q);
- if (shost->uspace_req_q) {
- kfree(shost->uspace_req_q->queuedata);
- scsi_free_queue(shost->uspace_req_q);
+ q = shost->uspace_req_q;
+ if (q) {
+ kfree(q->queuedata);
+ q->queuedata = NULL;
+ scsi_free_queue(q);
}

scsi_destroy_command_freelist(shost);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 725f3cd..9f240f4 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1676,6 +1676,15 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)

void scsi_free_queue(struct request_queue *q)
{
+ unsigned long flags;
+
+ WARN_ON(q->queuedata);
+
+ /* cause scsi_request_fn() to kill all non-finished requests */
+ spin_lock_irqsave(q->queue_lock, flags);
+ q->request_fn(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
blk_cleanup_queue(q);
}

--
1.7.12.rc2


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