This is a note to let you know that I've just added the patch titled
SCSI: scsi_remove_target: fix softlockup regression on hot remove
to the 3.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
scsi-scsi_remove_target-fix-softlockup-regression-on-hot-remove.patch
and it can be found in the queue-3.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From bc3f02a795d3b4faa99d37390174be2a75d091bd Mon Sep 17 00:00:00 2001
From: Dan Williams <[email protected]>
Date: Tue, 28 Aug 2012 22:12:10 -0700
Subject: SCSI: scsi_remove_target: fix softlockup regression on hot remove
From: Dan Williams <[email protected]>
commit bc3f02a795d3b4faa99d37390174be2a75d091bd upstream.
John reports:
BUG: soft lockup - CPU#2 stuck for 23s! [kworker/u:8:2202]
[..]
Call Trace:
[<ffffffff8141782a>] scsi_remove_target+0xda/0x1f0
[<ffffffff81421de5>] sas_rphy_remove+0x55/0x60
[<ffffffff81421e01>] sas_rphy_delete+0x11/0x20
[<ffffffff81421e35>] sas_port_delete+0x25/0x160
[<ffffffff814549a3>] mptsas_del_end_device+0x183/0x270
...introduced by commit 3b661a9 "[SCSI] fix hot unplug vs async scan race".
Don't restart lookup of more stargets in the multi-target case, just
arrange to traverse the list once, on the assumption that new targets
are always added at the end. There is no guarantee that the target will
change state in scsi_target_reap() so we can end up spinning if we
restart.
Acked-by: Jack Wang <[email protected]>
LKML-Reference:
<CAEhu1-6wq1YsNiscGMwP4ud0Q+MrViRzv=kcwcqsbnc8c68...@mail.gmail.com>
Reported-by: John Drescher <[email protected]>
Tested-by: John Drescher <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/scsi/scsi_sysfs.c | 30 ++++++++++++++----------------
1 file changed, 14 insertions(+), 16 deletions(-)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1023,33 +1023,31 @@ static void __scsi_remove_target(struct
void scsi_remove_target(struct device *dev)
{
struct Scsi_Host *shost = dev_to_shost(dev->parent);
- struct scsi_target *starget, *found;
+ struct scsi_target *starget, *last = NULL;
unsigned long flags;
- restart:
- found = NULL;
+ /* remove targets being careful to lookup next entry before
+ * deleting the last
+ */
spin_lock_irqsave(shost->host_lock, flags);
list_for_each_entry(starget, &shost->__targets, siblings) {
if (starget->state == STARGET_DEL)
continue;
if (starget->dev.parent == dev || &starget->dev == dev) {
- found = starget;
- found->reap_ref++;
- break;
+ /* assuming new targets arrive at the end */
+ starget->reap_ref++;
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ if (last)
+ scsi_target_reap(last);
+ last = starget;
+ __scsi_remove_target(starget);
+ spin_lock_irqsave(shost->host_lock, flags);
}
}
spin_unlock_irqrestore(shost->host_lock, flags);
- if (found) {
- __scsi_remove_target(found);
- scsi_target_reap(found);
- /* in the case where @dev has multiple starget children,
- * continue removing.
- *
- * FIXME: does such a case exist?
- */
- goto restart;
- }
+ if (last)
+ scsi_target_reap(last);
}
EXPORT_SYMBOL(scsi_remove_target);
Patches currently in stable-queue which might be from [email protected] are
queue-3.5/scsi-scsi_remove_target-fix-softlockup-regression-on-hot-remove.patch
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