Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorDan Williams <djbw@fb.com>2012-08-28 22:12:10 -0700
committerJames Bottomley <JBottomley@Parallels.com>2012-09-24 12:17:49 +0400
commitbc3f02a795d3b4faa99d37390174be2a75d091bd (patch)
treeb1a5b23444144338e4c1937029f55940f82c638d
parent225c56960fcafeccc2b6304f96cd3f0dbf42a16a (diff)
[SCSI] scsi_remove_target: fix softlockup regression on hot remove
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. Cc: <stable@vger.kernel.org> Acked-by: Jack Wang <jack_wang@usish.com> LKML-Reference: <CAEhu1-6wq1YsNiscGMwP4ud0Q+MrViRzv=kcWCQSBNc8c68N5Q@mail.gmail.com> Reported-by: John Drescher <drescherjm@gmail.com> Tested-by: John Drescher <drescherjm@gmail.com> Signed-off-by: Dan Williams <djbw@fb.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
-rw-r--r--drivers/scsi/scsi_sysfs.c30
1 files changed, 14 insertions, 16 deletions
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 093d4f6a54d2..ce5224c92eda 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1031,33 +1031,31 @@ static void __scsi_remove_target(struct scsi_target *starget)
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);