Commits
Michal Hocko committed 537b604c8b3
scsi: fix scsi_error_handler vs. scsi_host_dev_release race
b9d5c6b7ef57 ("[SCSI] cleanup setting task state in
scsi_error_handler()") has introduced a race between scsi_error_handler
and scsi_host_dev_release resulting in the hang when the device goes
away because scsi_error_handler might miss a wake up:
CPU0 CPU1
scsi_error_handler scsi_host_dev_release
kthread_stop()
kthread_should_stop()
test_bit(KTHREAD_SHOULD_STOP)
set_bit(KTHREAD_SHOULD_STOP)
wake_up_process()
wait_for_completion()
set_current_state(TASK_INTERRUPTIBLE)
schedule()
The most straightforward solution seems to be to invert the ordering of
the set_current_state and kthread_should_stop.
The issue has been noticed during reboot test on a 3.0 based kernel but
the current code seems to be affected in the same way.
[jejb: additional comment added]
Cc: <stable@vger.kernel.org> # 3.6+
Reported-and-debugged-by: Mike Mayer <Mike.Meyer@teradata.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>