@@ -2025,8 +2025,17 @@ int scsi_error_handler(void *data)
* We never actually get interrupted because kthread_run
* disables signal delivery for the created thread.
*/
- while (!kthread_should_stop()) {
+ while (true) {
+ /*
+ * The sequence in kthread_stop() sets the stop flag first
+ * then wakes the process. To avoid missed wakeups, the task
+ * should always be in a non running state before the stop
+ * flag is checked
+ */
set_current_state(TASK_INTERRUPTIBLE);
+ if (kthread_should_stop())
+ break;
+
if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
shost->host_failed != shost->host_busy) {
SCSI_LOG_ERROR_RECOVERY(1,
This is a note to let you know that I have just added a patch titled scsi: fix scsi_error_handler vs. scsi_host_dev_release race to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt28. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 6456557d6c92685a1f31a09fe976ca6d0a3821d2 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@suse.com> Date: Thu, 27 Aug 2015 20:16:37 +0200 Subject: scsi: fix scsi_error_handler vs. scsi_host_dev_release race commit 537b604c8b3aa8b96fe35f87dd085816552e294c upstream. 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] 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> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/scsi/scsi_error.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) -- 1.9.1