linux-kernel - [PATCH 4.2.y-ckt 040/206] aacraid: Fix for aac_command

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Message-Id: <1465507015-23052-41-git-send-email-kamal@canonical.com>
Date:	Thu,  9 Jun 2016 14:14:09 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Raghava Aditya Renukunta <RaghavaAditya.Renukunta@...rosemi.com>,
	"Martin K . Petersen" <martin.petersen@...cle.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 040/206] aacraid: Fix for aac_command_thread hang

4.2.8-ckt12 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@...rosemi.com>

commit fc4bf75ea300a5e62a2419f89dd0e22189dd7ab7 upstream.

Typically under error conditions, it is possible for aac_command_thread()
to miss the wakeup from kthread_stop() and go back to sleep, causing it
to hang aac_shutdown.

In the observed scenario, the adapter is not functioning correctly and so
aac_fib_send() never completes (or time-outs depending on how it was
called). Shortly after aac_command_thread() starts it performs
aac_fib_send(SendHostTime) which hangs. When aac_probe_one
/aac_get_adapter_info send time outs, kthread_stop is called which breaks
the command thread out of it's hang.

The code will still go back to sleep in schedule_timeout() without
checking kthread_should_stop() so it causes aac_probe_one to hang until
the schedule_timeout() which is 30 minutes.

Fixed by: Adding another kthread_should_stop() before schedule_timeout()
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@...rosemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/scsi/aacraid/commsup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c
index e7344ae..9410ffe 100644
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -1999,6 +1999,10 @@ int aac_command_thread(void *data)
 		if (difference <= 0)
 			difference = 1;
 		set_current_state(TASK_INTERRUPTIBLE);
+
+		if (kthread_should_stop())
+			break;
+
 		schedule_timeout(difference);

 		if (kthread_should_stop())
-- 
2.7.4