Patch "dlm: free workqueues after the connections" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    dlm: free workqueues after the connections

to the 4.8-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:
     dlm-free-workqueues-after-the-connections.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 3a8db79889ce16930aff19b818f5b09651bb7644 Mon Sep 17 00:00:00 2001
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Sat, 8 Oct 2016 10:14:37 -0300
Subject: dlm: free workqueues after the connections

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

commit 3a8db79889ce16930aff19b818f5b09651bb7644 upstream.

After backporting commit ee44b4bc054a ("dlm: use sctp 1-to-1 API")
series to a kernel with an older workqueue which didn't use RCU yet, it
was noticed that we are freeing the workqueues in dlm_lowcomms_stop()
too early as free_conn() will try to access that memory for canceling
the queued works if any.

This issue was introduced by commit 0d737a8cfd83 as before it such
attempt to cancel the queued works wasn't performed, so the issue was
not present.

This patch fixes it by simply inverting the free order.

Fixes: 0d737a8cfd83 ("dlm: fix race while closing connections")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/dlm/lowcomms.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1656,16 +1656,12 @@ void dlm_lowcomms_stop(void)
 	mutex_lock(&connections_lock);
 	dlm_allow_conn = 0;
 	foreach_conn(stop_conn);
+	clean_writequeues();
+	foreach_conn(free_conn);
 	mutex_unlock(&connections_lock);
 
 	work_stop();
 
-	mutex_lock(&connections_lock);
-	clean_writequeues();
-
-	foreach_conn(free_conn);
-
-	mutex_unlock(&connections_lock);
 	kmem_cache_destroy(con_cache);
 }
 


Patches currently in stable-queue which might be from marcelo.leitner@gmail.com are

queue-4.8/dlm-free-workqueues-after-the-connections.patch