Patch "net sched actions: decrement module reference count after table flush." has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    net sched actions: decrement module reference count after table flush.

to the 4.4-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:
     net-sched-actions-decrement-module-reference-count-after-table-flush.patch
and it can be found in the queue-4.4 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 foo@baz Sat Mar 18 22:36:49 CST 2017
From: Roman Mashak <mrv@mojatatu.com>
Date: Fri, 24 Feb 2017 11:00:32 -0500
Subject: net sched actions: decrement module reference count after table flush.

From: Roman Mashak <mrv@mojatatu.com>


[ Upstream commit edb9d1bff4bbe19b8ae0e71b1f38732591a9eeb2 ]

When tc actions are loaded as a module and no actions have been installed,
flushing them would result in actions removed from the memory, but modules
reference count not being decremented, so that the modules would not be
unloaded.

Following is example with GACT action:

% sudo modprobe act_gact
% lsmod
Module                  Size  Used by
act_gact               16384  0
%
% sudo tc actions ls action gact
%
% sudo tc actions flush action gact
% lsmod
Module                  Size  Used by
act_gact               16384  1
% sudo tc actions flush action gact
% lsmod
Module                  Size  Used by
act_gact               16384  2
% sudo rmmod act_gact
rmmod: ERROR: Module act_gact is in use
....

After the fix:
% lsmod
Module                  Size  Used by
act_gact               16384  0
%
% sudo tc actions add action pass index 1
% sudo tc actions add action pass index 2
% sudo tc actions add action pass index 3
% lsmod
Module                  Size  Used by
act_gact               16384  3
%
% sudo tc actions flush action gact
% lsmod
Module                  Size  Used by
act_gact               16384  0
%
% sudo tc actions flush action gact
% lsmod
Module                  Size  Used by
act_gact               16384  0
% sudo rmmod act_gact
% lsmod
Module                  Size  Used by
%

Fixes: f97017cdefef ("net-sched: Fix actions flushing")
Signed-off-by: Roman Mashak <mrv@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/act_api.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -820,10 +820,8 @@ static int tca_action_flush(struct net *
 		goto out_module_put;
 
 	err = a.ops->walk(skb, &dcb, RTM_DELACTION, &a);
-	if (err < 0)
+	if (err <= 0)
 		goto out_module_put;
-	if (err == 0)
-		goto noflush_out;
 
 	nla_nest_end(skb, nest);
 
@@ -840,7 +838,6 @@ static int tca_action_flush(struct net *
 out_module_put:
 	module_put(a.ops->owner);
 err_out:
-noflush_out:
 	kfree_skb(skb);
 	return err;
 }


Patches currently in stable-queue which might be from mrv@mojatatu.com are

queue-4.4/net-sched-actions-decrement-module-reference-count-after-table-flush.patch