Patch "netvsc: fix deadlock betwen link status and removal" has been added to the 4.12-stable tree

Patch "netvsc: fix deadlock betwen link status and removal" has been added to the 4.12-stable tree

[gregkh]

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

    netvsc: fix deadlock betwen link status and removal

to the 4.12-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:
     netvsc-fix-deadlock-betwen-link-status-and-removal.patch
and it can be found in the queue-4.12 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 Thu Sep 14 23:20:23 PDT 2017
From: stephen hemminger <stephen@networkplumber.org>
Date: Thu, 24 Aug 2017 16:49:16 -0700
Subject: netvsc: fix deadlock betwen link status and removal

From: stephen hemminger <stephen@networkplumber.org>


[ Upstream commit 9b4e946ce14e20d7addbfb7d9139e604f9fda107 ]

There is a deadlock possible when canceling the link status
delayed work queue. The removal process is run with RTNL held,
and the link status callback is acquring RTNL.

Resolve the issue by using trylock and rescheduling.
If cancel is in process, that block it from happening.

Fixes: 122a5f6410f4 ("staging: hv: use delayed_work for netvsc_send_garp()")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/hyperv/netvsc_drv.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -1270,7 +1270,12 @@ static void netvsc_link_change(struct wo
 	bool notify = false, reschedule = false;
 	unsigned long flags, next_reconfig, delay;
 
-	rtnl_lock();
+	/* if changes are happening, comeback later */
+	if (!rtnl_trylock()) {
+		schedule_delayed_work(&ndev_ctx->dwork, LINKCHANGE_INT);
+		return;
+	}
+
 	net_device = rtnl_dereference(ndev_ctx->nvdev);
 	if (!net_device)
 		goto out_unlock;


Patches currently in stable-queue which might be from stephen@networkplumber.org are

queue-4.12/netvsc-fix-deadlock-betwen-link-status-and-removal.patch