From: Roland Dreier <rolandd@cisco.com>
Date: Tue, 19 Aug 2008 22:01:32 +0000 (-0700)
Subject: IPoIB: Fix deadlock on RTNL in ipoib_stop()
X-Git-Tag: v2.6.27-rc5~52^2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a77a57a1a22afc31891d95879fe3cf2ab03838b0;p=pandora-kernel.git

IPoIB: Fix deadlock on RTNL in ipoib_stop()

Commit c8c2afe3 ("IPoIB: Use rtnl lock/unlock when changing device
flags") added a call to rtnl_lock() in ipoib_mcast_join_task(), which
is run from the ipoib_workqueue.  However, ipoib_stop() (which is run
inside rtnl_lock()) flushes this workqueue, which leads to a deadlock
if the join task is pending.

Fix this by simply not flushing the workqueue from ipoib_stop().  It
turns out that we really don't care about workqueue tasks running
during or after ipoib_stop(), as long as we make sure to flush the
workqueue before unregistering a netdev.

This fixes <https://bugs.openfabrics.org/show_bug.cgi?id=1114>.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
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