From: Ben Greear <greearb@candelatech.com>
Date: Wed, 20 Feb 2013 17:41:09 +0000 (-0800)
Subject: mac80211: Fix crash due to un-canceled work-items
X-Git-Tag: v3.9-rc3~36^2~28^2^2~1^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=499218595a2e8296b7492af32fcca141b7b8184a;p=pandora-kernel.git

mac80211: Fix crash due to un-canceled work-items

Some mlme work structs are not cancelled on disassociation
nor interface deletion, which leads to them running after
the memory has been freed

There is not a clean way to cancel these in the disassociation
logic because they must be canceled outside of the ifmgd->mtx
lock, so just cancel them in mgd_stop logic that tears down
the station.

This fixes the crashes we see in 3.7.9+.  The crash stack
trace itself isn't so helpful, but this warning gives
more useful info:

WARNING: at /home/greearb/git/linux-3.7.dev.y/lib/debugobjects.c:261 debug_print_object+0x7c/0x8d()
ODEBUG: free active (active state 0) object type: work_struct hint: ieee80211_sta_monitor_work+0x0/0x14 [mac80211]
Modules linked in: [...]
Pid: 14743, comm: iw Tainted: G         C O 3.7.9+ #11
Call Trace:
 [<ffffffff81087ef8>] warn_slowpath_common+0x80/0x98
 [<ffffffff81087fa4>] warn_slowpath_fmt+0x41/0x43
 [<ffffffff812a2608>] debug_print_object+0x7c/0x8d
 [<ffffffff812a2bca>] debug_check_no_obj_freed+0x95/0x1c3
 [<ffffffff8114cc69>] slab_free_hook+0x70/0x79
 [<ffffffff8114ea3e>] kfree+0x62/0xb7
 [<ffffffff8149f465>] netdev_release+0x39/0x3e
 [<ffffffff8136ad67>] device_release+0x52/0x8a
 [<ffffffff812937db>] kobject_release+0x121/0x158
 [<ffffffff81293612>] kobject_put+0x4c/0x50
 [<ffffffff8148f0d7>] netdev_run_todo+0x25c/0x27e

Cc: stable@vger.kernel.org
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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