From: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Date: Thu, 10 Feb 2011 14:11:28 +0000 (+0000)
Subject: IB/qib: Fix double add_timer()
X-Git-Tag: v2.6.38-rc6~26^2^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=414ed90cee32486c50f91b28990443e0dc21c868;p=pandora-kernel.git

IB/qib: Fix double add_timer()

The following panic BUG_ON occurs during qib testing:

    Kernel BUG at include/linux/timer.h:82

    RIP  [<ffffffff881f7109>] :ib_qib:start_timer+0x73/0x89
     RSP <ffffffff80425bd0>
     <0>Kernel panic - not syncing: Fatal exception
     <0>Dumping qib trace buffer from panic
    qib_set_lid INFO: IB0:1 got a lid: 0xf8
    Done dumping qib trace buffer
    BUG: warning at kernel/panic.c:137/panic() (Tainted: G

The flaw is due to a missing state test when processing responses that
results in an add_timer() call when the same timer is already queued.
This code was executing in parallel with a QP destroy on another CPU
that had changed the state to reset, but the missing test caused to
response handling code to run on into the panic.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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