From: Arik Nemtsov <arik@wizery.com>
Date: Tue, 22 Feb 2011 22:22:24 +0000 (+0200)
Subject: wl12xx: fix potential race condition with TX queue watermark
X-Git-Tag: v2.6.39-rc1~468^2~158^2^2~69^2~7
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f4d08ddd3e60c79a141be36a5f3a7294c619291d;p=pandora-kernel.git

wl12xx: fix potential race condition with TX queue watermark

Check the conditions for the high/low TX queue watermarks when the
spin-lock is taken. This prevents race conditions as tx_queue_count and
the flag checked are only modified when the spin-lock is taken.

The following race was in mind:
- Queues are almost full and wl1271_op_tx() will stop the queues, but it
  doesn't get the spin-lock yet.
- (on another CPU) tx_work_locked() dequeues 15 skbs from this queue and
  tx_queue_count is updated to reflect this
- wl1271_op_tx() does not check tx_queue_count after taking the
  spin-lock and incorrectly stops the queue.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
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