wl12xx: fix potential race condition with TX queue watermark
authorArik Nemtsov <arik@wizery.com>
Tue, 22 Feb 2011 22:22:24 +0000 (00:22 +0200)
committerLuciano Coelho <coelho@ti.com>
Wed, 23 Feb 2011 09:14:55 +0000 (11:14 +0200)
commitf4d08ddd3e60c79a141be36a5f3a7294c619291d
tree4b0289650beaa14e2f7c9ea7a66217a71d6cfbc5
parent6dc9fb3c78a78982f6418b6cf457140f7afa658d
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>
drivers/net/wireless/wl12xx/main.c