From: Arjan van de Ven <arjan@linux.intel.com>
Date: Thu, 17 Jun 2010 10:02:15 +0000 (+0100)
Subject: serial: fix wakup races in the mrst_max3110 driver
X-Git-Tag: v2.6.36-rc1~294^2~60
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d6e679b474c096f1125087e789e7af8886de39d3;p=pandora-kernel.git

serial: fix wakup races in the mrst_max3110 driver

The mrst_max3110 driver had a set of unsafe wakeup sequences
along the following line:

if (!atomic_read(&foo)) {
  atomic_set(&foo, 1);
  wake_up(worker_thread);
}
and the worker thread would do

if (atomic_read(&foo)) {
  do_work();
  atomic_set(&foo, 0);
}

which can result in various missed wakups due to test-then-set races,
as well as due to clear-after-work instead of clear-before-work.

This patch fixes these races by using the proper bit test-and-set operations,
and by doing clear-before-work.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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