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authorSimon Derr <simon.derr@bull.net>2012-09-17 15:16:28 +0200
committerEric Van Hensbergen <ericvh@gmail.com>2012-09-17 14:54:11 -0500
commit0462194d358c2e040282d4d1a4fd1aab84417e42 (patch)
treeb89845ce0e5bccbbf681b12e07cc4d4c72105c2c /samples
parente549c1337133e85a6d6bc868d2d141a61a80975c (diff)
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9P: Fix race in p9_read_work()
Race scenario between p9_read_work() and p9_poll_mux() Data arrive, Rworksched is set, p9_read_work() is called. thread A thread B p9_read_work() . reads data . checks if new data ready. No. . gets preempted . More data arrive, p9_poll_mux() is called. . . . p9_poll_mux() . . if (!test_and_set_bit(Rworksched, . &m->wsched)) { . schedule_work(&m->rq); . } . . -> does not schedule work because . Rworksched is set . . clear_bit(Rworksched, &m->wsched); return; No work has been scheduled, and yet data are waiting. Currently p9_read_work() checks if there is data to read, and if not, it clears Rworksched. I think it should clear Rworksched first, and then check if there is data to read. Signed-off-by: Simon Derr <simon.derr@bull.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
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