From: Joe Lawrence Date: Fri, 3 Oct 2014 13:58:34 +0000 (-0400) Subject: team: avoid race condition in scheduling delayed work X-Git-Tag: fixes-against-v3.18-rc2~144^2^2~8 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=47549650abd13d873fd2e5fc218db19e21031074;p=pandora-kernel.git team: avoid race condition in scheduling delayed work When team_notify_peers and team_mcast_rejoin are called, they both reset their respective .count_pending atomic variable. Then when the actual worker function is executed, the variable is atomically decremented. This pattern introduces a potential race condition where the .count_pending rolls over and the worker function keeps rescheduling until .count_pending decrements to zero again: THREAD 1 THREAD 2 ======== ======== team_notify_peers(teamX) atomic_set count_pending = 1 schedule_delayed_work team_notify_peers(teamX) atomic_set count_pending = 1 team_notify_peers_work atomic_dec_and_test count_pending = 0 (return) schedule_delayed_work team_notify_peers_work atomic_dec_and_test count_pending = -1 schedule_delayed_work (repeat until count_pending = 0) Instead of assigning a new value to .count_pending, use atomic_add to tack-on the additional desired worker function invocations. Signed-off-by: Joe Lawrence Acked-by: Jiri Pirko Fixes: fc423ff00df3a19554414ee ("team: add peer notification") Fixes: 492b200efdd20b8fcfdac87 ("team: add support for sending multicast rejoins") Signed-off-by: David S. Miller --- Reading git-diff-tree failed