[PATCH] Fix RCU race in access of nohz_cpu_mask
Accessing nohz_cpu_mask before incrementing rcp->cur is racy. It can cause tickless idle CPUs to be included in rsp->cpumask, which will extend graceperiods unnecessarily. Fix this race. It has been tested using extensions to RCU torture module that forces various CPUs to become idle. Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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