Commit 8146c4e2 authored Jan 10, 2012 by Paul E. McKenney Committed by Paul E. McKenney Feb 21, 2012

rcu: Check for callback invocation from offline CPUs

Because quiescent states are now reported from offline CPUs in
CPU_DYING state, there is some possibility that such a CPU might
note the end of a grace period and attempt to start invoking
callbacks. This would be a very bad thing, and is supposed to
be prevented by the fact that the CPU_DYING CPU gets rid of all
its callbacks before reporting the quiescent state. However,
there is other CPU-offline code in the kernel, and it is quite
possible that someone will invoke RCU core processing from that
code. Therefore, this commit adds a warning for this case.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

parent 778d250a

kernel/rcutree.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1373,6 +1373,7 @@ static void rcu_do_batch(struct rcu_state rsp, struct rcu_data rdp)
		* races with call_rcu() from interrupt handlers.
		*/
		local_irq_save(flags);
		WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
		bl = rdp->blimit;
		trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl);
		list = rdp->nxtlist;

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