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rcu: Check for callback invocation from offline CPUs

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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>
This commit is contained in:
Paul E. McKenney 2012-01-10 14:23:29 -08:00 committed by Paul E. McKenney
parent 778d250a29
commit 8146c4e2e2
1 changed files with 1 additions and 0 deletions
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kernel/rcutree.c
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@ -1373,6 +1373,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
* races with call_rcu() from interrupt handlers. * races with call_rcu() from interrupt handlers.
*/ */
local_irq_save(flags); local_irq_save(flags);
WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
bl = rdp->blimit; bl = rdp->blimit;
trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl); trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl);
list = rdp->nxtlist; list = rdp->nxtlist;