rcu: Make synchronize_rcu_mult() check for duplicates

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Currently, doing synchronize_rcu_mult(call_rcu, call_rcu) might
(or might not) wait for two RCU grace periods.  One approach is
of course "don't do that!", but in CONFIG_PREEMPT=n kernels,
synchronize_rcu_mult(call_rcu, call_rcu_sched) does exactly that.
This results in an ugly #ifdef in sched_cpu_deactivate().

This commit therefore makes __wait_rcu_gp() check for duplicates,
which in turn allows duplicates to be passed to synchronize_rcu_mult()
without risk of waiting twice on the same type of grace period.

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

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This commit is contained in:

Paul E. McKenney 2017-04-28 16:19:07 -07:00

parent a602538e46

commit 68ab0b4263

1 changed files with 11 additions and 2 deletions

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kernel/rcu/update.c

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