rcu: Tighten rcu_advance_cbs_nowake() checks

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Currently, rcu_advance_cbs_nowake() checks that a grace period is in
progress, however, that grace period could end just after the check.
This commit rechecks that a grace period is still in progress while
holding the rcu_node structure's lock.  The grace period cannot end while
the current CPU's rcu_node structure's ->lock is held, thus avoiding
false positives from the WARN_ON_ONCE().

As Daniel Vacek noted, it is not necessary for the rcu_node structure
to have a CPU that has not yet passed through its quiescent state.

Tested-by: Guillaume Morin <guillaume@morinfr.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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This commit is contained in:

Paul E. McKenney 2021-09-17 15:04:48 -07:00

parent 8c0abfd6d2

commit 614ddad17f

1 changed files with 4 additions and 3 deletions

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kernel/rcu/tree.c

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