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| author | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-05-23 23:49:26 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-08-14 00:35:49 +0300 |
| commit | 383e13328373ae1e17119ff89c86ff5f9413f31c (patch) | |
| tree | 77bcdedf373eeede625403b406d4291d28803b60 /kernel/rcu | |
| parent | aeeacd9d844b2219d47e9010298b635c68a2a4c9 (diff) | |
| download | linux-383e13328373ae1e17119ff89c86ff5f9413f31c.tar.xz | |
rcu/nocb: Never downgrade ->nocb_defer_wakeup in wake_nocb_gp_defer()
Currently, wake_nocb_gp_defer() simply stores whatever waketype was
passed in, which can result in a RCU_NOCB_WAKE_FORCE being downgraded
to RCU_NOCB_WAKE, which could in turn delay callback processing.
This commit therefore adds a check so that wake_nocb_gp_defer() only
updates ->nocb_defer_wakeup when the update increases the forcefulness,
thus avoiding downgrades.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 7077ef7bea96..b9e00660af60 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1600,7 +1600,8 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype, { if (rdp->nocb_defer_wakeup == RCU_NOCB_WAKE_NOT) mod_timer(&rdp->nocb_timer, jiffies + 1); - WRITE_ONCE(rdp->nocb_defer_wakeup, waketype); + if (rdp->nocb_defer_wakeup < waketype) + WRITE_ONCE(rdp->nocb_defer_wakeup, waketype); trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, reason); } |