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authorPaul E. McKenney <paulmck@kernel.org>2021-02-26 03:10:38 +0300
committerPaul E. McKenney <paulmck@kernel.org>2021-03-22 18:23:48 +0300
commit7abb18bd7567480e34f46d3512369ec49499064e (patch)
tree80c172e411f81a8009fbc6791d814b0e2033135d /include/linux/rcutree.h
parenta38fd8748464831584a19438cbb3082b5a2dab15 (diff)
downloadlinux-7abb18bd7567480e34f46d3512369ec49499064e.tar.xz
rcu: Provide polling interfaces for Tree RCU grace periods
There is a need for a non-blocking polling interface for RCU grace periods, so this commit supplies start_poll_synchronize_rcu() and poll_state_synchronize_rcu() for this purpose. Note that the existing get_state_synchronize_rcu() may be used if future grace periods are inevitable (perhaps due to a later call_rcu() invocation). The new start_poll_synchronize_rcu() is to be used if future grace periods might not otherwise happen. Finally, poll_state_synchronize_rcu() provides a lockless check for a grace period having elapsed since the corresponding call to either of the get_state_synchronize_rcu() or start_poll_synchronize_rcu(). As with get_state_synchronize_rcu(), the return value from either get_state_synchronize_rcu() or start_poll_synchronize_rcu() is passed in to a later call to either poll_state_synchronize_rcu() or the existing (might_sleep) cond_synchronize_rcu(). [ paulmck: Remove redundant smp_mb() per Frederic Weisbecker feedback. ] [ Update poll_state_synchronize_rcu() docbook per Frederic Weisbecker feedback. ] Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'include/linux/rcutree.h')
-rw-r--r--include/linux/rcutree.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index df578b73960f..b89b54130f49 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -41,6 +41,8 @@ void rcu_momentary_dyntick_idle(void);
void kfree_rcu_scheduler_running(void);
bool rcu_gp_might_be_stalled(void);
unsigned long get_state_synchronize_rcu(void);
+unsigned long start_poll_synchronize_rcu(void);
+bool poll_state_synchronize_rcu(unsigned long oldstate);
void cond_synchronize_rcu(unsigned long oldstate);
void rcu_idle_enter(void);