From: David Vernet <void@xxxxxxxxxxxxx> The rcu_sync_enter() function is used by updaters to force RCU readers (e.g. percpu-rwsem) to use their slow paths during an update. This is accomplished by setting the ->gp_state of the rcu_sync structure to GP_ENTER. In the case of percpu-rwsem, the readers' slow path waits on a semaphore instead of just incrementing a reader count. Each updater invokes the rcu_sync_exit() function to signal to readers that they may again take their fastpaths. The rcu_sync_exit() function sets the ->gp_state of the rcu_sync structure to GP_EXIT, and if all goes well, after a grace period the ->gp_state reverts back to GP_IDLE. Unfortunately, the rcu_sync_enter() function currently has a comment incorrectly stating that rcu_sync_exit() (by an updater) will re-enable reader "slowpaths". This patch changes the comment to state that this function re-enables reader fastpaths. Signed-off-by: David Vernet <void@xxxxxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/sync.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c index 33d896d85902..5cefc702158f 100644 --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -111,7 +111,7 @@ static void rcu_sync_func(struct rcu_head *rhp) * a slowpath during the update. After this function returns, all * subsequent calls to rcu_sync_is_idle() will return false, which * tells readers to stay off their fastpaths. A later call to - * rcu_sync_exit() re-enables reader slowpaths. + * rcu_sync_exit() re-enables reader fastpaths. * * When called in isolation, rcu_sync_enter() must wait for a grace * period, however, closely spaced calls to rcu_sync_enter() can -- 2.31.1.189.g2e36527f23
