From 77d8485a8b5416c615b6acd95f01bfcacd7d81ff Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 8 Jul 2010 17:38:59 -0700 Subject: rcu: improve kerneldoc for rcu_read_lock(), call_rcu(), and synchronize_rcu() Make it explicit that new RCU read-side critical sections that start after call_rcu() and synchronize_rcu() start might still be running after the end of the relevant grace period. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'include/linux/rcupdate.h') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index b124bc6a75a..3e1b6625553 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -450,7 +450,7 @@ extern int rcu_my_thread_group_empty(void); * until after the all the other CPUs exit their critical sections. * * Note, however, that RCU callbacks are permitted to run concurrently - * with RCU read-side critical sections. One way that this can happen + * with new RCU read-side critical sections. One way that this can happen * is via the following sequence of events: (1) CPU 0 enters an RCU * read-side critical section, (2) CPU 1 invokes call_rcu() to register * an RCU callback, (3) CPU 0 exits the RCU read-side critical section, @@ -608,11 +608,13 @@ extern void wakeme_after_rcu(struct rcu_head *head); /** * call_rcu() - Queue an RCU callback for invocation after a grace period. * @head: structure to be used for queueing the RCU updates. - * @func: actual update function to be invoked after the grace period + * @func: actual callback function to be invoked after the grace period * - * The update function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU - * read-side critical sections have completed. RCU read-side critical + * The callback function will be invoked some time after a full grace + * period elapses, in other words after all pre-existing RCU read-side + * critical sections have completed. However, the callback function + * might well execute concurrently with RCU read-side critical sections + * that started after call_rcu() was invoked. RCU read-side critical * sections are delimited by rcu_read_lock() and rcu_read_unlock(), * and may be nested. */ @@ -622,9 +624,9 @@ extern void call_rcu(struct rcu_head *head, /** * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period. * @head: structure to be used for queueing the RCU updates. - * @func: actual update function to be invoked after the grace period + * @func: actual callback function to be invoked after the grace period * - * The update function will be invoked some time after a full grace + * The callback function will be invoked some time after a full grace * period elapses, in other words after all currently executing RCU * read-side critical sections have completed. call_rcu_bh() assumes * that the read-side critical sections end on completion of a softirq -- cgit v1.2.3