Commit-ID: 34a64b6bb64b5cf193932e2b4394c5284732e008 Gitweb: http://git.kernel.org/tip/34a64b6bb64b5cf193932e2b4394c5284732e008 Author: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> AuthorDate: Thu, 29 Nov 2012 16:46:07 +0800 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Thu, 7 Feb 2013 15:17:01 -0800 srcu: Update synchronize_srcu()'s comments The core of SRCU is changed, but synchronize_srcu()'s comments describe the old algorithm. This commit therefore updates them to match the new algorithm. Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> --- kernel/srcu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/srcu.c b/kernel/srcu.c index 7cf5bab..f098f17 100644 --- a/kernel/srcu.c +++ b/kernel/srcu.c @@ -450,10 +450,12 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount) * synchronize_srcu - wait for prior SRCU read-side critical-section completion * @sp: srcu_struct with which to synchronize. * - * Flip the completed counter, and wait for the old count to drain to zero. - * As with classic RCU, the updater must use some separate means of - * synchronizing concurrent updates. Can block; must be called from - * process context. + * Wait for the count to drain to zero of both indexes. To avoid the + * possible starvation of synchronize_srcu(), it waits for the count of + * the index=((->completed & 1) ^ 1) to drain to zero at first, + * and then flip the completed and wait for the count of the other index. + * + * Can block; must be called from process context. * * Note that it is illegal to call synchronize_srcu() from the corresponding * SRCU read-side critical section; doing so will result in deadlock. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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