Change rcu_sync_enter() to return "need_sync" to let the caller know whether we did the FAST -> SLOW transition or not.
This is particularly useful in exclusive mode, for example percpu_down_write() can avoid clear_fast_ctr() if rcu_sync_enter() returns F. Signed-off-by: Oleg Nesterov <[email protected]> --- include/linux/rcusync.h | 2 +- kernel/rcusync.c | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/rcusync.h b/include/linux/rcusync.h index aaea86a..8430921 100644 --- a/include/linux/rcusync.h +++ b/include/linux/rcusync.h @@ -31,7 +31,7 @@ static inline bool rcu_sync_is_idle(struct rcu_sync_struct *rss) extern void rcu_sync_init(struct rcu_sync_struct *, enum rcu_sync_type, bool excl); -extern void rcu_sync_enter(struct rcu_sync_struct *); +extern bool rcu_sync_enter(struct rcu_sync_struct *); extern void rcu_sync_exit(struct rcu_sync_struct *); extern void rcu_sync_dtor(struct rcu_sync_struct *); diff --git a/kernel/rcusync.c b/kernel/rcusync.c index 03ddc61..21a6695 100644 --- a/kernel/rcusync.c +++ b/kernel/rcusync.c @@ -59,7 +59,7 @@ void rcu_sync_init(struct rcu_sync_struct *rss, rss->gp_type = type; } -void rcu_sync_enter(struct rcu_sync_struct *rss) +bool rcu_sync_enter(struct rcu_sync_struct *rss) { bool need_wait, need_sync; @@ -90,6 +90,8 @@ void rcu_sync_enter(struct rcu_sync_struct *rss) */ BUG_ON(rss->gp_state != GP_PASSED); } + + return need_sync; } static void rcu_sync_func(struct rcu_head *rcu) -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
