Messages in this thread Patch in this message | | | Date | Wed, 9 Oct 2013 20:50:41 +0200 | From | Oleg Nesterov <> | Subject | [PATCH v2 2/2] rcusync: make rcu_sync_enter() return "bool" |
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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 <oleg@redhat.com> --- 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
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