Messages in this thread Patch in this message | | | Date | Fri, 21 Aug 2015 19:43:03 +0200 | From | Oleg Nesterov <> | Subject | [PATCH v2 8/8] percpu-rwsem: cleanup the lockdep annotations in percpu_down_read() |
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Stolen from Peter's patch.
Change percpu_down_read() to use __down_read(), this way we can do rwsem_acquire_read() unconditionally at the start to make this code more symmetric and clean.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/locking/percpu-rwsem.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index 69704eb..5694849 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -69,14 +69,14 @@ static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val) void percpu_down_read(struct percpu_rw_semaphore *brw) { might_sleep(); - if (likely(update_fast_ctr(brw, +1))) { - rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_); + rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_); + + if (likely(update_fast_ctr(brw, +1))) return; - } - down_read(&brw->rw_sem); + /* Avoid rwsem_acquire_read() and rwsem_release() */ + __down_read(&brw->rw_sem); atomic_inc(&brw->slow_read_ctr); - /* avoid up_read()->rwsem_release() */ __up_read(&brw->rw_sem); } -- 1.5.5.1
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