lkml.org 
[lkml]   [2014]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH tip/core/rcu 10/12] block: Substitute rcu_access_pointer() for rcu_dereference_raw()
Date
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

(Trivial patch.)

If the code is looking at the RCU-protected pointer itself, but not
dereferencing it, the rcu_dereference() functions can be downgraded to
rcu_access_pointer(). This commit makes this downgrade in blkg_destroy()
and ioc_destroy_icq(), both of which simply compare the RCU-protected
pointer against another pointer with no dereferencing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
---
block/blk-cgroup.c | 2 +-
block/blk-ioc.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4e491d9b5292..b6e95b5e262f 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -336,7 +336,7 @@ static void blkg_destroy(struct blkcg_gq *blkg)
* under queue_lock. If it's not pointing to @blkg now, it never
* will. Hint assignment itself can race safely.
*/
- if (rcu_dereference_raw(blkcg->blkg_hint) == blkg)
+ if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
rcu_assign_pointer(blkcg->blkg_hint, NULL);

/*
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 242df01413f6..1a27f45ec776 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -68,7 +68,7 @@ static void ioc_destroy_icq(struct io_cq *icq)
* under queue_lock. If it's not pointing to @icq now, it never
* will. Hint assignment itself can race safely.
*/
- if (rcu_dereference_raw(ioc->icq_hint) == icq)
+ if (rcu_access_pointer(ioc->icq_hint) == icq)
rcu_assign_pointer(ioc->icq_hint, NULL);

ioc_exit_icq(icq);
--
1.8.1.5


\
 
 \ /
  Last update: 2014-02-18 04:01    [W:0.102 / U:0.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site