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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
	peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com,
	edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com,
	oleg@redhat.com, sbw@mit.edu,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH tip/core/rcu 09/12] fs: Substitute rcu_access_pointer() for rcu_dereference_raw()
Date: Mon, 17 Feb 2014 13:35:56 -0800	[thread overview]
Message-ID: <1392672959-6386-9-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <1392672959-6386-1-git-send-email-paulmck@linux.vnet.ibm.com>

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 __alloc_fd(),
which simply compares the RCU-protected pointer against NULL with no
dereferencing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
---
 fs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file.c b/fs/file.c
index db25c2bdfe46..18f7d27855c4 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -497,7 +497,7 @@ repeat:
 	error = fd;
 #if 1
 	/* Sanity check */
-	if (rcu_dereference_raw(fdt->fd[fd]) != NULL) {
+	if (rcu_access_pointer(fdt->fd[fd]) != NULL) {
 		printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
 		rcu_assign_pointer(fdt->fd[fd], NULL);
 	}
-- 
1.8.1.5


  parent reply	other threads:[~2014-02-17 21:36 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-17 21:35 [PATCH tip/core/rcu 0/12] Miscellaneous fixes for 3.15 Paul E. McKenney
2014-02-17 21:35 ` [PATCH tip/core/rcu 01/12] rcu: Add ACCESS_ONCE() to ->n_force_qs_lh accesses Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 02/12] rcu: Stop tracking FSF's postal address Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 03/12] rcu: Remove ACCESS_ONCE() from jiffies Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 04/12] rcu: Glue ASCII strings together Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 05/12] rcu: Indentation and spacing fixes Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 06/12] rcu: Define rcu_assign_pointer() in terms of smp_store_release() Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 07/12] rcu: Disambiguate CONFIG_RCU_NOCB_CPUs Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 08/12] rcu: Move SRCU grace period work to power efficient workqueue Paul E. McKenney
2014-02-17 21:35   ` Paul E. McKenney [this message]
2014-02-17 22:00     ` [PATCH tip/core/rcu 09/12] fs: Substitute rcu_access_pointer() for rcu_dereference_raw() Josh Triplett
2014-02-17 23:05       ` Paul E. McKenney
2014-02-18  0:04         ` Josh Triplett
2014-02-18  0:27           ` Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 10/12] block: " Paul E. McKenney
2014-02-18 20:21     ` Jens Axboe
2014-02-17 21:35   ` [PATCH tip/core/rcu 11/12] notifier: " Paul E. McKenney
2014-02-17 21:35   ` [PATCH tip/core/rcu 12/12] rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c Paul E. McKenney
2014-02-17 22:01 ` [PATCH tip/core/rcu 0/12] Miscellaneous fixes for 3.15 Josh Triplett

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