[dm-devel] Fw: [PATCH tip/core/rcu 3/9] drivers/md: Use rcu_dereference() for accessing rcu pointer

[Paul E. McKenney]

Should have Cc:ed you on this one, please accept my apologies for
failing to do so.

Would you guys like to push this patch, me to do so, or would you rather
that this patch be dropped?

							Thanx, Paul

----- Forwarded message from "Paul E. McKenney" <paulmck at linux.vnet.ibm.com> -----

Date: Tue, 28 Oct 2014 15:09:56 -0700
From: "Paul E. McKenney" <paulmck at linux.vnet.ibm.com>
To: linux-kernel at vger.kernel.org
Cc: mingo at kernel.org, laijs at cn.fujitsu.com, dipankar at in.ibm.com, akpm at linux-foundation.org, mathieu.desnoyers at efficios.com, josh at joshtriplett.org, tglx at linutronix.de, peterz at infradead.org, rostedt at goodmis.org, dhowells at redhat.com, edumazet at google.com, dvhart at linux.intel.com, fweisbec at gmail.com,
	oleg at redhat.com, bobby.prani at gmail.com, "Paul E. McKenney" <paulmck at linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 3/9] drivers/md: Use rcu_dereference() for accessing rcu pointer
X-Mailer: git-send-email 1.8.1.5

From: Pranith Kumar <bobby.prani at gmail.com>

Got Paul's email wrong the first time.

The map field in 'struct mapped_device' is an rcu pointer. Use rcu_dereference()
while accessing it.

Signed-off-by: Pranith Kumar <bobby.prani at gmail.com>
Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
---
 drivers/md/dm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 58f3927fd7cc..e7399362722e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2332,7 +2332,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,

 	merge_is_optional = dm_table_merge_is_optional(t);

-	old_map = md->map;
+	old_map = rcu_dereference(md->map);
 	rcu_assign_pointer(md->map, t);
 	md->immutable_target_type = dm_table_get_immutable_target_type(t);

@@ -2351,7 +2351,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
  */
 static struct dm_table *__unbind(struct mapped_device *md)
 {
-	struct dm_table *map = md->map;
+	struct dm_table *map = rcu_dereference(md->map);

 	if (!map)
 		return NULL;
@@ -2745,7 +2745,7 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 		goto out_unlock;
 	}

-	map = md->map;
+	map = rcu_dereference(md->map);

 	/*
 	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
@@ -2839,7 +2839,7 @@ int dm_resume(struct mapped_device *md)
 	if (!dm_suspended_md(md))
 		goto out;

-	map = md->map;
+	map = rcu_dereference(md->map);
 	if (!map || !dm_table_get_size(map))
 		goto out;

-- 
1.8.1.5


----- End forwarded message -----

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