[RESEND PATCH] drivers/md: Use rcu_dereference() for accessing rcu pointer

[RESEND PATCH] drivers/md: Use rcu_dereference() for accessing rcu pointer

[Pranith Kumar]

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@gmail.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 746411b..fbdf0bb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2211,7 +2211,7 @@ 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);
 
@@ -2230,7 +2230,7 @@ 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;
@@ -2624,7 +2624,7 @@ 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.
@@ -2718,7 +2718,7 @@ 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;
 
-- 
1.9.1

Re: [RESEND PATCH] drivers/md: Use rcu_dereference() for accessing rcu pointer

[Paul E. McKenney]

On Sun, Sep 28, 2014 at 11:05:04AM -0400, Pranith Kumar wrote:
> 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@gmail.com>

OK, I now have all three queued (including the extraneous first line of
the commit log above...), will see what 0day thinks of it.

							Thanx, Paul

> ---
>  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 746411b..fbdf0bb 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -2211,7 +2211,7 @@ 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);
> 
> @@ -2230,7 +2230,7 @@ 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;
> @@ -2624,7 +2624,7 @@ 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.
> @@ -2718,7 +2718,7 @@ 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;
> 
> -- 
> 1.9.1
>