Re: [PATCH 1/3] jbd2,rcu: correctly use RCU

[Ted Ts'o <tytso@mit.edu>]

On Thu, Jun 16, 2011 at 09:47:04AM +0800, Lai Jiangshan wrote:
> In read site, we need to use local_ptr = rcu_dereference(),
> and then use this local_ptr to read the content.
> 
> In update site, we should assign/publish the new object/pointer after
> the content of the new object/pointer is fully initialized,
> and we can't not touch the object after the pointer assignment.
> rcu_assign_pointer() is need for the assignement.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>

Thanks, applied.

> @@ -2447,24 +2447,25 @@ const char *jbd2_dev_to_name(dev_t device)
>  	int	i = hash_32(device, CACHE_SIZE_BITS);
>  	char	*ret;
>  	struct block_device *bd;
> -	static struct devname_cache *new_dev;
> +	static struct devname_cache *cache;

I also removed the static modifier to the struct devname_cache
pointer.  It's pointless, and in fact introduces a bug if two CPU's
try to run jbd2_dev_to_name() at the same time.

						- Ted