Re: [PATCH 6/8] libceph: avoid dropping con mutex before fault

[Alex Elder <elder@inktank.com>]

On 07/30/2012 10:59 AM, Sage Weil wrote:
> The ceph_fault() function takes the con mutex, so we should avoid
> dropping it before calling it.  This fixes a potential race with
> another thread calling ceph_con_close(), or _open(), or similar (we
> don't reverify con->state after retaking the lock).
> 
> Add annotation so that lockdep realizes we will drop the mutex before
> returning.
> 
> Signed-off-by: Sage Weil <sage@inktank.com>

Looks good.

Reviewed-by: Alex Elder <elder@inktank.com>

> ---
>  net/ceph/messenger.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index feb5a2a..c3b628c 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -2336,7 +2336,6 @@ done_unlocked:
>  	return;
>  
>  fault:
> -	mutex_unlock(&con->mutex);
>  	ceph_fault(con);     /* error/fault path */
>  	goto done_unlocked;
>  }
> @@ -2347,9 +2346,8 @@ fault:
>   * exponential backoff
>   */
>  static void ceph_fault(struct ceph_connection *con)
> +	__releases(con->mutex)
>  {
> -	mutex_lock(&con->mutex);
> -
>  	pr_err("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
>  	       ceph_pr_addr(&con->peer_addr.in_addr), con->error_msg);
>  	dout("fault %p state %lu to peer %s\n",
>