On Mon, 2013-06-24 at 11:52 +0400, Stanislav Kinsbursky wrote:
> CPU#0 CPU#1
> ----------------------------- -----------------------------
> rpc_kill_sb
> sn->pipefs_sb = NULL rpc_release_client
> (UMOUNT_EVENT) rpc_free_auth
> rpc_pipefs_event
> rpc_get_client_for_event
> !atomic_inc_not_zero(cl_count)
> <skip the client>
> atomic_inc(cl_count)
> rpc_free_client
> rpc_clnt_remove_pipedir
> <skip client dir removing>
>
> To fix this, this patch does the following:
>
> 1) Calls RPC_PIPEFS_UMOUNT notification with sn->pipefs_sb_lock being held.
> 2) Removes SUNRPC client from the list AFTER pipes destroying.
> 3) Doesn't hold RPC client on notification: if client in the list, then it
> can't be destroyed while sn->pipefs_sb_lock in hold by notification caller.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> net/sunrpc/clnt.c | 5 +----
> net/sunrpc/rpc_pipe.c | 2 +-
> 2 files changed, 2 insertions(+), 5 deletions(-)
<snip>
> diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
> index c512448..efca2f7 100644
> --- a/net/sunrpc/rpc_pipe.c
> +++ b/net/sunrpc/rpc_pipe.c
> @@ -1165,7 +1165,6 @@ static void rpc_kill_sb(struct super_block *sb)
> goto out;
> }
> sn->pipefs_sb = NULL;
> - mutex_unlock(&sn->pipefs_sb_lock);
> dprintk("RPC: sending pipefs UMOUNT notification for net %p%s\n",
> net, NET_NAME(net));
> blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
> @@ -1173,6 +1172,7 @@ static void rpc_kill_sb(struct super_block *sb)
> sb);
> put_net(net);
> out:
> + mutex_unlock(&sn->pipefs_sb_lock);
Is this safe to do after the put_net()?
> kill_litter_super(sb);
> }
>
>
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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