Re: [PATCH] cifs: fix GlobalMid_Lock bug in cifs_reconnect

[Steve French <smfrench@gmail.com>]

tentatively merged into cifs-2.6.git for-next and to the github tree

On Thu, Jun 13, 2019 at 10:02 PM Ronnie Sahlberg <lsahlber@redhat.com> wrote:
>
> We can not hold the GlobalMid_Lock spinlock during the
> dfs processing in cifs_reconnect since it invokes things that may sleep
> and thus trigger :
>
> BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:23
>
> Thus we need to drop the spinlock during this code block.
>
> RHBZ: 1716743
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
> ---
>  fs/cifs/connect.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 8c4121da624e..8dd6637a3cbb 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -476,6 +476,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
>         spin_lock(&GlobalMid_Lock);
>         server->nr_targets = 1;
>  #ifdef CONFIG_CIFS_DFS_UPCALL
> +       spin_unlock(&GlobalMid_Lock);
>         cifs_sb = find_super_by_tcp(server);
>         if (IS_ERR(cifs_sb)) {
>                 rc = PTR_ERR(cifs_sb);
> @@ -493,6 +494,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
>         }
>         cifs_dbg(FYI, "%s: will retry %d target(s)\n", __func__,
>                  server->nr_targets);
> +       spin_lock(&GlobalMid_Lock);
>  #endif
>         if (server->tcpStatus == CifsExiting) {
>                 /* the demux thread will exit normally
> --
> 2.13.6
>


-- 
Thanks,

Steve