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

[Pavel Shilovsky <piastryyy@gmail.com>]

Acked-by: Pavel Shilovsky <pshilov@microsoft.com>

--
Best regards,
Pavel Shilovsky

чт, 13 июн. 2019 г. в 20:57, 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