From: Scott Mayhew <smayhew@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: "anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
"dwysocha@redhat.com" <dwysocha@redhat.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 1/1] SUNRPC: Ensure XPRT_CONNECTED is cleared while handling TCP RST
Date: Fri, 14 Dec 2018 13:29:35 -0500 [thread overview]
Message-ID: <20181214182935.GI27213@coeurl.usersys.redhat.com> (raw)
In-Reply-To: <03049f893dfd265abb90fd2692bc41e1534f85d0.camel@hammerspace.com>
On Wed, 12 Dec 2018, Trond Myklebust wrote:
> On Wed, 2018-12-12 at 08:51 -0500, Dave Wysochanski wrote:
> > Commit 9b30889c548a changed the handling of TCP_CLOSE inside
> > xs_tcp_state_change. Prior to this change, the XPRT_CONNECTED bit
> > was cleared unconditionally inside xprt_disconnect_done, similar
> > to the handling of TCP_CLOSE_WAIT. After the change the clearing
> > of XPRT_CONNECTED depends on successfully queueing a work based
> > xprt_autoclose which depends on XPRT_LOCKED and may not happen.
> > This is significant in the case of an unexpected RST from the
> > server, as the client will only see xs_tcp_state_change called with
> > sk_state == TCP_CLOSE. Restore the unconditional clear_bit on
> > XPRT_CONNECTED while handling TCP_CLOSE and make it consistent
> > with handling TCP_CLOSE_WAIT.
> >
> > Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
> > ---
> > net/sunrpc/xprtsock.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> > index 8a5e823e0b33..b9789036051d 100644
> > --- a/net/sunrpc/xprtsock.c
> > +++ b/net/sunrpc/xprtsock.c
> > @@ -1492,6 +1492,7 @@ static void xs_tcp_state_change(struct sock
> > *sk)
> > if (sk->sk_err)
> > xprt_wake_pending_tasks(xprt, -sk->sk_err);
> > /* Trigger the socket release */
> > + clear_bit(XPRT_CONNECTED, &xprt->state);
> > xs_tcp_force_close(xprt);
> > }
> > out:
>
> Hi Dave,
>
> This isn't needed for 4.20 or newer because call_transmit() will now
> always call xprt_end_transmit().
Dave's script can also produce a hang on 4.20, but for a different
reason... if xs_reset_transport() is called on an xprt that has
XPRT_WRITE_SPACE set, then no further RPC tasks will be able to lock the
transport or connect it. Clearing XPRT_WRITE_SPACE in
xs_sock_reset_connection_flags() seems to fix that. I don't know if
XPRT_WRITE_SPACE counts as a "connection flag" though.
-Scott
> I suggest that a stable fix do
> something similar (perhaps conditional on the error returned by
> xprt_transmit()?).
>
> Cheers
> Trond
>
> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
>
>
prev parent reply other threads:[~2018-12-14 18:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-12 13:51 [PATCH 0/1] SUNRPC: Ensure XPRT_CONNECTED is cleared while handling TCP RST Dave Wysochanski
2018-12-12 13:51 ` [PATCH 1/1] " Dave Wysochanski
2018-12-12 16:56 ` Trond Myklebust
2018-12-12 17:47 ` Dave Wysochanski
2018-12-12 18:02 ` Trond Myklebust
2018-12-12 19:56 ` Dave Wysochanski
2019-01-08 12:46 ` Benjamin Coddington
2018-12-14 13:48 ` Dave Wysochanski
2018-12-14 18:29 ` Scott Mayhew [this message]
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