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Message-ID: <93e6d58563268bd510a8ab01c7c72739309f1a4b.camel@kernel.org>
Subject: Re: [PATCH v3 1/2] SUNRPC: Fixup v4.1 backchannel request timeouts
From: Jeff Layton <jlayton@kernel.org>
To: Benjamin Coddington <bcodding@redhat.com>, 
	trond.myklebust@hammerspace.com, anna@kernel.org
Cc: linux-nfs@vger.kernel.org
Date: Thu, 04 Jan 2024 08:37:25 -0500
In-Reply-To: <e28038fba1243f00b0dd66b7c5296a1e181645ea.1702496910.git.bcodding@redhat.com>
References: 
	<e28038fba1243f00b0dd66b7c5296a1e181645ea.1702496910.git.bcodding@redhat.com>
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On Wed, 2023-12-13 at 14:49 -0500, Benjamin Coddington wrote:
> After commit 59464b262ff5 ("SUNRPC: SOFTCONN tasks should time out when o=
n
> the sending list"), any 4.1 backchannel tasks placed on the sending queue
> would immediately return with -ETIMEDOUT since their req timers are zero.
>=20
> Initialize the backchannel's rpc_rqst timeout parameters from the xprt's
> default timeout settings.
>=20
> Fixes: 59464b262ff5 ("SUNRPC: SOFTCONN tasks should time out when on the =
sending list")
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
>  net/sunrpc/xprt.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
>=20
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index 2364c485540c..6cc9ffac962d 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -651,9 +651,9 @@ static unsigned long xprt_abs_ktime_to_jiffies(ktime_=
t abstime)
>  		jiffies + nsecs_to_jiffies(-delta);
>  }
> =20
> -static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
> +static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req,
> +		const struct rpc_timeout *to)
>  {
> -	const struct rpc_timeout *to =3D req->rq_task->tk_client->cl_timeout;
>  	unsigned long majortimeo =3D req->rq_timeout;
> =20
>  	if (to->to_exponential)
> @@ -665,9 +665,10 @@ static unsigned long xprt_calc_majortimeo(struct rpc=
_rqst *req)
>  	return majortimeo;
>  }
> =20
> -static void xprt_reset_majortimeo(struct rpc_rqst *req)
> +static void xprt_reset_majortimeo(struct rpc_rqst *req,
> +		const struct rpc_timeout *to)
>  {
> -	req->rq_majortimeo +=3D xprt_calc_majortimeo(req);
> +	req->rq_majortimeo +=3D xprt_calc_majortimeo(req, to);
>  }
> =20
>  static void xprt_reset_minortimeo(struct rpc_rqst *req)
> @@ -675,7 +676,8 @@ static void xprt_reset_minortimeo(struct rpc_rqst *re=
q)
>  	req->rq_minortimeo +=3D req->rq_timeout;
>  }
> =20
> -static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst =
*req)
> +static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst =
*req,
> +		const struct rpc_timeout *to)
>  {
>  	unsigned long time_init;
>  	struct rpc_xprt *xprt =3D req->rq_xprt;
> @@ -684,8 +686,9 @@ static void xprt_init_majortimeo(struct rpc_task *tas=
k, struct rpc_rqst *req)
>  		time_init =3D jiffies;
>  	else
>  		time_init =3D xprt_abs_ktime_to_jiffies(task->tk_start);
> -	req->rq_timeout =3D task->tk_client->cl_timeout->to_initval;
> -	req->rq_majortimeo =3D time_init + xprt_calc_majortimeo(req);
> +
> +	req->rq_timeout =3D to->to_initval;
> +	req->rq_majortimeo =3D time_init + xprt_calc_majortimeo(req, to);
>  	req->rq_minortimeo =3D time_init + req->rq_timeout;
>  }
> =20
> @@ -713,7 +716,7 @@ int xprt_adjust_timeout(struct rpc_rqst *req)
>  	} else {
>  		req->rq_timeout =3D to->to_initval;
>  		req->rq_retries =3D 0;
> -		xprt_reset_majortimeo(req);
> +		xprt_reset_majortimeo(req, to);
>  		/* Reset the RTT counters =3D=3D "slow start" */
>  		spin_lock(&xprt->transport_lock);
>  		rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
> @@ -1886,7 +1889,7 @@ xprt_request_init(struct rpc_task *task)
>  	req->rq_snd_buf.bvec =3D NULL;
>  	req->rq_rcv_buf.bvec =3D NULL;
>  	req->rq_release_snd_buf =3D NULL;
> -	xprt_init_majortimeo(task, req);
> +	xprt_init_majortimeo(task, req, task->tk_client->cl_timeout);
> =20
>  	trace_xprt_reserve(req);
>  }
> @@ -1996,6 +1999,8 @@ xprt_init_bc_request(struct rpc_rqst *req, struct r=
pc_task *task)
>  	 */
>  	xbufp->len =3D xbufp->head[0].iov_len + xbufp->page_len +
>  		xbufp->tail[0].iov_len;
> +
> +	xprt_init_majortimeo(task, req, req->rq_xprt->timeout);
>  }
>  #endif
> =20

As I mentioned in the email thread here, I've been seeing some hangs
with v6.7-rc8 kernels when testing TLS support:

https://lore.kernel.org/linux-nfs/8C3DFB5D-B967-4D59-BFC5-7B25315DB9AB@redh=
at.com/T/#t

With this patchset in place, I've been unable to reproduce it.


I'm not sure if this is the right way to fix this, but this does seem to
be a real problem and I have a semi-reliable way to reproduce it if you
need me to test a fix for it.

Cheers,
--=20
Jeff Layton <jlayton@kernel.org>