linux-kernel - Re: [lustre-devel] [PATCH 15/16] staging: lustre: use explicit poll loop in ptlrpc_unregister

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Message-ID: <D65D8A40.C5E44%paf@cray.com>
Date:   Mon, 18 Dec 2017 21:09:18 +0000
From:   Patrick Farrell <paf@...y.com>
To:     NeilBrown <neilb@...e.com>, Oleg Drokin <oleg.drokin@...el.com>,
        "Andreas Dilger" <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     lkml <linux-kernel@...r.kernel.org>,
        lustre <lustre-devel@...ts.lustre.org>
Subject: Re: [lustre-devel] [PATCH 15/16] staging: lustre: use explicit poll
 loop in ptlrpc_unregister_reply

This should not contribute to load, since it¹s called out of the ptlrpcd
daemons.

On 12/18/17, 1:18 AM, "lustre-devel on behalf of NeilBrown"
<lustre-devel-bounces@...ts.lustre.org on behalf of neilb@...e.com> wrote:

>replace l_wait_event() with wait_event_timeout() and explicit
>loop.  This approach is easier to understand.
>
>Signed-off-by: NeilBrown <neilb@...e.com>
>---
> drivers/staging/lustre/lustre/ptlrpc/client.c |   14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
>diff --git a/drivers/staging/lustre/lustre/ptlrpc/client.c
>b/drivers/staging/lustre/lustre/ptlrpc/client.c
>index 3e6d22beb9f5..bb8c9ab68f5f 100644
>--- a/drivers/staging/lustre/lustre/ptlrpc/client.c
>+++ b/drivers/staging/lustre/lustre/ptlrpc/client.c
>@@ -2500,7 +2500,6 @@ static int ptlrpc_unregister_reply(struct
>ptlrpc_request *request, int async)
> {
> 	int rc;
> 	wait_queue_head_t *wq;
>-	struct l_wait_info lwi;
> 
> 	/* Might sleep. */
> 	LASSERT(!in_interrupt());
>@@ -2543,16 +2542,17 @@ static int ptlrpc_unregister_reply(struct
>ptlrpc_request *request, int async)
> 		 * Network access will complete in finite time but the HUGE
> 		 * timeout lets us CWARN for visibility of sluggish NALs
> 		 */
>-		lwi = LWI_TIMEOUT_INTERVAL(LONG_UNLINK * HZ,
>-					   HZ, NULL, NULL);
>-		rc = l_wait_event(*wq, !ptlrpc_client_recv_or_unlink(request),
>-				  &lwi);
>-		if (rc == 0) {
>+		int cnt = 0;
>+		while (cnt < LONG_UNLINK &&
>+		       (rc = wait_event_timeout(*wq,
>+						!ptlrpc_client_recv_or_unlink(request),
>+						HZ)) == 0)
>+			cnt += 1;
>+		if (rc > 0) {
> 			ptlrpc_rqphase_move(request, request->rq_next_phase);
> 			return 1;
> 		}
> 
>-		LASSERT(rc == -ETIMEDOUT);
> 		DEBUG_REQ(D_WARNING, request,
> 			  "Unexpectedly long timeout receiving_reply=%d req_ulinked=%d
>reply_unlinked=%d",
> 			  request->rq_receiving_reply,
>
>
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