linux-kernel - Re: [PATCH 12/19] staging: lustre: make polling loop in ptlrpc_unregister

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Message-ID: <alpine.LFD.2.21.1801171533220.11282@casper.infradead.org>
Date:   Wed, 17 Jan 2018 15:33:32 +0000 (GMT)
From:   James Simmons <jsimmons@...radead.org>
To:     NeilBrown <neilb@...e.com>
cc:     Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        lkml <linux-kernel@...r.kernel.org>,
        lustre <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 12/19] staging: lustre: make polling loop in
 ptlrpc_unregister_bulk more obvious


> This use of l_wait_event() is a polling loop that re-checks
> every second.  Make this more obvious with a while loop
> and wait_event_idle_timeout().

Reviewed-by: James Simmons <jsimmons@...radead.org>
 
> Signed-off-by: NeilBrown <neilb@...e.com>
> ---
>  drivers/staging/lustre/lustre/ptlrpc/niobuf.c |   15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> index 0c2ded721c49..86883abaad2c 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> @@ -229,7 +229,6 @@ int ptlrpc_unregister_bulk(struct ptlrpc_request *req, int async)
>  {
>  	struct ptlrpc_bulk_desc *desc = req->rq_bulk;
>  	wait_queue_head_t *wq;
> -	struct l_wait_info lwi;
>  	int rc;
>  
>  	LASSERT(!in_interrupt());     /* might sleep */
> @@ -246,7 +245,7 @@ int ptlrpc_unregister_bulk(struct ptlrpc_request *req, int async)
>  
>  	/* the unlink ensures the callback happens ASAP and is the last
>  	 * one.  If it fails, it must be because completion just happened,
> -	 * but we must still l_wait_event() in this case to give liblustre
> +	 * but we must still wait_event() in this case to give liblustre
>  	 * a chance to run client_bulk_callback()
>  	 */
>  	mdunlink_iterate_helper(desc->bd_mds, desc->bd_md_max_brw);
> @@ -270,15 +269,17 @@ int ptlrpc_unregister_bulk(struct ptlrpc_request *req, int async)
>  		/* Network access will complete in finite time but the HUGE
>  		 * timeout lets us CWARN for visibility of sluggish LNDs
>  		 */
> -		lwi = LWI_TIMEOUT_INTERVAL(LONG_UNLINK * HZ,
> -					   HZ, NULL, NULL);
> -		rc = l_wait_event(*wq, !ptlrpc_client_bulk_active(req), &lwi);
> -		if (rc == 0) {
> +		int cnt = 0;
> +		while (cnt < LONG_UNLINK &&
> +		       (rc = wait_event_idle_timeout(*wq,
> +						     !ptlrpc_client_bulk_active(req),
> +						     HZ)) == 0)
> +			cnt += 1;
> +		if (rc > 0) {
>  			ptlrpc_rqphase_move(req, req->rq_next_phase);
>  			return 1;
>  		}
>  
> -		LASSERT(rc == -ETIMEDOUT);
>  		DEBUG_REQ(D_WARNING, req, "Unexpectedly long timeout: desc %p",
>  			  desc);
>  	}
> 
> 
>