linux-kernel - Re: [PATCH 09/19] staging: lustre: open code polling loop instead of using l_wait

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Message-ID: <alpine.LFD.2.21.1801171531500.11282@casper.infradead.org>
Date:   Wed, 17 Jan 2018 15:32:04 +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 09/19] staging: lustre: open code polling loop instead
 of using l_wait_event()


> Two places that LWI_TIMEOUT_INTERVAL() is used, the outcome is a
> simple polling loop that polls every second for some event (with a
> limit).
> 
> So write a simple loop to make this more apparent.

Reviewed-by: James Simmons <jsimmons@...radead.org>
 
> Signed-off-by: NeilBrown <neilb@...e.com>
> ---
>  drivers/staging/lustre/lustre/llite/llite_lib.c |   11 +++++------
>  drivers/staging/lustre/lustre/lov/lov_request.c |   12 +++++-------
>  2 files changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
> index 33dc15e9aebb..f6642fa30428 100644
> --- a/drivers/staging/lustre/lustre/llite/llite_lib.c
> +++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
> @@ -1984,8 +1984,7 @@ void ll_umount_begin(struct super_block *sb)
>  	struct ll_sb_info *sbi = ll_s2sbi(sb);
>  	struct obd_device *obd;
>  	struct obd_ioctl_data *ioc_data;
> -	wait_queue_head_t waitq;
> -	struct l_wait_info lwi;
> +	int cnt = 0;
>  
>  	CDEBUG(D_VFSTRACE, "VFS Op: superblock %p count %d active %d\n", sb,
>  	       sb->s_count, atomic_read(&sb->s_active));
> @@ -2021,10 +2020,10 @@ void ll_umount_begin(struct super_block *sb)
>  	 * and then continue. For now, we just periodically checking for vfs
>  	 * to decrement mnt_cnt and hope to finish it within 10sec.
>  	 */
> -	init_waitqueue_head(&waitq);
> -	lwi = LWI_TIMEOUT_INTERVAL(10 * HZ,
> -				   HZ, NULL, NULL);
> -	l_wait_event(waitq, may_umount(sbi->ll_mnt.mnt), &lwi);
> +	while (cnt < 10 && !may_umount(sbi->ll_mnt.mnt)) {
> +		schedule_timeout_uninterruptible(HZ);
> +		cnt ++;
> +	}
>  
>  	schedule();
>  }
> diff --git a/drivers/staging/lustre/lustre/lov/lov_request.c b/drivers/staging/lustre/lustre/lov/lov_request.c
> index fb3b7a7fa32a..c1e58fcc30b3 100644
> --- a/drivers/staging/lustre/lustre/lov/lov_request.c
> +++ b/drivers/staging/lustre/lustre/lov/lov_request.c
> @@ -99,8 +99,7 @@ static int lov_check_set(struct lov_obd *lov, int idx)
>   */
>  static int lov_check_and_wait_active(struct lov_obd *lov, int ost_idx)
>  {
> -	wait_queue_head_t waitq;
> -	struct l_wait_info lwi;
> +	int cnt = 0;
>  	struct lov_tgt_desc *tgt;
>  	int rc = 0;
>  
> @@ -125,11 +124,10 @@ static int lov_check_and_wait_active(struct lov_obd *lov, int ost_idx)
>  
>  	mutex_unlock(&lov->lov_lock);
>  
> -	init_waitqueue_head(&waitq);
> -	lwi = LWI_TIMEOUT_INTERVAL(obd_timeout * HZ,
> -				   HZ, NULL, NULL);
> -
> -	rc = l_wait_event(waitq, lov_check_set(lov, ost_idx), &lwi);
> +	while (cnt < obd_timeout && !lov_check_set(lov, ost_idx)) {
> +		schedule_timeout_uninterruptible(HZ);
> +		cnt ++;
> +	}
>  	if (tgt->ltd_active)
>  		return 1;
>  
> 
> 
>