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From: Bart Van Assche <bvanassche@acm.org>
To: Martin Kepplinger <martin.kepplinger@puri.sm>,
	jejb@linux.ibm.com, martin.petersen@oracle.com
Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@puri.sm
Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release
Date: Wed, 24 Jun 2020 06:33:17 -0700
Message-ID: <ed9ae198-4c68-f82b-04fc-2299ab16df96@acm.org> (raw)
In-Reply-To: <20200623111018.31954-1-martin.kepplinger@puri.sm>

On 2020-06-23 04:10, Martin Kepplinger wrote:
> This add a very conservative but simple implementation for runtime PM
> to the sd scsi driver:
> Resume when opened (mounted) and suspend when released (unmounted).
> 
> Improvements that allow suspending while a device is "open" can
> be added later, but now we save power when no filesystem is mounted
> and runtime PM is enabled.
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> ---
>  drivers/scsi/sd.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index d90fefffe31b..fe4cb7c50ec1 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -1372,6 +1372,7 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
>  	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n"));
>  
>  	sdev = sdkp->device;
> +	scsi_autopm_get_device(sdev);
>  
>  	/*
>  	 * If the device is in error recovery, wait until it is done.
> @@ -1418,6 +1419,9 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
>  
>  error_out:
>  	scsi_disk_put(sdkp);
> +
> +	scsi_autopm_put_device(sdev);
> +
>  	return retval;	
>  }
>  
> @@ -1441,6 +1445,8 @@ static void sd_release(struct gendisk *disk, fmode_t mode)
>  
>  	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n"));
>  
> +	scsi_autopm_put_device(sdev);
> +
>  	if (atomic_dec_return(&sdkp->openers) == 0 && sdev->removable) {
>  		if (scsi_block_when_processing_errors(sdev))
>  			scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);

My understanding of the above patch is that it introduces a regression,
namely by disabling runtime suspend as long as an sd device is held open.

Bart.



  reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23 11:10 Martin Kepplinger
2020-06-24 13:33 ` Bart Van Assche [this message]
2020-06-25  8:16   ` Martin Kepplinger
2020-06-25 14:52     ` Alan Stern
2020-06-26  3:53     ` Bart Van Assche
2020-06-26 15:07     ` Bart Van Assche
2020-06-26 15:44       ` Alan Stern
2020-06-28  2:37         ` Bart Van Assche
2020-06-28 13:10           ` Alan Stern
2020-06-29  9:42         ` Martin Kepplinger
2020-06-29 16:15           ` Alan Stern
2020-06-29 16:56             ` Bart Van Assche
2020-06-29 17:40               ` Alan Stern
2020-06-30  3:33             ` Martin Kepplinger
2020-06-30 13:38               ` Alan Stern
2020-06-30 15:59             ` Bart Van Assche
2020-06-30 18:02               ` Alan Stern
2020-06-30 19:23                 ` Bart Van Assche
2020-06-30 19:38                   ` Alan Stern
2020-06-30 23:31                     ` Bart Van Assche
2020-07-01  0:49                       ` Alan Stern
2020-07-06 16:41                         ` Alan Stern
2020-07-28  7:02                           ` Martin Kepplinger
2020-07-28 20:02                             ` Alan Stern
2020-07-29 14:12                               ` Martin Kepplinger
2020-07-29 14:32                                 ` Alan Stern
2020-07-29 14:44                                   ` Martin K. Petersen
2020-07-29 14:56                                     ` Alan Stern
2020-07-29 14:46                                   ` James Bottomley
2020-07-29 14:53                                     ` James Bottomley
2020-07-29 15:40                                       ` Martin Kepplinger
2020-07-29 15:44                                         ` James Bottomley
2020-07-29 16:43                                           ` Martin Kepplinger
2020-07-29 18:25                                             ` Alan Stern
2020-07-29 18:29                                               ` James Bottomley
2020-07-30  8:52                                                 ` Martin Kepplinger
2020-07-30  8:54                                                   ` Martin Kepplinger
2020-07-30 15:10                                                   ` Alan Stern
2020-08-04  9:39                                                     ` Martin Kepplinger
2020-08-07  9:51                                                       ` Martin Kepplinger
2020-08-07 14:30                                                         ` Alan Stern
2020-08-08  6:59                                                           ` Martin Kepplinger
2020-08-08 15:05                                                             ` Alan Stern
2020-08-09  9:20                                                               ` Martin Kepplinger
2020-08-09 15:26                                                                 ` Alan Stern
2020-08-10 12:03                                                                   ` Martin Kepplinger
2020-08-10 14:13                                                                     ` Alan Stern
2020-08-11  7:55                                                                       ` Martin Kepplinger
2020-08-11 13:48                                                                         ` Alan Stern
2020-07-29 15:40                                       ` Alan Stern
2020-07-29 15:49                                         ` James Bottomley
2020-07-29 16:17                                           ` Alan Stern
2020-07-29 15:52                                         ` Martin Kepplinger
2020-07-29 18:10                                   ` Douglas Gilbert
2020-07-30  8:05             ` Martin Kepplinger
2020-07-30 15:14               ` Alan Stern

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