linux-kernel - Re: [PATCH] scsi: sd: fix sd shutdown to issue START STOP UNIT command appropriately

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Message-ID: <CAPE3x153br+UdtWYnxdtAX7hz2OwKYovQeWdeOCWvicTxDayeQ@mail.gmail.com>
Date: Thu, 24 Jul 2025 14:05:05 -0700
From: Salomon Dushimirimana <salomondush@...gle.com>
To: Bart Van Assche <bvanassche@....org>
Cc: "James E . J . Bottomley" <James.Bottomley@...senpartnership.com>, 
	"Martin K . Petersen" <martin.petersen@...cle.com>, linux-scsi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Vishakha Channapattan <vishakhavc@...gle.com>, 
	Igor Pylypiv <ipylypiv@...gle.com>
Subject: Re: [PATCH] scsi: sd: fix sd shutdown to issue START STOP UNIT
 command appropriately

Hi Bart,

Thanks for the timely feedback! I also thought that the
manage_system_start_stop flag is more appropriate.

But I wasn't sure why the commit mentioned in the description removed
the manage_system_start_stop from ata_scsi_dev_config() function in
the first place. So other candidates for a fix were:
1. Adding the setting of the manage_system_start_stop flag back to
ata_scsi_dev_config()
2. Configuring our various drivers to individually enable the
manage_system_start_stop flag (less preferable)

If there was no good reason to remove setting the flag, we can go with
option 1.

Thanks,

On Thu, Jul 24, 2025 at 1:46 PM Bart Van Assche <bvanassche@....org> wrote:
>
> On 7/24/25 1:38 PM, Salomon Dushimirimana wrote:
> > Commit aa3998dbeb3a ("ata: libata-scsi: Disable scsi device
> > manage_system_start_stop") enabled libata EH to manage device power mode
> > trasitions for system suspend/resume and removed the flag from
> > ata_scsi_dev_config. However, since the sd_shutdown() function still
> > relies on the manage_system_start_stop flag, a spin-down command is not
> > issued to the disk with command "echo 1 > /sys/block/sdb/device/delete"
> >
> > sd_shutdown() can be called for both system/runtime start stop
> > operations, so utilize the manage_run_time_start_stop flag set in the
> > ata_scsi_dev_config and issue a spin-down command during disk removal
> > when the system is running. This is in addition to when the system is
> > powering off and manage_shutdown flag is set. The
> > manage_system_start_stop flag will still be used for drivers that still
> > set the flag.
> >
> > Signed-off-by: Salomon Dushimirimana <salomondush@...gle.com>
> > ---
> >   drivers/scsi/sd.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> > index eeaa6af294b81..282000c761f8e 100644
> > --- a/drivers/scsi/sd.c
> > +++ b/drivers/scsi/sd.c
> > @@ -4173,7 +4173,9 @@ static void sd_shutdown(struct device *dev)
> >       if ((system_state != SYSTEM_RESTART &&
> >            sdkp->device->manage_system_start_stop) ||
> >           (system_state == SYSTEM_POWER_OFF &&
> > -          sdkp->device->manage_shutdown)) {
> > +          sdkp->device->manage_shutdown) ||
> > +         (system_state == SYSTEM_RUNNING &&
> > +          sdkp->device->manage_runtime_start_stop)) {
> >               sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
> >               sd_start_stop_device(sdkp, 0);
> >       }
>
> A Fixes: tag is missing.
>
> manage_runtime_start_stop is for runtime power management.
> /sys/block/*/device/delete is not related to runtime power management.
> Isn't manage_system_start_stop more appropriate here than
> manage_runtime_start_stop? Shouldn't sd_shutdown() calls triggered by
> writing into /sys/block/*/device/delete already be covered by this
> test: system_state != SYSTEM_RESTART &&
>    sdkp->device->manage_system_start_stop?
>
> Thanks,
>
> Bart.