Re: [PATCH] ata: libata-core: Do not call ata_dev_power_set_standby() twice

[Niklas Cassel <cassel@kernel.org>]

On Fri, Feb 16, 2024 at 09:16:23PM +0900, Damien Le Moal wrote:
> On 2/16/24 20:20, Niklas Cassel wrote:
> > From: Damien Le Moal <dlemoal@kernel.org>
> > 
> > For regular system shutdown, ata_dev_power_set_standby() will be
> > executed twice: once the scsi device is removed and another when
> > ata_pci_shutdown_one() executes and EH completes unloading the devices.
> > 
> > Make the second call to ata_dev_power_set_standby() do nothing by using
> > ata_dev_power_is_active() and return if the device is already in
> > standby.
> > 
> > Fixes: 2da4c5e24e86 ("ata: libata-core: Improve ata_dev_power_set_active()")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> > Signed-off-by: Niklas Cassel <cassel@kernel.org>
> > ---
> > This fix was originally part of patch that contained both a fix and
> > a revert in a single patch:
> > https://lore.kernel.org/linux-ide/20240111115123.1258422-3-dlemoal@kernel.org/
> > 
> > This patch contains the only the fix (as it is valid even without the
> > revert), without the revert.
> > 
> > Updated the Fixes tag to point to a more appropriate commit, since we
> > no longer revert any code.
> > 
> >  drivers/ata/libata-core.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> > index d9f80f4f70f5..af2334bc806d 100644
> > --- a/drivers/ata/libata-core.c
> > +++ b/drivers/ata/libata-core.c
> > @@ -85,6 +85,7 @@ static unsigned int ata_dev_init_params(struct ata_device *dev,
> >  static unsigned int ata_dev_set_xfermode(struct ata_device *dev);
> >  static void ata_dev_xfermask(struct ata_device *dev);
> >  static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
> > +static bool ata_dev_power_is_active(struct ata_device *dev);
> 
> I forgot what I did originally but didn't I move the code of
> ata_dev_power_is_active() before ata_dev_power_set_standby() to avoid this
> forward declaration ?
> 
> With that, the code is a little odd as ata_dev_power_is_active() is defined
> between ata_dev_power_set_standby() and ata_dev_power_set_active() but both
> functions use it...

Yes, you moved the function instead of forward declaring it.

But then there was a discussion of why ATA_TFLAG_ISADDR is set in
ata_dev_power_is_active():
https://lore.kernel.org/linux-ide/d63a7b93-d1a3-726e-355c-b4a4608626f4@gmail.com/

And you said that you were going to look in to it:
https://lore.kernel.org/linux-ide/0563322c-4093-4e7d-bb48-61712238494e@kernel.org/

Since this fix does not strictly require any changes to
ata_dev_power_is_active(), and since we already have a bunch of
forward declared functions, I think that forward declaring it is a
good way to avoid this actual fix from falling through the cracks.


Kind regards,
Niklas