Re: [PATCH] ata: libata-sata: fix ata_scsi_lpm_supported() iteration

Thank you for your contribution! Sashiko AI review found 1 potential issue(=
s) to consider:

Pre-existing issues:
- [High] ata_scsi_lpm_supported() skips checking devices on the slave link =
because it uses the ATA_LITER_EDGE iterator. This allows userspace to enabl=
e Link Power Management (LPM) on a port where the slave device does not sup=
port it (has ATA_QUIRK_NOLPM).
--

--- Patch [1]: [PATCH] ata: libata-sata: fix ata_scsi_lpm_supported() itera=
tion ---
commit 32bd728de2e1b6025504205f3ade16813231e703
Author: Niklas Cassel <[email protected]>

ata: libata-sata: fix ata_scsi_lpm_supported() iteration

This commit fixes the inner loop of ata_scsi_lpm_supported() to iterate
over the specific link being evaluated rather than always using the host
link. This prevents the LPM policy from being incorrectly applied or denied.

Link: https://lore.kernel.org/linux-ide/[email protected]=
rnel.org/

> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index b0706c30da052..ad40f516c6d43 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -913,7 +913,7 @@ static bool ata_scsi_lpm_supported(struct ata_port *a=
p)
>  		return false;
> =20
>  	ata_for_each_link(link, ap, EDGE) {
> -		ata_for_each_dev(dev, &ap->link, ENABLED) {
> +		ata_for_each_dev(dev, link, ENABLED) {

[Severity: High]
This is a pre-existing issue, but does using the ATA_LITER_EDGE iterator
here in ata_scsi_lpm_supported() skip checking devices on the slave link?

Since the EDGE iterator skips ap->slave_link, it appears this loop misses
devices on the slave link that might have the ATA_QUIRK_NOLPM quirk.=20

If a user or power-management tool writes to the sysfs attribute
link_power_management_policy, ata_scsi_lpm_supported() would incorrectly
return true. Then ata_port_schedule_eh() triggers Error Handling, and
ata_eh_link_set_lpm() might blindly apply the unsupported policy to the
slave link.=20

Can this result in the slave drive becoming unresponsive, leading to
command timeouts or dropped devices?

>  			if (dev->quirks & ATA_QUIRK_NOLPM)
>  				return false;
>  		}

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260728113841.7272=
[email protected]?part=3D1