Re: [PATCH] hwmon: (pmbus/adm1266) serialize firmware_revision debugfs read with pmbus_lock

[Guenter Roeck]

On Wed, May 20, 2026 at 10:38:28AM -0700, Abdurrahman Hussain wrote:
> adm1266_firmware_revision_read() backs the firmware_revision debugfs
> entry and issues an i2c_smbus_read_block_data(client,
> ADM1266_IC_DEVICE_REV, buf) without taking pmbus_lock.  pmbus_core
> holds pmbus_lock around its own multi-transaction sequences
> (notably the "set PAGE, then read paged register" pattern used by
> hwmon attributes), so an unlocked debugfs reader can land between
> a PAGE write and the subsequent paged read in another thread.
> IC_DEVICE_REV itself is not paged, so it cannot corrupt PAGE in
> flight, but the same defensive serialisation applied to the other
> adm1266 direct-device accessors applies here: any direct device
> access from outside pmbus_core should be ordered with respect to
> pmbus_core's own.
> 
> Take pmbus_lock at the top of adm1266_firmware_revision_read()
> via the scope-based guard(), matching the pattern just applied to
> adm1266_state_read() and the GPIO/NVMEM accessors.
> 
> Fixes: 7c99762af5c1 ("hwmon: (pmbus/adm1266) add firmware_revision debugfs entry")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
> Assisted-by: Claude-Code:claude-opus-4-7
> ---
> The previous "GPIO, NVMEM, and debugfs accessor fixes" series [1]
> locked all the adm1266 direct-device accessors except this one,
> which slipped through because firmware_revision was already in
> hwmon-next when the fixes were written.  Same defensive-locking
> reason as adm1266_state_read() got there; same Fixes: shape
> (stable backport candidate against the original firmware_revision
> patch).

I completely forgot about this one. Thanks for remembering.
I squashed this patch into the firmware_revision patch.

Thanks!

Guenter