Re: [Intel-wired-lan] [PATCH iwl v4] ice: acquire NVM lock around each flash read

[Przemek Kitszel]

On 8/4/26 10:35, Robert Malz via Intel-wired-lan wrote:
> FW caps the NVM read lock at a maximum of 3000ms regardless of the timeout
> requested via ice_acquire_nvm(). ice_read_flat_nvm() splits a read into
> multiple ice_aq_read_nvm() commands, one per 4KB sector, all issued under a
> single lock taken by the caller. Reading a large region can exceed 3000ms,
> so FW reclaims the lock mid-read and the remaining commands might fail.
>
> Move the lock acquire/release into ice_read_flat_nvm() so it brackets each
> individual ice_aq_read_nvm() command, ensuring the lock is never held
> across more than one FW read.
>
> ice_release_nvm() issues its own AQ command and overwrites
> hw->adminq.sq_last_status, which some callers inspect after a failed read.
> Add an optional read_aq_err output parameter to ice_read_flat_nvm() to
> capture the failing read's AQ error before the release; callers that need
> it (ice_discover_flash_size() and the ethtool/devlink log paths) use it
> instead of sq_last_status, others pass NULL.
>
> Callers that previously took the lock around ice_read_flat_nvm(),
> ice_read_sr_word() or ice_read_flash_module() now call them without it.
> The now-redundant per-block locking in ice_devlink_nvm_snapshot() is
> dropped. ice_read_sr_word() is now a thin wrapper, so ice_read_sr_word_aq()
> is folded into it.
>
> Fixes: e94509906d6b ("ice: create function to read a section of the NVM and Shadow RAM")
> Signed-off-by: Robert Malz <robert.malz@xxxxxxxxxxxxx>
> ---
> v4:
> - Fold ice_read_sr_word_aq() into ice_read_sr_word() now that the latter is
>    only a wrapper.
> - Reduce the scope of read_aq_err in ice_devlink_nvm_snapshot() to the read
>    loop.
> - Fix reverse christmas tree ordering of the added read_aq_err declarations.
> v3:
> - Log the failure via ice_debug() when ice_acquire_nvm() fails inside
>    ice_read_flat_nvm(), rather than silently aborting the read.
> v2:
> - Replace the save/restore of sq_last_status across ice_release_nvm(),
>    which could race with a concurrent AdminQ command, with a new optional
>    read_aq_err output parameter.
> - Add missing "Return:" kdoc to ice_read_sr_word().
> ---

very nice, thank you for making the needed changes to have cleaner API

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@xxxxxxxxx>