Re: [PATCH iwl] ice: acquire NVM lock around each flash read

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

On 7/3/26 12:32, Robert Malz 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 would overwrite sq_last_status, so the read's AQ error is preserved
> across the release for callers such as ice_discover_flash_size() that
> inspect it.
> 
> 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 per-block locking in ice_devlink_nvm_snapshot() is now redundant
> and dropped.
> 
> Fixes: e94509906d6b ("ice: create function to read a section of the NVM and Shadow RAM")
> Signed-off-by: Robert Malz <robert.malz@canonical.com>

thank you for extra effort [1]
current fix looks elegant!
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>

[1] for reference, this is previous attempt for the fix:
https://lore.kernel.org/intel-wired-lan/CADcc-bysA531q2Wh=TD_oFqxivLLdnCRNY5jy7mkZuO0cwJwvg@mail.gmail.com

[...]

>   /**
> - * ice_read_sr_word - Reads Shadow RAM word and acquire NVM if necessary
> + * ice_read_sr_word - Reads Shadow RAM word
>    * @hw: pointer to the HW structure
>    * @offset: offset of the Shadow RAM word to read (0x000000 - 0x001FFF)
>    * @data: word read from the Shadow RAM
>    *
> - * Reads one 16 bit word from the Shadow RAM using the ice_read_sr_word_aq.
> + * Reads one 16 bit word from the Shadow RAM using ice_read_sr_word_aq.
> + *
> + * The NVM lock is acquired and released internally by ice_read_flat_nvm()
> + * around the FW read, so this function must be called without the lock held.
>    */

for future submissions would be great to "fix" kdoc warnings of touched
functions, here "Return: " section is missing.
I do not ask to fix this particular one (given there will be no ask for
v2 otherwise).

>   int ice_read_sr_word(struct ice_hw *hw, u16 offset, u16 *data)
>   {