Re: [PATCH net v4 0/2] net: ravb: fix PTP clock lifetime

Hi Xuanqiang,

Thanks for your work.

On 2026-08-11 18:37:31 +0800, Xuanqiang Luo wrote:
> From: Xuanqiang Luo <[email protected]>
> 
> This series fixes RAVB PTP clock lifetime handling. It reports a cached PHC
> index without accessing the clock pointer and drains PTP interrupts before
> unregistering the clock.
> 
> Patch 1 caches the PHC index and handles registration failures.
> 
> Patch 2 detaches the clock with xchg() and drains the PTP IRQs before
> unregistering it.

These patches are rather big change adding READ_ONCE() and WRITE_ONCE() 
to avoid a LLM warning? Or have you hit a real issue? How have you 
tested this work?

If you have a test-case could you share it? I have a pending series [1] 
that cleans up the whole RAVB driver ptp management which have grown 
rather organically. It have a small fix for the missing check of 
registering the clock. Would it be possible for you to test your work 
with that series too?

1.  https://lore.kernel.org/all/20260811160200.2049987-1-niklas.soderlund%[email protected]/

> 
> ---
> Changes:
> v4:
>   - Rebase onto Linux 7.2-rc7.
>   Patch 1:
>   - Cache the PHC index separately instead of locking clock access.
>     (Vadim Fedorenko)
>   - Reword the subject and update the commit message for the cached PHC
>     index approach.
>   - Add Vadim Fedorenko's Reviewed-by tag.
>   Patch 2:
>   - Replace priv->lock serialization with PTP interrupt disabling and IRQ
>     draining before unregistering the clock. (Vadim Fedorenko)
>   - Use READ_ONCE() and WRITE_ONCE() for lockless clock pointer access and
>     xchg() to detach the clock atomically.
>   - Track the error and management IRQs and synchronize all IRQs that can
>     invoke the PTP handler.
>   - Update the commit message to describe the interrupt handler race and
>     the new teardown sequence.
> 
> v3: https://lore.kernel.org/all/[email protected]/
>   Patch 1:
>   - Omit Niklas Söderlund's Reviewed-by tag because the implementation he
>     reviewed has changed.
>   - Describe the NULL pointer dereference before the first open as the most
>     likely failure mode in the commit message. (Jakub Kicinski, Sashiko)
>   - Normalize PTP clock registration failures to NULL.
>     (Jakub Kicinski, Sashiko)
>   - Keep hardware timestamping capabilities independent of PHC
>     availability. (Jakub Kicinski, Sashiko)
>   Patch 2 (new):
>   - Serialize PTP clock publication and access with priv->lock, and detach
>     the clock before unregistering it. (Jakub Kicinski, Sashiko)
> 
> v2: https://lore.kernel.org/all/[email protected]/
>   - Only advertise hardware timestamping support when a PHC is available
>     (Niklas Söderlund).
> 
> v1: https://lore.kernel.org/all/[email protected]/
> 
> Xuanqiang Luo (2):
>   net: ravb: avoid dereferencing an invalid PTP clock
>   net: ravb: serialize PTP clock teardown
> 
>  drivers/net/ethernet/renesas/ravb.h      |  3 ++
>  drivers/net/ethernet/renesas/ravb_main.c |  9 +++--
>  drivers/net/ethernet/renesas/ravb_ptp.c  | 44 ++++++++++++++++++++----
>  3 files changed, 47 insertions(+), 9 deletions(-)
> 
> 
> base-commit: db2ddb87143519e20a95aa36c60b36107b736a58
> -- 
> 2.43.0

-- 
Kind Regards,
Niklas Söderlund