RE: [PATCH iwl-net 09/12] ice: keep Tx timestamp slots tracked until completion or timeout

> -----Original Message-----
> From: Keller, Jacob E <[email protected]> 
> Sent: Friday, August 21, 2026 5:13 PM
> To: Intel Wired LAN <[email protected]>
> Cc: [email protected]; Machnikowski, Maciej <[email protected]>; Nguyen, Anthony L <[email protected]>; Korba, Przemyslaw <[email protected]>; Nitka, Grzegorz <[email protected]>; Oros, Petr <[email protected]>; Nowlin, Alexander <[email protected]>; Bross, Kevin <[email protected]>; Cavatur, Ranjit <[email protected]>; Keller, Jacob E <[email protected]>; Machnikowski, Maciej <[email protected]>
> Subject: [PATCH iwl-net 09/12] ice: keep Tx timestamp slots tracked until completion or timeout
> 
> From: Petr Oros <[email protected]>
> 
> When the link goes down the processing loop drops every outstanding request, and a request whose timestamp is not ready yet is freed without reading the PHY slot. The hardware completes the capture a moment later, the orphaned ready bit blocks the port interrupt until the next link-up sweep, and the freed index can meanwhile be reused by a new request whose slot the hardware then overwrites. Captured on > a reproducer as ready bits with no in_use owner right after a link bounce.
> 
> Stop dropping on link down. Mark the outstanding requests stale so their completions are read and discarded, reject new requests while the link is down, and free a not yet ready slot only after the two second timeout. This way an index is never reused while the hardware can still write it and never left untracked while a completion can still arrive.
> 
> To avoid an IRQ storm in the event that we really do have a stale packet that is not timestamped, modify ice_ptp_tx_tstamps_pending() to ignore stale timestamps when checking for whether to re-arm the IRQ from the miscellaneous thread function. Instead, only check for stale packets in the auxiliary work thread. This way we do not check in a tight loop waiting for a timestamp that may never come.
> 
> This effectively reverts commit fcc2cef37fed ("ice/ptp: fix the PTP worker retrying indefinitely if the link went down"), which tried to release an index before this 2 second wait period.
> 
> Fixes: fcc2cef37fed ("ice/ptp: fix the PTP worker retrying indefinitely if the link went down")
> Suggested-by: Jacob Keller <[email protected]>
> Signed-off-by: Petr Oros <[email protected]>
> Signed-off-by: Jacob Keller <[email protected]>
> Reviewed-by: Maciek Machnikowski <[email protected]>
> ---
>  drivers/net/ethernet/intel/ice/ice_ptp.h  |  8 ++++--  drivers/net/ethernet/intel/ice/ice_main.c |  2 +-  drivers/net/ethernet/intel/ice/ice_ptp.c  | 44 +++++++++++++++----------------
>  3 files changed, 28 insertions(+), 26 deletions(-)

Tested-by: Alexander Nowlin <[email protected]>