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ptp: vclock: preserve missing hardware timestamps

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Socket timestamp delivery converts hardware timestamps to a bound
virtual clock before checking whether a hardware timestamp is present.
A zero timestamp means that the packet has no hardware timestamp, but
timecounter_cyc2time() can turn that zero into a nonzero virtual time.
The socket then reports a hardware timestamp which was never supplied.

Return zero without conversion when the input timestamp is absent.
This also covers skb_get_tx_timestamp(), which checks for an absent
timestamp after the same conversion.

This was identified during review of virtual clock sampling changes.

Fixes: d7c0882655 ("net: socket: support hardware timestamp conversion to PHC bound")
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Link: https://patch.msgid.link/20261026-ptp-vclock-sampling-v6-5-e705612541f1@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
James Hilliard 2026-10-26 12:11:31 -06:00 committed by Jakub Kicinski
parent d3fcce5afe
commit 63787dfd1b
2 changed files with 3 additions and 1 deletions
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2
drivers/ptp/ptp_vclock.c
View File

@ -326,6 +326,8 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index)
u64 ns;
ns = ktime_to_ns(*hwtstamp);
if (!ns)
return 0;
srcu_idx = srcu_read_lock(&vclock_srcu);

2
include/linux/ptp_clock_kernel.h
View File

@ -496,7 +496,7 @@ int ptp_get_vclocks_index(int pclock_index, int **vclock_index);
* @hwtstamp: timestamp
* @vclock_index: phc index of ptp vclock.
*
* Returns: converted timestamp, or 0 on error.
* Returns: converted timestamp, or 0 if @hwtstamp is zero or on error.
*/
ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index);
#else