From 63787dfd1b5ae720cc30dab5e66c8e4d81ff7391 Mon Sep 17 00:00:00 2001 From: James Hilliard Date: Mon, 26 Oct 2026 12:11:31 -0600 Subject: [PATCH] ptp: vclock: preserve missing hardware timestamps 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: d7c088265588 ("net: socket: support hardware timestamp conversion to PHC bound") Reviewed-by: Vadim Fedorenko Signed-off-by: James Hilliard Link: https://patch.msgid.link/20261026-ptp-vclock-sampling-v6-5-e705612541f1@gmail.com Signed-off-by: Jakub Kicinski --- drivers/ptp/ptp_vclock.c | 2 ++ include/linux/ptp_clock_kernel.h | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c index 679ae40916f7..e9cf4da3ed8a 100644 --- a/drivers/ptp/ptp_vclock.c +++ b/drivers/ptp/ptp_vclock.c @@ -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); diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index 36a27a910595..56f6ab1855d3 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -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