netdev - [PATCH net-next] mlx5_en: use read sequence for gettimex64

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Message-ID: <20241014170103.2473580-1-vadfed@meta.com>
Date: Mon, 14 Oct 2024 10:01:03 -0700
From: Vadim Fedorenko <vadfed@...a.com>
To: Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>,
        Tariq Toukan <tariqt@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Rahul Rameshbabu <rrameshbabu@...dia.com>,
        Vadim Fedorenko
	<vadim.fedorenko@...ux.dev>,
        Jakub Kicinski <kuba@...nel.org>
CC: Eric Dumazet <edumazet@...gle.com>, <netdev@...r.kernel.org>,
        "Vadim
 Fedorenko" <vadfed@...a.com>
Subject: [PATCH net-next] mlx5_en: use read sequence for gettimex64

The gettimex64() doesn't modify values in timecounter, that's why there
is no need to update sequence counter. Reduce the contention on sequence
lock for multi-thread PHC reading use-case.

Signed-off-by: Vadim Fedorenko <vadfed@...a.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
index b306ae79bf97..4822d01123b4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
@@ -402,9 +402,7 @@ static int mlx5_ptp_gettimex(struct ptp_clock_info *ptp, struct timespec64 *ts,
 			     struct ptp_system_timestamp *sts)
 {
 	struct mlx5_clock *clock = container_of(ptp, struct mlx5_clock, ptp_info);
-	struct mlx5_timer *timer = &clock->timer;
 	struct mlx5_core_dev *mdev;
-	unsigned long flags;
 	u64 cycles, ns;
 
 	mdev = container_of(clock, struct mlx5_core_dev, clock);
@@ -413,10 +411,8 @@ static int mlx5_ptp_gettimex(struct ptp_clock_info *ptp, struct timespec64 *ts,
 		goto out;
 	}
 
-	write_seqlock_irqsave(&clock->lock, flags);
 	cycles = mlx5_read_time(mdev, sts, false);
-	ns = timecounter_cyc2time(&timer->tc, cycles);
-	write_sequnlock_irqrestore(&clock->lock, flags);
+	ns = mlx5_timecounter_cyc2time(clock, cycles);
 	*ts = ns_to_timespec64(ns);
 out:
 	return 0;
-- 
2.43.5