[PATCH net-next v2 2/3] gve: make nic clock reads thread safe
From: Harshitha Ramamurthy <hramamurthy@google.com>
Date: 2026-03-26 22:45:35
Also in:
lkml
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Ankit Garg <redacted> Add a mutex to protect the shared DMA buffer that receives NIC timestamp reports. The NIC timestamp will be read from two different threads: the periodic worker and upcoming `gettimex64`. Reviewed-by: Joshua Washington <joshwash@google.com> Signed-off-by: Ankit Garg <redacted> Signed-off-by: Jordan Rhee <redacted> Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com> --- drivers/net/ethernet/google/gve/gve.h | 6 +---- drivers/net/ethernet/google/gve/gve_ptp.c | 32 +++++++++++++++-------- 2 files changed, 22 insertions(+), 16 deletions(-)
diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 1d66d3834f7e..7b8f78bd1968 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h@@ -923,6 +923,7 @@ struct gve_priv { bool nic_timestamp_supported; struct gve_ptp *ptp; struct kernel_hwtstamp_config ts_config; + struct mutex nic_ts_read_lock; /* Protects nic_ts_report */ struct gve_nic_ts_report *nic_ts_report; dma_addr_t nic_ts_report_bus; u64 last_sync_nic_counter; /* Clock counter from last NIC TS report */
@@ -1321,14 +1322,9 @@ int gve_flow_rules_reset(struct gve_priv *priv); int gve_init_rss_config(struct gve_priv *priv, u16 num_queues); /* PTP and timestamping */ #if IS_ENABLED(CONFIG_PTP_1588_CLOCK) -int gve_clock_nic_ts_read(struct gve_priv *priv); int gve_init_clock(struct gve_priv *priv); void gve_teardown_clock(struct gve_priv *priv); #else /* CONFIG_PTP_1588_CLOCK */ -static inline int gve_clock_nic_ts_read(struct gve_priv *priv) -{ - return -EOPNOTSUPP; -} static inline int gve_init_clock(struct gve_priv *priv) {
diff --git a/drivers/net/ethernet/google/gve/gve_ptp.c b/drivers/net/ethernet/google/gve/gve_ptp.c
index 06b1cf4a5efc..140b8fbce4f4 100644
--- a/drivers/net/ethernet/google/gve/gve_ptp.c
+++ b/drivers/net/ethernet/google/gve/gve_ptp.c@@ -11,19 +11,20 @@ #define GVE_NIC_TS_SYNC_INTERVAL_MS 250 /* Read the nic timestamp from hardware via the admin queue. */ -int gve_clock_nic_ts_read(struct gve_priv *priv) +static int gve_clock_nic_ts_read(struct gve_priv *priv, u64 *nic_raw) { - u64 nic_raw; int err; + mutex_lock(&priv->nic_ts_read_lock); err = gve_adminq_report_nic_ts(priv, priv->nic_ts_report_bus); if (err) - return err; + goto out; - nic_raw = be64_to_cpu(priv->nic_ts_report->nic_timestamp); - WRITE_ONCE(priv->last_sync_nic_counter, nic_raw); + *nic_raw = be64_to_cpu(priv->nic_ts_report->nic_timestamp); - return 0; +out: + mutex_unlock(&priv->nic_ts_read_lock); + return err; } static int gve_ptp_gettimex64(struct ptp_clock_info *info,
@@ -43,15 +44,19 @@ static long gve_ptp_do_aux_work(struct ptp_clock_info *info) { const struct gve_ptp *ptp = container_of(info, struct gve_ptp, info); struct gve_priv *priv = ptp->priv; + u64 nic_raw; int err; if (gve_get_reset_in_progress(priv) || !gve_get_admin_queue_ok(priv)) goto out; - err = gve_clock_nic_ts_read(priv); - if (err && net_ratelimit()) - dev_err(&priv->pdev->dev, - "%s read err %d\n", __func__, err); + err = gve_clock_nic_ts_read(priv, &nic_raw); + if (err) { + dev_err_ratelimited(&priv->pdev->dev, "%s read err %d\n", + __func__, err); + goto out; + } + WRITE_ONCE(priv->last_sync_nic_counter, nic_raw); out: return msecs_to_jiffies(GVE_NIC_TS_SYNC_INTERVAL_MS);
@@ -109,6 +114,7 @@ static void gve_ptp_release(struct gve_priv *priv) int gve_init_clock(struct gve_priv *priv) { + u64 nic_raw; int err; err = gve_ptp_init(priv);
@@ -125,17 +131,20 @@ int gve_init_clock(struct gve_priv *priv) err = -ENOMEM; goto release_ptp; } - err = gve_clock_nic_ts_read(priv); + mutex_init(&priv->nic_ts_read_lock); + err = gve_clock_nic_ts_read(priv, &nic_raw); if (err) { dev_err(&priv->pdev->dev, "failed to read NIC clock %d\n", err); goto release_nic_ts_report; } + WRITE_ONCE(priv->last_sync_nic_counter, nic_raw); ptp_schedule_worker(priv->ptp->clock, msecs_to_jiffies(GVE_NIC_TS_SYNC_INTERVAL_MS)); return 0; release_nic_ts_report: + mutex_destroy(&priv->nic_ts_read_lock); dma_free_coherent(&priv->pdev->dev, sizeof(struct gve_nic_ts_report), priv->nic_ts_report, priv->nic_ts_report_bus);
@@ -150,6 +159,7 @@ void gve_teardown_clock(struct gve_priv *priv) gve_ptp_release(priv); if (priv->nic_ts_report) { + mutex_destroy(&priv->nic_ts_read_lock); dma_free_coherent(&priv->pdev->dev, sizeof(struct gve_nic_ts_report), priv->nic_ts_report, priv->nic_ts_report_bus);
--
2.53.0.1018.g2bb0e51243-goog