[PATCH net] net: stmmac: initialize ptp_lock at probe time

[PATCH net] net: stmmac: initialize ptp_lock at probe time

[Lorenzo Bianconi]

priv->ptp_lock is only initialized in stmmac_ptp_register(), which runs
during __stmmac_open(). However, the lock is also used while the
interface is down and has never been opened: tc_taprio_configure()
invokes the PTP gettime64() callback to compute the EST base time when
offloading a TAPRIO schedule, and stmmac_get_time() takes
priv->ptp_lock. Using an uninitialized rwlock is undefined behaviour.
Move the rwlock_init() to __stmmac_dvr_probe(), together with the other
private locks, so that ptp_lock is always valid regardless of the
interface state.

Fixes: b60189e0392f ("net: stmmac: Integrate EST with TAPRIO scheduler API")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 +
 drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c  | 1 -
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 24656b35350b..5fe7e95fdd34 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -8025,6 +8025,7 @@ static int __stmmac_dvr_probe(struct device *device,
 	stmmac_napi_add(ndev);
 
 	mutex_init(&priv->lock);
+	rwlock_init(&priv->ptp_lock);
 
 	stmmac_fpe_init(priv);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index 960249960004..3bfcc9760dce 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -365,7 +365,6 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
 	if (priv->plat->crosststamp)
 		priv->ptp_clock_ops.getcrosststamp = stmmac_getcrosststamp;
 
-	rwlock_init(&priv->ptp_lock);
 	mutex_init(&priv->aux_ts_lock);
 
 	priv->ptp_clock = ptp_clock_register(&priv->ptp_clock_ops,

---
base-commit: 641d03105cc0d2437e32fdeec164f91a4ccef6c4
change-id: 20260904-stmmac-fix-ptp-clock-init-b8eba4328243

Best regards,
-- 
Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

Re: [PATCH net] net: stmmac: initialize ptp_lock at probe time

[Maxime Chevallier]

Hi,

On 9/4/26 12:32, Lorenzo Bianconi wrote:
> priv->ptp_lock is only initialized in stmmac_ptp_register(), which runs
> during __stmmac_open(). However, the lock is also used while the
> interface is down and has never been opened: tc_taprio_configure()
> invokes the PTP gettime64() callback to compute the EST base time when
> offloading a TAPRIO schedule, and stmmac_get_time() takes
> priv->ptp_lock. Using an uninitialized rwlock is undefined behaviour.
> Move the rwlock_init() to __stmmac_dvr_probe(), together with the other
> private locks, so that ptp_lock is always valid regardless of the
> interface state.
> 
> Fixes: b60189e0392f ("net: stmmac: Integrate EST with TAPRIO scheduler API")
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 +
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c  | 1 -
>  2 files changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 24656b35350b..5fe7e95fdd34 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -8025,6 +8025,7 @@ static int __stmmac_dvr_probe(struct device *device,
>  	stmmac_napi_add(ndev);
>  
>  	mutex_init(&priv->lock);
> +	rwlock_init(&priv->ptp_lock);
>  
>  	stmmac_fpe_init(priv);
>  
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> index 960249960004..3bfcc9760dce 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> @@ -365,7 +365,6 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
>  	if (priv->plat->crosststamp)
>  		priv->ptp_clock_ops.getcrosststamp = stmmac_getcrosststamp;
>  
> -	rwlock_init(&priv->ptp_lock);
>  	mutex_init(&priv->aux_ts_lock);
>  
>  	priv->ptp_clock = ptp_clock_register(&priv->ptp_clock_ops,
> 
> ---
> base-commit: 641d03105cc0d2437e32fdeec164f91a4ccef6c4
> change-id: 20260904-stmmac-fix-ptp-clock-init-b8eba4328243
> 
> Best regards,