[PATCH v2 net] net: dev_ioctl: take ops lock in hwtstamp lower paths

[PATCH v2 net] net: dev_ioctl: take ops lock in hwtstamp lower paths

[Carolina Jubran]

ndo hwtstamp callbacks are expected to run under the per-device ops
lock. Make the lower get/set paths consistent with the rest of ndo
invocations.

Kernel log:
WARNING: CPU: 13 PID: 51364 at ./include/net/netdev_lock.h:70 __netdev_update_features+0x4bd/0xe60
...
RIP: 0010:__netdev_update_features+0x4bd/0xe60
...
Call Trace:
<TASK>
netdev_update_features+0x1f/0x60
mlx5_hwtstamp_set+0x181/0x290 [mlx5_core]
mlx5e_hwtstamp_set+0x19/0x30 [mlx5_core]
dev_set_hwtstamp_phylib+0x9f/0x220
dev_set_hwtstamp_phylib+0x9f/0x220
dev_set_hwtstamp+0x13d/0x240
dev_ioctl+0x12f/0x4b0
sock_ioctl+0x171/0x370
__x64_sys_ioctl+0x3f7/0x900
? __sys_setsockopt+0x69/0xb0
do_syscall_64+0x6f/0x2e0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
...
</TASK>
....
---[ end trace 0000000000000000 ]---

Note that the mlx5_hwtstamp_set and mlx5e_hwtstamp_set functions shown
in the trace come from an in progress patch converting the legacy ioctl
to ndo_hwtstamp_get/set and are not present in mainline.

Fixes: ffb7ed19ac0a ("net: hold netdev instance lock during ioctl operations")
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>

---
 V2:
  - Clarify in the commit message that mlx5 functions from the trace
    are not present in mainline.
  - Link to V1: https://lore.kernel.org/netdev/20250904182806.2329996-1-cjubran@nvidia.com/
---
 net/core/dev_ioctl.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 9c0ad7f4b5d8..ad54b12d4b4c 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -464,8 +464,15 @@ int generic_hwtstamp_get_lower(struct net_device *dev,
 	if (!netif_device_present(dev))
 		return -ENODEV;
 
-	if (ops->ndo_hwtstamp_get)
-		return dev_get_hwtstamp_phylib(dev, kernel_cfg);
+	if (ops->ndo_hwtstamp_get) {
+		int err;
+
+		netdev_lock_ops(dev);
+		err = dev_get_hwtstamp_phylib(dev, kernel_cfg);
+		netdev_unlock_ops(dev);
+
+		return err;
+	}
 
 	/* Legacy path: unconverted lower driver */
 	return generic_hwtstamp_ioctl_lower(dev, SIOCGHWTSTAMP, kernel_cfg);
@@ -481,8 +488,15 @@ int generic_hwtstamp_set_lower(struct net_device *dev,
 	if (!netif_device_present(dev))
 		return -ENODEV;
 
-	if (ops->ndo_hwtstamp_set)
-		return dev_set_hwtstamp_phylib(dev, kernel_cfg, extack);
+	if (ops->ndo_hwtstamp_set) {
+		int err;
+
+		netdev_lock_ops(dev);
+		err = dev_set_hwtstamp_phylib(dev, kernel_cfg, extack);
+		netdev_unlock_ops(dev);
+
+		return err;
+	}
 
 	/* Legacy path: unconverted lower driver */
 	return generic_hwtstamp_ioctl_lower(dev, SIOCSHWTSTAMP, kernel_cfg);
-- 
2.38.1

Re: [PATCH v2 net] net: dev_ioctl: take ops lock in hwtstamp lower paths

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sun, 7 Sep 2025 11:08:21 +0300 you wrote:
> ndo hwtstamp callbacks are expected to run under the per-device ops
> lock. Make the lower get/set paths consistent with the rest of ndo
> invocations.
> 
> Kernel log:
> WARNING: CPU: 13 PID: 51364 at ./include/net/netdev_lock.h:70 __netdev_update_features+0x4bd/0xe60
> ...
> RIP: 0010:__netdev_update_features+0x4bd/0xe60
> ...
> Call Trace:
> <TASK>
> netdev_update_features+0x1f/0x60
> mlx5_hwtstamp_set+0x181/0x290 [mlx5_core]
> mlx5e_hwtstamp_set+0x19/0x30 [mlx5_core]
> dev_set_hwtstamp_phylib+0x9f/0x220
> dev_set_hwtstamp_phylib+0x9f/0x220
> dev_set_hwtstamp+0x13d/0x240
> dev_ioctl+0x12f/0x4b0
> sock_ioctl+0x171/0x370
> __x64_sys_ioctl+0x3f7/0x900
> ? __sys_setsockopt+0x69/0xb0
> do_syscall_64+0x6f/0x2e0
> entry_SYSCALL_64_after_hwframe+0x4b/0x53
> ...
> </TASK>
> ....
> 
> [...]

Here is the summary with links:
  - [v2,net] net: dev_ioctl: take ops lock in hwtstamp lower paths
    https://git.kernel.org/netdev/net/c/686cab5a18e4

You are awesome, thank you!
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