Subject: [RFC PATCH v3 2/5] Add ifreq pointer field to kernel_hwtstamp_config structure

From: Maxim Georgiev <[email-masked]>
Date: Wed, 5 Apr 2023 00:33:06 -0600

Considering the stackable nature of drivers there will be situations
where a driver implementing ndo_hwtstamp_get/set functions will have
to translate requests back to SIOCGHWTSTAMP/SIOCSHWTSTAMP IOCTLs
to pass them to lower level drivers that do not provide
ndo_hwtstamp_get/set callbacks. To simplify request translation in
such scenarios let's include a pointer to the original struct ifreq
to kernel_hwtstamp_config structure.

Suggested-by: Jakub Kicinski <[email-masked]>
Signed-off-by: Maxim Georgiev <[email-masked]>
---
 include/linux/net_tstamp.h | 1 +
 net/core/dev_ioctl.c       | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/net_tstamp.h b/include/linux/net_tstamp.h
index 063260475e77..bbb41f4fe985 100644
--- a/include/linux/net_tstamp.h
+++ b/include/linux/net_tstamp.h
@@ -20,6 +20,7 @@ struct kernel_hwtstamp_config {
 	int flags;
 	int tx_type;
 	int rx_filter;
+	struct ifreq *ifr;
 };
 
 static inline void hwtstamp_config_to_kernel(struct kernel_hwtstamp_config *kernel_cfg,
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 736f310a0661..043f4363c98f 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -255,7 +255,7 @@ static int dev_eth_ioctl(struct net_device *dev,
 static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
-	struct kernel_hwtstamp_config kernel_cfg;
+	struct kernel_hwtstamp_config kernel_cfg = {};
 	struct hwtstamp_config config;
 	int err;
 
@@ -265,6 +265,7 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 	if (!netif_device_present(dev))
 		return -ENODEV;
 
+	kernel_cfg.ifr = ifr;
 	err = ops->ndo_hwtstamp_get(dev, &kernel_cfg, NULL);
 	if (err)
 		return err;
@@ -281,7 +282,7 @@ static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 	struct netdev_notifier_hwtstamp_info info = {
 		.info.dev = dev,
 	};
-	struct kernel_hwtstamp_config kernel_cfg;
+	struct kernel_hwtstamp_config kernel_cfg = {};
 	struct netlink_ext_ack extack = {};
 	struct hwtstamp_config cfg;
 	int err;
@@ -290,6 +291,7 @@ static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 		return -EFAULT;
 
 	hwtstamp_config_to_kernel(&kernel_cfg, &cfg);
+	kernel_cfg.ifr = ifr;
 
 	err = net_hwtstamp_validate(&kernel_cfg);
 	if (err)
-- 
2.39.2