linux-kernel - [PATCH AUTOSEL 6.14 642/642] net-sysfs: restore behavior for not running devices

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Message-Id: <20250505221419.2672473-642-sashal@kernel.org>
Date: Mon,  5 May 2025 18:14:18 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>,
	Marco Leogrande <leogrande@...gle.com>,
	Antoine Tenart <atenart@...nel.org>,
	Jakub Kicinski <kuba@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	davem@...emloft.net,
	pabeni@...hat.com,
	sdf@...ichev.me,
	jdamato@...tly.com,
	aleksander.lobakin@...el.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.14 642/642] net-sysfs: restore behavior for not running devices

From: Eric Dumazet <edumazet@...gle.com>

[ Upstream commit 75bc3dab4e49b4daccb27ad6ce8ce2fcd253fc1b ]

modprobe dummy dumdummies=1

Old behavior :

$ cat /sys/class/net/dummy0/carrier
cat: /sys/class/net/dummy0/carrier: Invalid argument

After blamed commit, an empty string is reported.

$ cat /sys/class/net/dummy0/carrier
$

In this commit, I restore the old behavior for carrier,
speed and duplex attributes.

Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: Marco Leogrande <leogrande@...gle.com>
Reviewed-by: Antoine Tenart <atenart@...nel.org>
Link: https://patch.msgid.link/20250221051223.576726-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/core/net-sysfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index cedbe7d9ae670..474824e88959f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -313,12 +313,13 @@ static ssize_t carrier_show(struct device *dev,
 			    struct device_attribute *attr, char *buf)
 {
 	struct net_device *netdev = to_net_dev(dev);
-	int ret = -EINVAL;
+	int ret;
 
 	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
 	if (ret)
 		return ret;
 
+	ret = -EINVAL;
 	if (netif_running(netdev)) {
 		/* Synchronize carrier state with link watch,
 		 * see also rtnl_getlink().
@@ -349,6 +350,7 @@ static ssize_t speed_show(struct device *dev,
 	if (ret)
 		return ret;
 
+	ret = -EINVAL;
 	if (netif_running(netdev)) {
 		struct ethtool_link_ksettings cmd;
 
@@ -376,6 +378,7 @@ static ssize_t duplex_show(struct device *dev,
 	if (ret)
 		return ret;
 
+	ret = -EINVAL;
 	if (netif_running(netdev)) {
 		struct ethtool_link_ksettings cmd;
 
-- 
2.39.5