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net: dsa: remove redundant netdev_lock_ops() from conduit ethtool ops 

DSA replaces the conduit (master) device's ethtool_ops with its own
wrappers that aggregate stats from both the conduit and DSA switch
ports. Taking the lock again inside the DSA wrappers causes a deadlock.

Stumbled upon this when booting qemu with fbnic and CONFIG_NET_DSA_LOOP=y
(which looks like some kind of testing device that auto-populates the ports
of eth0). `ethtool -i` is enough to deadlock. This means we have basically zero
coverage for DSA stuff with real ops locked devs.

Remove the redundant netdev_lock_ops()/netdev_unlock_ops() calls from
the DSA conduit ethtool wrappers.

Fixes: 2bcf4772e4 ("net: ethtool: try to protect all callback with netdev instance lock")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260414231035.1917035-1-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Stanislav Fomichev 2026-04-14 16:10:35 -07:00 committed by Jakub Kicinski
parent 105425b196
commit 0f99e0c3e1
1 changed files with 1 additions and 15 deletions
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16
net/dsa/conduit.c
View File

@ -27,9 +27,7 @@ static int dsa_conduit_get_regs_len(struct net_device *dev)
int len;
if (ops && ops->get_regs_len) {
netdev_lock_ops(dev);
len = ops->get_regs_len(dev);
netdev_unlock_ops(dev);
if (len < 0)
return len;
ret += len;
@ -60,15 +58,11 @@ static void dsa_conduit_get_regs(struct net_device *dev,
int len;
if (ops && ops->get_regs_len && ops->get_regs) {
netdev_lock_ops(dev);
len = ops->get_regs_len(dev);
if (len < 0) {
netdev_unlock_ops(dev);
if (len < 0)
return;
}
regs->len = len;
ops->get_regs(dev, regs, data);
netdev_unlock_ops(dev);
data += regs->len;
}
@ -115,10 +109,8 @@ static void dsa_conduit_get_ethtool_stats(struct net_device *dev,
int count, mcount = 0;
if (ops && ops->get_sset_count && ops->get_ethtool_stats) {
netdev_lock_ops(dev);
mcount = ops->get_sset_count(dev, ETH_SS_STATS);
ops->get_ethtool_stats(dev, stats, data);
netdev_unlock_ops(dev);
}
list_for_each_entry(dp, &dst->ports, list) {
@ -149,10 +141,8 @@ static void dsa_conduit_get_ethtool_phy_stats(struct net_device *dev,
if (count >= 0)
phy_ethtool_get_stats(dev->phydev, stats, data);
} else if (ops && ops->get_sset_count && ops->get_ethtool_phy_stats) {
netdev_lock_ops(dev);
count = ops->get_sset_count(dev, ETH_SS_PHY_STATS);
ops->get_ethtool_phy_stats(dev, stats, data);
netdev_unlock_ops(dev);
}
if (count < 0)
@ -176,13 +166,11 @@ static int dsa_conduit_get_sset_count(struct net_device *dev, int sset)
struct dsa_switch_tree *dst = cpu_dp->dst;
int count = 0;
netdev_lock_ops(dev);
if (sset == ETH_SS_PHY_STATS && dev->phydev &&
(!ops || !ops->get_ethtool_phy_stats))
count = phy_ethtool_get_sset_count(dev->phydev);
else if (ops && ops->get_sset_count)
count = ops->get_sset_count(dev, sset);
netdev_unlock_ops(dev);
if (count < 0)
count = 0;
@ -239,7 +227,6 @@ static void dsa_conduit_get_strings(struct net_device *dev, u32 stringset,
struct dsa_switch_tree *dst = cpu_dp->dst;
int count, mcount = 0;
netdev_lock_ops(dev);
if (stringset == ETH_SS_PHY_STATS && dev->phydev &&
!ops->get_ethtool_phy_stats) {
mcount = phy_ethtool_get_sset_count(dev->phydev);
@ -253,7 +240,6 @@ static void dsa_conduit_get_strings(struct net_device *dev, u32 stringset,
mcount = 0;
ops->get_strings(dev, stringset, data);
}
netdev_unlock_ops(dev);
list_for_each_entry(dp, &dst->ports, list) {
if (!dsa_port_is_dsa(dp) && !dsa_port_is_cpu(dp))