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net: bridge: don't recurse on the port's netdev ops lock

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port_cost() calls __ethtool_get_link_ksettings() on the port device,
which will soon take the port's ops lock. br_port_carrier_check()
is reached via the NETDEV_CHANGE notifier from linkwatch, which
already holds the port's ops lock, so the call would deadlock.

Make port_cost() expect the port's ops lock held and switch to
netif_get_link_ksettings(). The only other caller is new_nbp(),
make sure it takes the lock explicitly.

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260603012840.2254293-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2026-06-02 18:28:36 -07:00
parent a6882c1583
commit 20398c41d0
1 changed files with 5 additions and 2 deletions
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7
net/bridge/br_if.c
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@ -19,6 +19,7 @@
#include <linux/if_ether.h>
#include <linux/slab.h>
#include <net/dsa.h>
#include <net/netdev_lock.h>
#include <net/sock.h>
#include <linux/if_vlan.h>
#include <net/switchdev.h>
@ -30,13 +31,13 @@
* Determine initial path cost based on speed.
* using recommendations from 802.1d standard
*
* Since driver might sleep need to not be holding any locks.
* Since driver might sleep, we need to not be holding any bridge spinlocks.
*/
static int port_cost(struct net_device *dev)
{
struct ethtool_link_ksettings ecmd;
if (!__ethtool_get_link_ksettings(dev, &ecmd)) {
if (!netif_get_link_ksettings(dev, &ecmd)) {
switch (ecmd.base.speed) {
case SPEED_10000:
return 2;
@ -436,7 +437,9 @@ static struct net_bridge_port *new_nbp(struct net_bridge *br,
p->br = br;
netdev_hold(dev, &p->dev_tracker, GFP_KERNEL);
p->dev = dev;
netdev_lock_ops(dev);
p->path_cost = port_cost(dev);
netdev_unlock_ops(dev);
p->priority = 0x8000 >> BR_PORT_BITS;
p->port_no = index;
p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;