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authorEric Dumazet <edumazet@google.com>2024-04-15 23:07:28 +0200
committerJakub Kicinski <kuba@kernel.org>2024-04-18 03:22:52 +0200
commit0f022d32c3eca477fbf79a205243a6123ed0fe11 (patch)
treefe0a49f92c3127dae86f34b3328733447c3fca9b /net/sched/sch_generic.c
parents390/ism: Properly fix receive message buffer allocation (diff)
downloadlinux-0f022d32c3eca477fbf79a205243a6123ed0fe11.tar.xz
linux-0f022d32c3eca477fbf79a205243a6123ed0fe11.zip
net/sched: Fix mirred deadlock on device recursion
When the mirred action is used on a classful egress qdisc and a packet is mirrored or redirected to self we hit a qdisc lock deadlock. See trace below. [..... other info removed for brevity....] [ 82.890906] [ 82.890906] ============================================ [ 82.890906] WARNING: possible recursive locking detected [ 82.890906] 6.8.0-05205-g77fadd89fe2d-dirty #213 Tainted: G W [ 82.890906] -------------------------------------------- [ 82.890906] ping/418 is trying to acquire lock: [ 82.890906] ffff888006994110 (&sch->q.lock){+.-.}-{3:3}, at: __dev_queue_xmit+0x1778/0x3550 [ 82.890906] [ 82.890906] but task is already holding lock: [ 82.890906] ffff888006994110 (&sch->q.lock){+.-.}-{3:3}, at: __dev_queue_xmit+0x1778/0x3550 [ 82.890906] [ 82.890906] other info that might help us debug this: [ 82.890906] Possible unsafe locking scenario: [ 82.890906] [ 82.890906] CPU0 [ 82.890906] ---- [ 82.890906] lock(&sch->q.lock); [ 82.890906] lock(&sch->q.lock); [ 82.890906] [ 82.890906] *** DEADLOCK *** [ 82.890906] [..... other info removed for brevity....] Example setup (eth0->eth0) to recreate tc qdisc add dev eth0 root handle 1: htb default 30 tc filter add dev eth0 handle 1: protocol ip prio 2 matchall \ action mirred egress redirect dev eth0 Another example(eth0->eth1->eth0) to recreate tc qdisc add dev eth0 root handle 1: htb default 30 tc filter add dev eth0 handle 1: protocol ip prio 2 matchall \ action mirred egress redirect dev eth1 tc qdisc add dev eth1 root handle 1: htb default 30 tc filter add dev eth1 handle 1: protocol ip prio 2 matchall \ action mirred egress redirect dev eth0 We fix this by adding an owner field (CPU id) to struct Qdisc set after root qdisc is entered. When the softirq enters it a second time, if the qdisc owner is the same CPU, the packet is dropped to break the loop. Reported-by: Mingshuai Ren <renmingshuai@huawei.com> Closes: https://lore.kernel.org/netdev/20240314111713.5979-1-renmingshuai@huawei.com/ Fixes: 3bcb846ca4cf ("net: get rid of spin_trylock() in net_tx_action()") Fixes: e578d9c02587 ("net: sched: use counter to break reclassify loops") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Victor Nogueira <victor@mojatatu.com> Reviewed-by: Pedro Tammela <pctammela@mojatatu.com> Tested-by: Jamal Hadi Salim <jhs@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20240415210728.36949-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/sched/sch_generic.c')
-rw-r--r--net/sched/sch_generic.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index ff5336493777..4a2c763e2d11 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -974,6 +974,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
sch->enqueue = ops->enqueue;
sch->dequeue = ops->dequeue;
sch->dev_queue = dev_queue;
+ sch->owner = -1;
netdev_hold(dev, &sch->dev_tracker, GFP_KERNEL);
refcount_set(&sch->refcnt, 1);