Re: [PATCH v2] Revert "vrf: Remove unnecessary RCU-bh critical section"
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2024-09-26 09:03:27
Also in:
stable
greearb@ wrote:
From: Ben Greear <redacted>
This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853.
dev_queue_xmit_nit needs to run with bh locking, otherwise
it conflicts with packets coming in from a nic in softirq
context and packets being transmitted from user context.
================================
WARNING: inconsistent lock state
6.11.0 #1 Tainted: G W
--------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
btserver/134819 [HC0[0]:SC0[0]:HE1:SE1] takes:
ffff8882da30c118 (rlock-AF_PACKET){+.?.}-{2:2}, at: tpacket_rcv+0x863/0x3b30
{IN-SOFTIRQ-W} state was registered at:
lock_acquire+0x19a/0x4f0
_raw_spin_lock+0x27/0x40
packet_rcv+0xa33/0x1320
__netif_receive_skb_core.constprop.0+0xcb0/0x3a90
__netif_receive_skb_list_core+0x2c9/0x890
netif_receive_skb_list_internal+0x610/0xcc0
napi_complete_done+0x1c0/0x7c0
igb_poll+0x1dbb/0x57e0 [igb]
__napi_poll.constprop.0+0x99/0x430
net_rx_action+0x8e7/0xe10
handle_softirqs+0x1b7/0x800
__irq_exit_rcu+0x91/0xc0
irq_exit_rcu+0x5/0x10
[snip]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(rlock-AF_PACKET);
<Interrupt>
lock(rlock-AF_PACKET);
*** DEADLOCK ***
Call Trace:
<TASK>
dump_stack_lvl+0x73/0xa0
mark_lock+0x102e/0x16b0
__lock_acquire+0x9ae/0x6170
lock_acquire+0x19a/0x4f0
_raw_spin_lock+0x27/0x40
tpacket_rcv+0x863/0x3b30
dev_queue_xmit_nit+0x709/0xa40
vrf_finish_direct+0x26e/0x340 [vrf]
vrf_l3_out+0x5f4/0xe80 [vrf]
__ip_local_out+0x51e/0x7a0
[snip]
Fixes: 504fc6f4f7f6 ("vrf: Remove unnecessary RCU-bh critical section")
Link: https://lore.kernel.org/netdev/05765015-f727-2f30-58da-2ad6fa7ea99f@candelatech.com/T/ (local)
Signed-off-by: Ben Greear <redacted>Please Cc: all previous reviewers and folks who participated in the discussion. I entirely missed this. No need to add as Cc tags, just --cc in git send-email will do.
quoted hunk ↗ jump to hunk
--- v2: Edit patch description. drivers/net/vrf.c | 2 ++ net/core/dev.c | 1 + 2 files changed, 3 insertions(+)diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 4d8ccaf9a2b4..4087f72f0d2b 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c@@ -608,7 +608,9 @@ static void vrf_finish_direct(struct sk_buff *skb) eth_zero_addr(eth->h_dest); eth->h_proto = skb->protocol; + rcu_read_lock_bh(); dev_queue_xmit_nit(skb, vrf_dev); + rcu_read_unlock_bh(); skb_pull(skb, ETH_HLEN); }diff --git a/net/core/dev.c b/net/core/dev.c index cd479f5f22f6..566e69a38eed 100644 --- a/net/core/dev.c +++ b/net/core/dev.c@@ -2285,6 +2285,7 @@ EXPORT_SYMBOL_GPL(dev_nit_active); /* * Support routine. Sends outgoing frames to any network * taps currently in use. + * BH must be disabled before calling this.
Unnecessary. Especially patches for stable should be minimal to reduce the chance of conflicts.