[PATCH net-next] vrf: Remove unnecessary RCU-bh critical section

[PATCH net-next] vrf: Remove unnecessary RCU-bh critical section

[Ido Schimmel]

dev_queue_xmit_nit() already uses rcu_read_lock() / rcu_read_unlock()
and nothing suggests that softIRQs should be disabled around it.
Therefore, remove the rcu_read_lock_bh() / rcu_read_unlock_bh()
surrounding it.

Tested using [1] with lockdep enabled.

[1]
 #!/bin/bash

 ip link add name vrf1 up type vrf table 100
 ip link add name veth0 type veth peer name veth1
 ip link set dev veth1 master vrf1
 ip link set dev veth0 up
 ip link set dev veth1 up
 ip address add 192.0.2.1/24 dev veth0
 ip address add 192.0.2.2/24 dev veth1
 ip rule add pref 32765 table local
 ip rule del pref 0
 tcpdump -i vrf1 -c 20 -w /dev/null &
 sleep 10
 ping -i 0.1 -c 10 -q 192.0.2.2

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 drivers/net/vrf.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 6043e63b42f9..43f374444684 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -638,9 +638,7 @@ 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);
 	}
-- 
2.40.1

Re: [PATCH net-next] vrf: Remove unnecessary RCU-bh critical section

[Simon Horman]

On Mon, Aug 21, 2023 at 05:23:39PM +0300, Ido Schimmel wrote:
> dev_queue_xmit_nit() already uses rcu_read_lock() / rcu_read_unlock()
> and nothing suggests that softIRQs should be disabled around it.
> Therefore, remove the rcu_read_lock_bh() / rcu_read_unlock_bh()
> surrounding it.
> 
> Tested using [1] with lockdep enabled.
> 
> [1]
>  #!/bin/bash
> 
>  ip link add name vrf1 up type vrf table 100
>  ip link add name veth0 type veth peer name veth1
>  ip link set dev veth1 master vrf1
>  ip link set dev veth0 up
>  ip link set dev veth1 up
>  ip address add 192.0.2.1/24 dev veth0
>  ip address add 192.0.2.2/24 dev veth1
>  ip rule add pref 32765 table local
>  ip rule del pref 0
>  tcpdump -i vrf1 -c 20 -w /dev/null &
>  sleep 10
>  ping -i 0.1 -c 10 -q 192.0.2.2
> 
> Signed-off-by: Ido Schimmel <idosch@nvidia.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next] vrf: Remove unnecessary RCU-bh critical section

[David Ahern]

On 8/21/23 8:23 AM, Ido Schimmel wrote:
> dev_queue_xmit_nit() already uses rcu_read_lock() / rcu_read_unlock()
> and nothing suggests that softIRQs should be disabled around it.
> Therefore, remove the rcu_read_lock_bh() / rcu_read_unlock_bh()
> surrounding it.
> 
> Tested using [1] with lockdep enabled.
> 
> [1]
>  #!/bin/bash
> 
>  ip link add name vrf1 up type vrf table 100
>  ip link add name veth0 type veth peer name veth1
>  ip link set dev veth1 master vrf1
>  ip link set dev veth0 up
>  ip link set dev veth1 up
>  ip address add 192.0.2.1/24 dev veth0
>  ip address add 192.0.2.2/24 dev veth1
>  ip rule add pref 32765 table local
>  ip rule del pref 0
>  tcpdump -i vrf1 -c 20 -w /dev/null &
>  sleep 10
>  ping -i 0.1 -c 10 -q 192.0.2.2
> 
> Signed-off-by: Ido Schimmel <idosch@nvidia.com>
> ---
>  drivers/net/vrf.c | 2 --
>  1 file changed, 2 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net-next] vrf: Remove unnecessary RCU-bh critical section

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 21 Aug 2023 17:23:39 +0300 you wrote:
> dev_queue_xmit_nit() already uses rcu_read_lock() / rcu_read_unlock()
> and nothing suggests that softIRQs should be disabled around it.
> Therefore, remove the rcu_read_lock_bh() / rcu_read_unlock_bh()
> surrounding it.
> 
> Tested using [1] with lockdep enabled.
> 
> [...]

Here is the summary with links:
  - [net-next] vrf: Remove unnecessary RCU-bh critical section
    https://git.kernel.org/netdev/net-next/c/504fc6f4f7f6

You are awesome, thank you!
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