[PATCH] net: l3mdev: Set OIF flag only when an L3 master exists

[PATCH] net: l3mdev: Set OIF flag only when an L3 master exists

[Haon KIM]

l3mdev_master_ifindex_rcu() may return 0 when the device is not
associated with an L3 master. In that case, l3mdev_update_flow()
currently sets FLOWI_FLAG_L3MDEV_OIF even though flowi_l3mdev
remains 0.

Set FLOWI_FLAG_L3MDEV_OIF only when a non-zero L3 master ifindex
is returned, keeping the flag consistent with flowi_l3mdev.

Signed-off-by: Haon KIM <akrn112@naver.com>
---
 net/l3mdev/l3mdev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
index 5432a5f2dfc8..92b48d6a4301 100644
--- a/net/l3mdev/l3mdev.c
+++ b/net/l3mdev/l3mdev.c
@@ -279,7 +279,8 @@ void l3mdev_update_flow(struct net *net, struct flowi *fl)
 		if (dev) {
 			if (!fl->flowi_l3mdev) {
 				fl->flowi_l3mdev = l3mdev_master_ifindex_rcu(dev);
-				fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF;
+				if (fl->flowi_l3mdev)
+					fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF;
 			}
 
 			/* oif set to L3mdev directs lookup to its table;
-- 
2.37.0

Re: [PATCH] net: l3mdev: Set OIF flag only when an L3 master exists

[Daniel Machon]

Hi Haon,

> l3mdev_master_ifindex_rcu() may return 0 when the device is not
> associated with an L3 master. In that case, l3mdev_update_flow()
> currently sets FLOWI_FLAG_L3MDEV_OIF even though flowi_l3mdev
> remains 0.
> 
> Set FLOWI_FLAG_L3MDEV_OIF only when a non-zero L3 master ifindex
> is returned, keeping the flag consistent with flowi_l3mdev.
> 
> Signed-off-by: Haon KIM <akrn112@naver.com>
> ---
>  net/l3mdev/l3mdev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
> index 5432a5f2dfc8..92b48d6a4301 100644
> --- a/net/l3mdev/l3mdev.c
> +++ b/net/l3mdev/l3mdev.c
> @@ -279,7 +279,8 @@ void l3mdev_update_flow(struct net *net, struct flowi *fl)
>  		if (dev) {
>  			if (!fl->flowi_l3mdev) {
>  				fl->flowi_l3mdev = l3mdev_master_ifindex_rcu(dev);
> -				fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF;
> +				if (fl->flowi_l3mdev)
> +					fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF;

Looking at the readers of this flag, it does not look like this does much, so if
anything this is a no-functional clean-up for net-next, I guess. The commit
description could be more specific about this. Also, the target tree is missing.

>  			}
>  
>  			/* oif set to L3mdev directs lookup to its table;
> -- 
> 2.37.0
> 

/Daniel