[PATCH net] net: ovs: fix ovs_drop_reasons error

[PATCH net] net: ovs: fix ovs_drop_reasons error

[Menglong Dong]

There is something wrong with ovs_drop_reasons. ovs_drop_reasons[0] is
"OVS_DROP_LAST_ACTION", but OVS_DROP_LAST_ACTION == __OVS_DROP_REASON + 1,
which means that ovs_drop_reasons[1] should be "OVS_DROP_LAST_ACTION".

And as Adrian tested, without the patch, adding flow to drop packets
results in:

drop at: do_execute_actions+0x197/0xb20 [openvsw (0xffffffffc0db6f97)
origin: software
input port ifindex: 8
timestamp: Tue Aug 20 10:19:17 2024 859853461 nsec
protocol: 0x800
length: 98
original length: 98
drop reason: OVS_DROP_ACTION_ERROR

With the patch, the same results in:

drop at: do_execute_actions+0x197/0xb20 [openvsw (0xffffffffc0db6f97)
origin: software
input port ifindex: 8
timestamp: Tue Aug 20 10:16:13 2024 475856608 nsec
protocol: 0x800
length: 98
original length: 98
drop reason: OVS_DROP_LAST_ACTION

Fix this by initializing ovs_drop_reasons with index.

Fixes: 9d802da40b7c ("net: openvswitch: add last-action drop reason")
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Tested-by: Adrian Moreno <amorenoz@redhat.com>
Reviewed-by: Adrian Moreno <amorenoz@redhat.com>
---
 net/openvswitch/datapath.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 99d72543abd3..78d9961fcd44 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -2706,7 +2706,7 @@ static struct pernet_operations ovs_net_ops = {
 };
 
 static const char * const ovs_drop_reasons[] = {
-#define S(x)	(#x),
+#define S(x) [(x) & ~SKB_DROP_REASON_SUBSYS_MASK] = (#x),
 	OVS_DROP_REASONS(S)
 #undef S
 };
-- 
2.39.2

Re: [PATCH net] net: ovs: fix ovs_drop_reasons error

[patchwork-bot+netdevbpf]

Hello:

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

On Wed, 21 Aug 2024 20:32:52 +0800 you wrote:
> There is something wrong with ovs_drop_reasons. ovs_drop_reasons[0] is
> "OVS_DROP_LAST_ACTION", but OVS_DROP_LAST_ACTION == __OVS_DROP_REASON + 1,
> which means that ovs_drop_reasons[1] should be "OVS_DROP_LAST_ACTION".
> 
> And as Adrian tested, without the patch, adding flow to drop packets
> results in:
> 
> [...]

Here is the summary with links:
  - [net] net: ovs: fix ovs_drop_reasons error
    https://git.kernel.org/netdev/net/c/57fb67783c40

You are awesome, thank you!
-- 
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