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net: Avoid overwriting valid skb->napi_id

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This will be useful to allow busy poll for tunneled traffic. In case of
busy poll for sessions over tunnels, the underlying physical device's
queues need to be polled.

Tunnels schedule NAPI either via netif_rx() for backlog queue or
schedule the gro_cell_poll(). netif_rx() propagates the valid skb->napi_id
to the socket. OTOH, gro_cell_poll() stamps the skb->napi_id again by
calling skb_mark_napi_id() with the tunnel NAPI which is not a busy poll
candidate. This was preventing tunneled traffic to use busy poll. A valid
NAPI ID in the skb indicates it was already marked for busy poll by a
NAPI driver and hence needs to be copied into the socket.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Amritha Nambiar 2020-06-18 14:22:15 -07:00 committed by David S. Miller
parent 8eaf8d9940
commit 78e57f152c
1 changed files with 5 additions and 1 deletions
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6
include/net/busy_poll.h
View file

@ -114,7 +114,11 @@ static inline void skb_mark_napi_id(struct sk_buff *skb,
struct napi_struct *napi)
{
#ifdef CONFIG_NET_RX_BUSY_POLL
skb->napi_id = napi->napi_id;
/* If the skb was already marked with a valid NAPI ID, avoid overwriting
* it.
*/
if (skb->napi_id < MIN_NAPI_ID)
skb->napi_id = napi->napi_id;
#endif
}