Rolf Neugebauer reported very long delays at netns dismantle.
Eric W. Biederman was kind enough to look at this problem
and noticed synchronize_net() occurring from netif_napi_del() that was
added in linux-4.5
Busy polling makes no sense for tunnels NAPI.
If busy poll is used for sessions over tunnels, the poller will need to
poll the physical device queue anyway.
netif_tx_napi_add() could be used here, but function name is misleading,
and renaming it is not stable material, so set NAPI_STATE_NO_BUSY_POLL
bit directly.
This will avoid inserting gro_cells napi structures in napi_hash[]
and avoid the problematic synchronize_net() (per possible cpu) that
Rolf reported.
Fixes: 93d05d4a32 ("net: provide generic busy polling to all NAPI drivers")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Tested-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
so that the caller can update stats accordingly, if needed
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
As David pointed out, spinlock are no longer needed
to protect the per cpu queues used in gro cells infrastructure.
Also use new napi_complete_done() API so that gro_flush_timeout
tweaks have an effect.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the ipip tunnel, the skb->queue_mapping is lost in ipip_rcv().
All skb will be queued to the same cell->napi_skbs. The
gro_cell_poll is pinned to one core under load. In production traffic,
we also see severe rx_dropped in the tunl iface and it is probably due to
this limit: skb_queue_len(&cell->napi_skbs) > netdev_max_backlog.
This patch is trying to alloc_percpu(struct gro_cell) and schedule
gro_cell_poll to process the skb in the same core.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Dmitry Kravkov reported packet drops for GRE packets since GRO support
was added.
There is a race in gro_cell_poll() because we call napi_complete()
without any synchronization with a concurrent gro_cells_receive()
Once bug was triggered, we queued packets but did not schedule NAPI
poll.
We can fix this issue using the spinlock protected the napi_skbs queue,
as we have to hold it to perform skb dequeue anyway.
As we open-code skb_dequeue(), we no longer need to mask IRQS, as both
producer and consumer run under BH context.
Bug added in commit c9e6bc644e (net: add gro_cells infrastructure)
Reported-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds a new include file (include/net/gro_cells.h), to bring GRO
(Generic Receive Offload) capability to tunnels, in a modular way.
Because tunnels receive path is lockless, and GRO adds a serialization
using a napi_struct, I chose to add an array of up to
DEFAULT_MAX_NUM_RSS_QUEUES cells, so that multi queue devices wont be
slowed down because of GRO layer.
skb_get_rx_queue() is used as selector.
In the future, we might add optional fanout capabilities, using rxhash
for example.
With help from Ben Hutchings who reminded me
netif_get_num_default_rss_queues() function.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
