Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.8 01/45] gro_cells: mark napi struct as not busy poll candidates | Date | Fri, 9 Dec 2016 17:20:30 +0100 |
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4.8-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit e88a2766143a27bfe6704b4493b214de4094cf29 ]
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: 93d05d4a320c ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- include/net/gro_cells.h | 3 +++ 1 file changed, 3 insertions(+)
--- a/include/net/gro_cells.h +++ b/include/net/gro_cells.h @@ -68,6 +68,9 @@ static inline int gro_cells_init(struct struct gro_cell *cell = per_cpu_ptr(gcells->cells, i); __skb_queue_head_init(&cell->napi_skbs); + + set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state); + netif_napi_add(dev, &cell->napi, gro_cell_poll, 64); napi_enable(&cell->napi); }
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