From: Eric Dumazet Date: Tue, 15 Nov 2016 00:28:42 +0000 (-0800) Subject: gro_cells: mark napi struct as not busy poll candidates X-Git-Tag: v4.8.14~45 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8070f33be6c4f7a947db40658a116ef135b54e74;p=thirdparty%2Fkernel%2Fstable.git gro_cells: mark napi struct as not busy poll candidates [ 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 Reported-by: Rolf Neugebauer Reported-by: Eric W. Biederman Acked-by: Cong Wang Tested-by: Rolf Neugebauer Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/include/net/gro_cells.h b/include/net/gro_cells.h index d15214d673b2e..2a1abbf8da743 100644 --- a/include/net/gro_cells.h +++ b/include/net/gro_cells.h @@ -68,6 +68,9 @@ static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *de 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); }