From: Alexander Lobakin <alobakin@dlink.ru>
To: "David S. Miller" <davem@davemloft.net>
Cc: Edward Cree <ecree@solarflare.com>,
Jiri Pirko <jiri@mellanox.com>,
Eric Dumazet <edumazet@google.com>,
Ido Schimmel <idosch@mellanox.com>,
Paolo Abeni <pabeni@redhat.com>,
Petr Machata <petrm@mellanox.com>,
Sabrina Dubroca <sd@queasysnail.net>,
Florian Fainelli <f.fainelli@gmail.com>,
Jassi Brar <jaswinder.singh@linaro.org>,
Manish Chopra <manishc@marvell.com>,
GR-Linux-NIC-Dev@marvell.com,
Johannes Berg <johannes.berg@intel.com>,
Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
Luca Coelho <luciano.coelho@intel.com>,
Intel Linux Wireless <linuxwifi@intel.com>,
Kalle Valo <kvalo@codeaurora.org>,
Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>,
"Kenneth R. Crudup" <kenny@panix.com>,
Alexander Lobakin <alobakin@dlink.ru>,
netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH net] net: wireless: intel: iwlwifi: fix GRO_NORMAL packet stalling
Date: Wed, 27 Nov 2019 12:41:23 +0300 [thread overview]
Message-ID: <20191127094123.18161-1-alobakin@dlink.ru> (raw)
Commit 6570bc79c0df ("net: core: use listified Rx for GRO_NORMAL in
napi_gro_receive()") has applied batched GRO_NORMAL packets processing
to all napi_gro_receive() users, including mac80211-based drivers.
However, this change has led to a regression in iwlwifi driver [1][2] as
it is required for NAPI users to call napi_complete_done() or
napi_complete() and the end of every polling iteration, whilst iwlwifi
doesn't use NAPI scheduling at all and just calls napi_gro_flush().
In that particular case, packets which have not been already flushed
from napi->rx_list stall in it until at least next Rx cycle.
Fix this by adding a manual flushing of the list to iwlwifi driver right
before napi_gro_flush() call to mimic napi_complete() logics.
I prefer to open-code gro_normal_list() rather than exporting it for 2
reasons:
* to prevent from using it and napi_gro_flush() in any new drivers,
as it is the *really* bad way to use NAPI that should be avoided;
* to keep gro_normal_list() static and don't lose any CC optimizations.
I also don't add the "Fixes:" tag as the mentioned commit was only a
trigger that only exposed an improper usage of NAPI in this particular
driver.
[1] https://lore.kernel.org/netdev/PSXP216MB04388962C411CD0B17A86F47804A0@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM
[2] https://bugzilla.kernel.org/show_bug.cgi?id=205647
Signed-off-by: Alexander Lobakin <alobakin@dlink.ru>
---
drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
index a4d325fcf94a..452da44a21e0 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
@@ -1421,6 +1421,7 @@ static struct iwl_rx_mem_buffer *iwl_pcie_get_rxb(struct iwl_trans *trans,
static void iwl_pcie_rx_handle(struct iwl_trans *trans, int queue)
{
struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
+ struct napi_struct *napi;
struct iwl_rxq *rxq;
u32 r, i, count = 0;
bool emergency = false;
@@ -1526,8 +1527,16 @@ static void iwl_pcie_rx_handle(struct iwl_trans *trans, int queue)
if (unlikely(emergency && count))
iwl_pcie_rxq_alloc_rbs(trans, GFP_ATOMIC, rxq);
- if (rxq->napi.poll)
- napi_gro_flush(&rxq->napi, false);
+ napi = &rxq->napi;
+ if (napi->poll) {
+ if (napi->rx_count) {
+ netif_receive_skb_list(&napi->rx_list);
+ INIT_LIST_HEAD(&napi->rx_list);
+ napi->rx_count = 0;
+ }
+
+ napi_gro_flush(napi, false);
+ }
iwl_pcie_rxq_restock(trans, rxq);
}
--
2.24.0
next reply other threads:[~2019-11-27 9:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 9:41 Alexander Lobakin [this message]
2019-11-27 9:58 ` [PATCH net] net: wireless: intel: iwlwifi: fix GRO_NORMAL packet stalling Luciano Coelho
2019-11-27 10:12 ` Alexander Lobakin
[not found] ` <PSXP216MB0438B2F163C635F8B8B4AD8AA4440@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM>
2019-11-27 10:29 ` Alexander Lobakin
2019-11-27 11:16 ` Nicholas Johnson
2019-11-27 11:44 ` Alexander Lobakin
2019-11-27 13:38 ` Kalle Valo
2019-11-27 16:05 ` Edward Cree
2019-11-27 16:31 ` Alexander Lobakin
2019-11-27 19:23 ` David Miller
2019-11-27 19:28 ` Alexander Lobakin
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