Edward Cree wrote 27.11.2019 19:05:
On 27/11/2019 09:41, Alexander Lobakin wrote:
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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[2] https://bugzilla.kernel.org/show_bug.cgi?id=205647
Signed-off-by: Alexander Lobakin <alobakin@xxxxxxxx>
Reviewed-by: Edward Cree <ecree@xxxxxxxxxxxxxx>
Thanks! And you were the first who's found the root of the issue.
Regards,
ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ
