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Message-ID: <63xflnwiohdfo6m3vnrrxgv2ulplencpwug5qqacugqh7xxpu3@tsczkuqgwurb> Date: Thu, 14 Sep 2023 17:34:18 +0200 From: Stefano Garzarella <sgarzare@...hat.com> To: Arseniy Krasnov <avkrasnov@...utedevices.com> Cc: Stefan Hajnoczi <stefanha@...hat.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, Bobby Eshleman <bobby.eshleman@...edance.com>, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@...rdevices.ru, oxffffaa@...il.com Subject: Re: [PATCH net-next v8 0/4] vsock/virtio/vhost: MSG_ZEROCOPY preparations On Thu, Sep 14, 2023 at 05:05:17PM +0300, Arseniy Krasnov wrote: >Hello Stefano, > >On 14.09.2023 17:07, Stefano Garzarella wrote: >> Hi Arseniy, >> >> On Mon, Sep 11, 2023 at 11:22:30PM +0300, Arseniy Krasnov wrote: >>> Hello, >>> >>> this patchset is first of three parts of another big patchset for >>> MSG_ZEROCOPY flag support: >>> https://lore.kernel.org/netdev/20230701063947.3422088-1-AVKrasnov@sberdevices.ru/ >>> >>> During review of this series, Stefano Garzarella <sgarzare@...hat.com> >>> suggested to split it for three parts to simplify review and merging: >>> >>> 1) virtio and vhost updates (for fragged skbs) <--- this patchset >>> 2) AF_VSOCK updates (allows to enable MSG_ZEROCOPY mode and read >>> tx completions) and update for Documentation/. >>> 3) Updates for tests and utils. >>> >>> This series enables handling of fragged skbs in virtio and vhost parts. >>> Newly logic won't be triggered, because SO_ZEROCOPY options is still >>> impossible to enable at this moment (next bunch of patches from big >>> set above will enable it). >>> >>> I've included changelog to some patches anyway, because there were some >>> comments during review of last big patchset from the link above. >> >> Thanks, I left some comments on patch 4, the others LGTM. >> Sorry to not having spotted them before, but moving >> virtio_transport_alloc_skb() around the file, made the patch a little >> confusing and difficult to review. > >Sure, no problem, I'll fix them! Thanks for review. > >> >> In addition, I started having failures of test 14 (server: host, >> client: guest), so I looked better to see if there was anything wrong, >> but it fails me even without this series applied. >> >> It happens to me intermittently (~30%), does it happen to you? >> Can you take a look at it? > >Yes! sometime ago I also started to get fails of this test, not ~30%, >significantly rare, but it depends on environment I guess, anyway I'm going to >look at this on the next few days Maybe it's just a timing issue in the test, indeed we are expecting 8 bytes but we received only 3 plus the 2 bytes we received before it seems exactly the same bytes we send with the first `send(fd, HELLO_STR, strlen(HELLO_STR), 0);` Since it is a stream socket, it could happen, so we should retry the recv() or just use MSG_WAITALL. Applying the following patch fixed the issue for me (15 mins without errors for now): diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c index 90718c2fd4ea..7b0fed9fc58d 100644 --- a/tools/testing/vsock/vsock_test.c +++ b/tools/testing/vsock/vsock_test.c @@ -1129,7 +1129,7 @@ static void test_stream_virtio_skb_merge_server(const struct test_opts *opts) control_expectln("SEND0"); /* Read skbuff partially. */ - res = recv(fd, buf, 2, 0); + res = recv(fd, buf, 2, MSG_WAITALL); if (res != 2) { fprintf(stderr, "expected recv(2) returns 2 bytes, got %zi\n", res); exit(EXIT_FAILURE); @@ -1138,7 +1138,7 @@ static void test_stream_virtio_skb_merge_server(const struct test_opts *opts) control_writeln("REPLY0"); control_expectln("SEND1"); - res = recv(fd, buf + 2, sizeof(buf) - 2, 0); + res = recv(fd, buf + 2, 8, MSG_WAITALL); if (res != 8) { fprintf(stderr, "expected recv(2) returns 8 bytes, got %zi\n", res); exit(EXIT_FAILURE); I will check better all the cases and send a patch upstream. Anyway it looks just an issue in our test suite :-) Stefano > >Thanks, Arseniy > >> >> host$ ./vsock_test --mode=server --control-port=12345 --peer-cid=4 >> ... >> 14 - SOCK_STREAM virtio skb merge...expected recv(2) returns 8 bytes, got 3 >> >> guest$ ./vsock_test --mode=client --control-host=192.168.133.2 --control-port=12345 --peer-cid=2 >> >> Thanks, >> Stefano >> >
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