Re: [PATCH v4 0/2] bpf, sockmap: handle spurious tcp_msg_wait_data() wakeup

[Jiayuan Chen <jiayuan.chen@linux.dev>]

On 7/16/26 5:35 AM, Nnamdi Onyeyiri wrote:
> Spurious wakeups in tcp_msg_wait_data() isn't being handled by
> tcp_bpf_recvmsg() and tcp_bpf_recvmsg_parser(), leading to unexpected
> EAGAIN errors returned by recvfrom()/recv().  Adding handling for the
> wakeup and a selftest.
>
> This issue was first discovered in an application that adds sockets to
> a sockmap as a way to view the received data.  No redirects or any
> other operations are performed.
>
> Sashiko has noted a few other pre-existing issues in the same area
> (https://patch.msgid.link/20260714205118.17DB11F000E9@smtp.kernel.org)
> that can lead to EAGAIN in tcp_bpf_recvmsg() and
> tcp_bpf_recvmsg_parser().  A local run of Sashiko also identified a
> potential issue in tcp_bpf_recvmsg() handling zero-data FIN packets when
> the MSG_PEEK flag is set.  To prevent this patchset from growing too
> large, I intend to submit follow up patches to address these once this
> one has been accepted.
>
> Changes in v2:
> - In tcp_bpf_recvmsg, handle signals and the socket closing in the loop.
> - Fix spurious wakeups when SO_RCVTIMEO has been set on the socket.
> - Link to v1: https://patch.msgid.link/ak_rR-Skd8Mvn4mH@localhost.localdomain
>
> Changes in v3:
> - Added the sockmap_recvfrom selftest.
> - Link to v2: https://patch.msgid.link/alFRK66z45eDNZA7@localhost.localdomain
>
> Changes in v4:
> - Fix potential data loss in tcp_bpf_recvmsg() when a FIN or RST has
>    been received.
> - Check the return code of pthread_create() in the selftest.
> - Fix race caused by using EXPECT macros in a thread in selftest.
> - Link to v3: https://patch.msgid.link/20260714203927.32289-1-nnamdio@gmail.com

Please do not send a patch by replying to an old thread.


> Signed-off-by: Nnamdi Onyeyiri <nnamdio@gmail.com>
> ---
> Nnamdi Onyeyiri (2):
>    bpf, sockmap: handle spurious tcp_msg_wait_data() wakeup
>    bpf, sockmap: handle spurious tcp_msg_wait_data() wakeup


Please use a commit subject like "selftests/bpf: add selftest xxx" for 
the selftest patch.



>
>   net/ipv4/tcp_bpf.c                            |  69 +++-
>   tools/testing/selftests/net/.gitignore        |   2 +
>   tools/testing/selftests/net/Makefile          |   5 +
>   .../selftests/net/sockmap_recvfrom.bpf.c      |  31 ++
>   .../testing/selftests/net/sockmap_recvfrom.c  | 299 ++++++++++++++++++


Please use existing test frameworks such as sockmap_basic.c or 
sockmap_strp.c.