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[86.153.201.25]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47febfe5d7csm7233885f8f.15.2026.08.05.01.22.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Aug 2026 01:22:22 -0700 (PDT) Date: Wed, 5 Aug 2026 09:22:20 +0100 From: Nnamdi Onyeyiri To: bpf@vger.kernel.org, davem@davemloft.net, edumazet@google.com, horms@kernel.org, jakub@cloudflare.com, jiayuan.chen@linux.dev, john.fastabend@gmail.com, kuba@kernel.org, kuniyu@google.com, ncardwell@google.com, netdev@vger.kernel.org, pabeni@redhat.com, sashiko-reviews@lists.linux.dev, linux-kernel@vger.kernel.org, emil@etsalapatis.com Subject: Re: [PATCH v7 0/2] bpf, sockmap: handle spurious tcp_msg_wait_data() wakeup Message-ID: References: <20260721223807.75101-1-nnamdio@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260721223807.75101-1-nnamdio@gmail.com> On Tue, Jul 21, 2026 at 11:38:05PM +0100, Nnamdi Onyeyiri wrote: > Spurious wakeups in tcp_msg_wait_data() aren'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 v7: > - In tcp_bpf_recvmsg check for data in the TCP_CLOSE, !timeo and > signal_pending branches. > - Refactored changes to tcp_bpf_recvmsg to reduce duplication. > - Increase the number of iterations in the selftests. > - Documented selftests numeric constants. > - Link to v6: https://patch.msgid.link/20260720171535.67867-1-nnamdio@gmail.com > > Changes in v6: > - Closing the file descriptor in the selftest worker thread. > - Ensuring the selftest loop breaks early for an error in the worker > thread. > - Added comments to selftest regarding focus on EAGAIN error. > - Updated selftest commit message to imperative mood. > - Link to v5: https://patch.msgid.link/20260717155348.54975-1-nnamdio@gmail.com > > Changes in v5: > - Move selftest from net into bpf/prog_tests/sockmap_basic.c > - Link to v4: https://patch.msgid.link/20260715213538.37229-1-nnamdio@gmail.com > > 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 > > Changes in v3: > - Added the sockmap_recvfrom selftest. > - Link to v2: https://patch.msgid.link/alFRK66z45eDNZA7@localhost.localdomain > > 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 > > Signed-off-by: Nnamdi Onyeyiri > --- > Nnamdi Onyeyiri (2): > bpf, sockmap: handle spurious tcp_msg_wait_data() wakeup > selftests/bpf: add sockmap recvfrom EAGAIN selftest > > net/ipv4/tcp_bpf.c | 72 ++++++++-- > .../selftests/bpf/prog_tests/sockmap_basic.c | 136 ++++++++++++++++++ > 2 files changed, 199 insertions(+), 9 deletions(-) > > -- > 2.52.0 > Hi all, just wondering if you need anything more from me on this?