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AJvYcCXTwW772xY+Jg8pAbfZWDCgrmqlD5tsEY7jothVbgjRbNDn+iBo5xBG1Pv7f/2xKrzLZxg7fl37dBXjLgYPNHf42qTnLRJ7feNR2sQ5RCVqQ8tCJPre7/20zqA0rGtRXgv+tyXlS69FsVep X-Gm-Message-State: AOJu0YyTlLDsdDXkGDkShndnV0cJbiTSntjtZEUvYBMaBPk3XIe9KoOt nfB4xpQo89pVMLF6X9ZR5EWeHEgKQ2AS1Mx3AIzKKNpe+qDQ6K8iBXiXAAkGqAlOIof0yVscO4o czpAcfBesNtpOUpUolxkMYJZHlC0LoU8SPgc= X-Google-Smtp-Source: AGHT+IE9MsTixcTFY2cE03LT8ruG93/33BbQvBX6DoS6IktovOPkcU4CUUgzk0QL0matjkTNT2GCPetnJKf2RQ6TJlU= X-Received: by 2002:a17:907:72c6:b0:a46:13d5:46fe with SMTP id du6-20020a17090772c600b00a4613d546femr1743237ejc.11.1711708890891; Fri, 29 Mar 2024 03:41:30 -0700 (PDT) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240329034243.7929-1-kerneljasonxing@gmail.com> <20240329034243.7929-4-kerneljasonxing@gmail.com> In-Reply-To: From: Jason Xing Date: Fri, 29 Mar 2024 18:40:54 +0800 Message-ID: Subject: Re: [PATCH net-next v3 3/3] tcp: add location into reset trace process To: Eric Dumazet Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, rostedt@goodmis.org, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Jason Xing Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Mar 29, 2024 at 5:13=E2=80=AFPM Eric Dumazet = wrote: > > On Fri, Mar 29, 2024 at 4:43=E2=80=AFAM Jason Xing wrote: > > > > From: Jason Xing > > > > In addition to knowing the 4-tuple of the flow which generates RST, > > the reason why it does so is very important because we have some > > cases where the RST should be sent and have no clue which one > > exactly. > > > > Adding location of reset process can help us more, like what > > trace_kfree_skb does. > > Well, I would prefer a drop_reason here, even if there is no 'dropped' pa= cket. Good idea really. Then we can accurately diagnose which kind of reason exactly causes the RST behavior. I'm not sure if we can reuse the drop_reason here, like adding/using some reasons in enum skb_drop_reason {}? The name is a little bit strange. Oh, I can just print the string of reason directly instead of really using enum skb_drop_reason {}... > > This would be more stable than something based on function names that > could be changed. > > tracepoints do not have to get ugly, we can easily get stack traces if ne= eded. > > perf record -a -g -e tcp:tcp_send_reset ... Ah, yes, I blindly mimic what trace_skb_kfree() and trace_consume_skb() do. Introducing some RST reasons is more reasonable and easier to detect since it's not hard to add four or five reasons only. Thanks, Jason