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[212.8.243.115]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-473dddcb295sm6521011f8f.35.2026.06.28.23.51.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Jun 2026 23:51:49 -0700 (PDT) Message-ID: <01b025c43dda6efe97646162e61002fdf5fff0e3.camel@redhat.com> Subject: Re: [PATCH v3 04/17] tools/rv: Add selftests From: Gabriele Monaco To: Wen Yang , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Nam Cao , Steven Rostedt , Thomas Weissschuh , Tomas Glozar , John Kacur Date: Mon, 29 Jun 2026 08:51:46 +0200 In-Reply-To: <0c230c01-77c8-4c9e-9f49-ecb9555402cf@linux.dev> References: <20260625121440.116317-1-gmonaco@redhat.com> <20260625121440.116317-5-gmonaco@redhat.com> <0c230c01-77c8-4c9e-9f49-ecb9555402cf@linux.dev> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0BrZXJuZWwub3JnPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmjKX2MCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfIQuAD+JulczTN6l7oJjyroySU55Fbjdvo52xiYYlMjPG7dCTsBAMFI7dSL5zg98I+8 cXY1J7kyNsY6/dcipqBM4RMaxXsOtCRHYWJyaWVsZSBNb25hY28gPGdtb25hY29AcmVkaGF0LmNvb T6InAQTFgoARAIbAwUJBaOagAULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgBYhBMrKEfgLgd0WcK eo9u9KbElYeE3yBQJoymCyAhkBAAoJEO9KbElYeE3yjX4BAJ/ETNnlHn8OjZPT77xGmal9kbT1bC1 7DfrYVISWV2Y1AP9HdAMhWNAvtCtN2S1beYjNybuK6IzWYcFfeOV+OBWRDQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (3.60.1-1.fc44) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Please cut down the context a bit more next time, it makes it much easier to find your review. On Mon, 2026-06-29 at 01:10 +0800, Wen Yang wrote: > On 6/25/26 20:14, Gabriele Monaco wrote: > > + eval "$TIMEOUT" "$command" &> check_output.$$ & > > + bgpid=3D$! > > + pid=3D$(pgrep -f "${command%%[|;&>]*}" | tail -n1) >=20 > The pgrep runs may immediately after the background fork, before the=20 > child process has had time to exec. Yeah I'm aware of this but kind of ignored it for now and never seen it making troubles in practice.. I could add some delay waiting for the task like: while [ -z "$pid" ]; do sleep .5 pid=3D$(pgrep -f "${command%%[|;&>]*}" | tail -n1) done With probably a maximum of some N retrials in case the task never started or we messed up the pattern. That may still race in case the command exits before we pgrep it, but in practice that shouldn't be a problem in our tests. Any better idea? We cannot really rely on the shell's $! because command is using a combination of eval+timer and we'd get the wrong pid. Thanks, Gabriele