From nobody Mon Jun 8 04:16:11 2026 Received: from mail-dl1-f73.google.com (mail-dl1-f73.google.com [74.125.82.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CA63A3815FF for ; Tue, 2 Jun 2026 07:31:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780385518; cv=none; b=A5ZQWJEj+PUpUDUnQsIlE2ubJEB9kavrZyBs8bjPVJhecsLckoQyDH1pkMMO8dxYKhVqSYvI2K9f+1jaRR8QBF3cQ23BSYK/8TmRFyMPh4q0gZ9+Pl3NanBj0wXRjsx4MZWUukjzR9v0sfvKfbt4sD+dzMw5bLsY9beiIuFgxDo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780385518; c=relaxed/simple; bh=NrhJQifWIdjWZpa4T76cPwBhyfTRIBWalPjZpnGarEs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=i8noPX7zC6PgPxFJZH5sKi0VWzhfyl6XUAQYGm0++Rb6MlwLU2zYdUoNsa6v0PeTtNpYfXGDgppyR3P2JmX3r3ScmXTuuEL2VdcJA/JowJplmZ2+H/xRGzlzBDO6d7VtpLqHaUDUIXEJ2GFbvf7hsvwogt62BFiANyVR3QGMrCA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=j09hL2W2; arc=none smtp.client-ip=74.125.82.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="j09hL2W2" Received: by mail-dl1-f73.google.com with SMTP id a92af1059eb24-13537722193so17823585c88.0 for ; Tue, 02 Jun 2026 00:31:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780385514; x=1780990314; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=7sb/QX9TZo/2ucU/CoEjrWNAWFKUT7xSSMp8X290oyk=; b=j09hL2W2q7yGB0wpuk8mBe68oZ3LD+dOKHUsbH8c/vE+mJZuT3YstjoMjDTgHPuGmL 9H/xMr17d01EyJAITR+PDVdHKxIQHnGbbBJvggFRnVVGNAsY/v0///aA2CxpSO1A2PmA Rnl6ZKvVzThqA4Oj+GYe7v9q2/V6bpWzc0tNYHYoM9lpZKda/xPICw/hNweT6S/EXCAc uRxSLcn3sc2yYseRnq/qbAm6hqBBU4PH6Qi4phzEFr01QP67TSGgJMFviS0zZAUfs4Hx ybuemz/hse8T8xjgZDURsCctUKuKZwtAmS4Cqw7ejBM2y++3J/wRk30c6QVfJhu9MSTM nXew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780385514; x=1780990314; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7sb/QX9TZo/2ucU/CoEjrWNAWFKUT7xSSMp8X290oyk=; b=hhoEVeioF+KoUyYQPE9O4l0+7tFqcqUYucDH62eyAIJMmR+6SrW7wuThhEHNVL507o Mgrdl8bb1GYG9TozNRKqkqvFqoPEoWNrQF9mfa6FV2CEm2Jsv1uaBJm6wtQyKUkgN5cS k0igYVHG3GWGNtlDzxLo1sq4b2BRsiWXHBzoqwt5GnneXjaj6+rTvj1jRtWmh7ZWmEhX I2n9Ido9YAVrw0yoV2j3m+pUYPjIhIAEiL4Y4vdGxVHvxso73i7pcHF2iAIO0Dp1jZcb cMz1dIcojbnY55qOaLp+K9NOMoClxUIV3jGNG9+Wiv1yMkKmgGkkCZ03uxv0m2VNKeTk MkMA== X-Forwarded-Encrypted: i=1; AFNElJ854L0/nCGlOWCXb8w9175zqYVbiHdV7nXQxBcP2mtu6VVGc/N4VJErSEvrqgunPTDDjDFWQ2yoMLaUcow=@vger.kernel.org X-Gm-Message-State: AOJu0YwnqV6Ej4IcHZnWdZ8fw6XqObrH3Ugqer/OxXr/q0aurxiZLrcD fr+tkahK3W5pfqakbirGAk8Vpz7X/9xjF/BrOOspOe9NEtj9NJKuXEzEy6txdN1gi50cdEI1p6o whuyniBHI2g== X-Received: from dlc3.prod.google.com ([2002:a05:7022:383:b0:12d:b2ba:b551]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:e23:b0:136:602b:80ac with SMTP id a92af1059eb24-137d413a2eamr6177904c88.27.1780385513482; Tue, 02 Jun 2026 00:31:53 -0700 (PDT) Date: Tue, 2 Jun 2026 00:31:22 -0700 In-Reply-To: <20260602073132.2653307-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260601061401.1541457-1-irogers@google.com> <20260602073132.2653307-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.929.g9b7fa37559-goog Message-ID: <20260602073132.2653307-8-irogers@google.com> Subject: [PATCH v7] tools subcmd: Robust fallback and existence checks for process reaping From: Ian Rogers To: irogers@google.com, acme@kernel.org, namhyung@kernel.org Cc: adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, james.clark@linaro.org, jolsa@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mingo@redhat.com, peterz@infradead.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Update check_if_command_finished() and wait_or_whine() to handle invalid PIDs gracefully (<=3D 0) by setting cmd->finished =3D 1 and returning early. This avoids executing waitpid(-1, ...) or waitpid(0, ...) downstream, which can block or reap parallel tests' exit status causing state corruption. Introduce a fallback mechanism in check_if_command_finished() using waitpid(..., WNOHANG) when /proc//status is inaccessible (e.g. due to EMFILE/ENFILE) to safely check and reap finished children. Signed-off-by: Ian Rogers --- tools/lib/subcmd/run-command.c | 69 ++++++++++++++++++++++++++++++++-- 1 file changed, 65 insertions(+), 4 deletions(-) diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c index b7510f83209a..bd21b8bfd58b 100644 --- a/tools/lib/subcmd/run-command.c +++ b/tools/lib/subcmd/run-command.c @@ -169,8 +169,18 @@ int start_command(struct child_process *cmd) =20 static int wait_or_whine(struct child_process *cmd, bool block) { - bool finished =3D cmd->finished; - int result =3D cmd->finish_result; + bool finished; + int result; + + if (cmd->pid <=3D 0) { + cmd->finished =3D 1; + if (cmd->pid < 0 && cmd->finish_result =3D=3D 0) + cmd->finish_result =3D -ERR_RUN_COMMAND_FORK; + return cmd->finish_result; + } + + finished =3D cmd->finished; + result =3D cmd->finish_result; =20 while (!finished) { int status, code; @@ -233,7 +243,18 @@ int check_if_command_finished(struct child_process *cm= d) char filename[6 + MAX_STRLEN_TYPE(typeof(cmd->pid)) + 7 + 1]; char status_line[256]; FILE *status_file; +#endif =20 + if (cmd->finished) + return 1; + if (cmd->pid <=3D 0) { + cmd->finished =3D 1; + if (cmd->pid < 0 && cmd->finish_result =3D=3D 0) + cmd->finish_result =3D -ERR_RUN_COMMAND_FORK; + return 1; + } + +#ifdef __linux__ /* * Check by reading /proc//status as calling waitpid causes * stdout/stderr to be closed and data lost. @@ -241,8 +262,48 @@ int check_if_command_finished(struct child_process *cm= d) sprintf(filename, "/proc/%u/status", cmd->pid); status_file =3D fopen(filename, "r"); if (status_file =3D=3D NULL) { - /* Open failed assume finish_command was called. */ - return true; + int status; + pid_t waiting; + + /* + * fopen() can fail with ENOENT if the process has been reaped. + * It can also fail with EMFILE/ENFILE if RLIMIT_NOFILE is reached. + * In those cases, use waitpid(..., WNOHANG) to robustly check + * and reap the process if it has exited. + */ + if (errno =3D=3D ENOENT) + return 1; + + waiting =3D waitpid(cmd->pid, &status, WNOHANG); + if (waiting =3D=3D cmd->pid) { + int result; + int code; + + cmd->finished =3D 1; + if (WIFSIGNALED(status)) { + result =3D -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result =3D -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code =3D WEXITSTATUS(status); + switch (code) { + case 127: + result =3D -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result =3D 0; + break; + default: + result =3D -code; + break; + } + } + cmd->finish_result =3D result; + return 1; + } + if (waiting < 0 && (errno =3D=3D ECHILD || errno =3D=3D ESRCH)) + return 1; + return 0; } while (fgets(status_line, sizeof(status_line), status_file) !=3D NULL) { char *p; --=20 2.54.0.929.g9b7fa37559-goog