From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f202.google.com (mail-dy1-f202.google.com [74.125.82.202]) (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 3D53DB640 for ; Mon, 1 Jun 2026 00:06:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780272372; cv=none; b=gEbjrj3gYWLEuZ6X88pKRq5MKycrNw+DF69JZ2+Ck+1FveJGtjNMo0yxwcN+IRdYUvpVmA3rqog3BF6bEyB1Z7cqtYqBTH54yVLyGh/cfaPXZ14Jsk7wyupJAG0J4WkW6YZayz2aezp3VJlmm/v3QUHDtE7gt8guygvQxabRRBo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780272372; c=relaxed/simple; bh=dvReU4g/NxS8DLIsJ2sbcFS0Fd6nVsGlSNQltEjnBZw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=lvYF2sVRxsKV4A5GM3GVfXXBEN2SuY+sNcukKvaNE72XXT6hbeoN9NOI/QmRGT6GXlvAJkgbObnwkkUY2K33Fo9nbI5tPPZdUegc5JJ6+11xaicHj3NKXVV2fpVeTWrj/EDA0avXVivyoOQxnNVR+QSxHKFCUnG4fZRJQ0A71fg= 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=lEGDea2q; arc=none smtp.client-ip=74.125.82.202 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="lEGDea2q" Received: by mail-dy1-f202.google.com with SMTP id 5a478bee46e88-304df51ff3eso3529460eec.0 for ; Sun, 31 May 2026 17:06:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780272368; x=1780877168; 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=h9fLZuj/ySLLFaADzST448l4SO7NZ4u7R/46YrlFeHI=; b=lEGDea2qCXS/4ccWDepxg89egqbgPhYaNU4JVMVUVxJvF/IfvJlVs9Djy0Pvw8Ck41 LBDTxJbN4UwkSUW2NFz3n5p+R+5IOJWgxBfBXouy8iv6g4tud+wwV08g7vT3+AmIl62w v7Qz86s2ItWmZbZ3LC3a5X+0RbTlHDQNFPKT/oLeXM/S6IktHzjZMVTRCUsGIsvBbKv3 JhZaeE1TQRGk7t0EnPc6XM/lXNTG0SoKYfnCDDxqxo1fJSDC2onQLz+HOUKfBmSyoOgC abpZdbbiML8NUeIY8/OB3nSYm5nLULgSLoU222jGp1hWpO1c7ufPZapndquBRJG9oWxw TIOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780272368; x=1780877168; 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=h9fLZuj/ySLLFaADzST448l4SO7NZ4u7R/46YrlFeHI=; b=pXRydM31fEDH0iJKAKBbdrP1AvwmKe7mDAflO5o3+zjsYSUi5ycvUFlIxGzJyZ1JUs e9hEleMdZpqi+NyBAedC8+/cFO0iAXZo495BqQINi0AnILj/pKeNpDSdf5Ieh5/pSbli wcr+M38UbWk/ciszbA+Dv8+WDQyH07Ut8sCWwqq0Rb3wJlm6wJPFhC4nMIzMtu/6mC1w Pt+Irv/PwvSedaczF28KK2J+pUlSCiPcGE2AjoI3KzwC6phMeBJ1FA/N6JdYlAWqkaV/ m+svJ6ON7kFdbV9k56HBzR++b7uUAcm0nMOO/cyLDOhLQx4G43716wj3rlBOUZ3nP/Wi nLvw== X-Forwarded-Encrypted: i=1; AFNElJ8vjPh3LMb3G4vFOLpDqgi91PRSn/1+rDTjs4KzULGSKGTqo19OtP7d1ruyDm5LXKajJiKSs0kAy79+W46m7cK7@vger.kernel.org X-Gm-Message-State: AOJu0Yxf205jFKs6C+AmIi4bxjcHUsX+OhuuRx8d/z4wcV6RD1/HPjgj gIuubBS9amuc2IOMqDUYYFik13xy6QvEtioay4nRUu8zG4Qd5ulKH89V+lfS9ITNco2XRqolqw2 d1/HpCFaKow== X-Received: from dleb1-n1.prod.google.com ([2002:a05:701b:4241:10b0:136:8134:c2ed]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:6085:b0:130:73ed:208 with SMTP id a92af1059eb24-137d3bf3fbdmr3244860c88.9.1780272368172; Sun, 31 May 2026 17:06:08 -0700 (PDT) Date: Sun, 31 May 2026 17:05:39 -0700 In-Reply-To: <20260601000548.1195604-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260531082235.940833-1-irogers@google.com> <20260601000548.1195604-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260601000548.1195604-7-irogers@google.com> Subject: [PATCH 06/15] tools subcmd: Robust fallback and existence checks for process reaping From: Ian Rogers To: irogers@google.com, acme@kernel.org, adrian.hunter@intel.com, namhyung@kernel.org Cc: 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-Type: text/plain; charset="UTF-8" Update check_if_command_finished() to check if cmd->pid <= 0 to avoid reaping process hazards when PID has been set to -1 on startup error. Transition the procfs status fopen() fallback to robust waitpid(..., WNOHANG) existence checking upon EMFILE/ENFILE limits. Assisted-by: Gemini-CLI:Google Gemini 3 Signed-off-by: Ian Rogers --- tools/lib/subcmd/run-command.c | 51 ++++++++++++++++++++++++++++++++-- 1 file changed, 49 insertions(+), 2 deletions(-) diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c index b7510f83209a..5ae7b9fa4dab 100644 --- a/tools/lib/subcmd/run-command.c +++ b/tools/lib/subcmd/run-command.c @@ -233,7 +233,14 @@ int check_if_command_finished(struct child_process *cmd) char filename[6 + MAX_STRLEN_TYPE(typeof(cmd->pid)) + 7 + 1]; char status_line[256]; FILE *status_file; +#endif + + if (cmd->finished) + return 1; + if (cmd->pid <= 0) + return 1; +#ifdef __linux__ /* * Check by reading /proc//status as calling waitpid causes * stdout/stderr to be closed and data lost. @@ -241,8 +248,48 @@ int check_if_command_finished(struct child_process *cmd) sprintf(filename, "/proc/%u/status", cmd->pid); status_file = fopen(filename, "r"); if (status_file == 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 == ENOENT) + return 1; + + waiting = waitpid(cmd->pid, &status, WNOHANG); + if (waiting == cmd->pid) { + int result; + int code; + + cmd->finished = 1; + if (WIFSIGNALED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code = WEXITSTATUS(status); + switch (code) { + case 127: + result = -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result = 0; + break; + default: + result = -code; + break; + } + } + cmd->finish_result = result; + return 1; + } + if (waiting < 0 && (errno == ECHILD || errno == ESRCH)) + return 1; + return 0; } while (fgets(status_line, sizeof(status_line), status_file) != NULL) { char *p; -- 2.54.0.823.g6e5bcc1fc9-goog