From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (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 4F79E3438BA for ; Tue, 2 Jun 2026 17:42:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780422124; cv=none; b=hzI3zLjAQyw9YLbqQPzydMnhJ8JTNSoMIfJzOo3WQBX15OSPpBdDINOtLb9tHJbiYiVupj1n1Z9OEBCb3b+uVYuD6dXpLsyLgXqS2IIJEPsPmmCycmTAVZFpPg0C9bfpxjctzrJFqdgvIP2lfItnclOI35bwA8pmlPGqI+Y3yM0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780422124; c=relaxed/simple; bh=RlTs4+CvmQBcuzjPaawGE+Su+7rLHOBZtuvgu4cIVl4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=cHSp5duapjguy/e0YpqhQMntRhV6oHHKV+SjoFndv+97B6pWOoBnOY6H1VuTklwWFI1FHKCNoD+GacyqnqML6JtkA/kPZ0dRyHMdV3QoULQUjv8628/3WdwSBqlNSuwmfk0UD1eyNZZA6f4J5ZHHDVPQgCNrh/QFtfTIPUhsMGU= 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=KufFmmHx; arc=none smtp.client-ip=209.85.210.201 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="KufFmmHx" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-8422b544a4bso2179214b3a.3 for ; Tue, 02 Jun 2026 10:42:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780422122; x=1781026922; 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=iotGOx3jMR4tDVWp1JTzlSSm5z5uHBCJINbc/HPb57Q=; b=KufFmmHx9vvp8BQGBwqg7SApea5i36sUXQxWVbsyxl9WDnCTQmLZddznAfk03+n7a7 GvZf48sbW59jy4HwRVhlGKPjjWip3MBIfIiJ6JvOD6OxpJX/OqdZUyu8kJiEtQunloYs 1JF3YTPRDNnp+vN1/rJob5H6ttyznk17ir0NDduZTLasf47NXesJyBsYaKV2sE3CwjJc bSzEHZw87969dCrh7AWdc1b+AToaP9hynxLz5ZCKvcB3WXGckTDldYgCSrXBibMkhFXi 016/JmOjmYgZjr3FJ6Srl3Dgdy6W0i+9T5L44RwBY4yW6XKfj8q2uAhJC6Kbw7FwNugA kDaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780422122; x=1781026922; 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=iotGOx3jMR4tDVWp1JTzlSSm5z5uHBCJINbc/HPb57Q=; b=SAOcVlnbmYdH0bVKBZgWvB8hUQMW8Spr20PeQDtH/U1e2407KWqVz5UnTkfDf7Z7uS RoTFyh8qQITl5S89dHJTwhymN6DpaTBnsdnsZkkV0KhcMP6ZwYqGlPylIZNw4Yl5jfAI UjanAE/u0gZqymUWzXhwMitCxvxl3iAjnXYzAySXSuCbhQdMxh1+l1G6+qmKfOMAGy9v hphJm3M8uuZLjskci1F50YEKYIW8TJGEMmu2RwMGP9lifUKLgbFZs4LvTqmwxTVYtNha PpOOEqtiWRXTzE7dnJMWts9qLn+SHcTFSxglkgapJ6FKBoLELHUVz1d8e6sHVipG1D3/ i1dA== X-Forwarded-Encrypted: i=1; AFNElJ8uPIRvc7fPavcqbXpq7s7pKZGGEmdNBPmxC7JPnREeqoV/rZ/rtDWIRXuy1SjjNrdxN8RR7JluclQ/eARvDezj@vger.kernel.org X-Gm-Message-State: AOJu0YzKNhrEZk1W9wJ5NcBD+l0crCMc2alFKkZ6QT3+KTt/s0F4+VQu bndqgsJEytD741UoAJuydzK7x8kLBixDA1H5Wy1CUlPXtyxTvzNivhD0d6jS81ZTZt5T+x5q/9t h3BGMAXP1Gg== X-Received: from pfes4.prod.google.com ([2002:aa7:8d44:0:b0:82f:6a26:5f78]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2d01:b0:842:6e1f:c8fc with SMTP id d2e1a72fcca58-8428310ebf1mr459416b3a.32.1780422122197; Tue, 02 Jun 2026 10:42:02 -0700 (PDT) Date: Tue, 2 Jun 2026 10:41:18 -0700 In-Reply-To: <20260602174129.3192312-1-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: <20260602073132.2653307-1-irogers@google.com> <20260602174129.3192312-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.1013.g208068f2d8-goog Message-ID: <20260602174129.3192312-8-irogers@google.com> Subject: [PATCH v8 07/18] 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-Type: text/plain; charset="UTF-8" Update check_if_command_finished() and wait_or_whine() to handle invalid PIDs gracefully (<= 0) by setting cmd->finished = 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. Assisted-by: Gemini-CLI:Google Gemini 3 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) static int wait_or_whine(struct child_process *cmd, bool block) { - bool finished = cmd->finished; - int result = cmd->finish_result; + bool finished; + int result; + + if (cmd->pid <= 0) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -ERR_RUN_COMMAND_FORK; + return cmd->finish_result; + } + + finished = cmd->finished; + result = cmd->finish_result; while (!finished) { int status, code; @@ -233,7 +243,18 @@ 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) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -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 *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; -- 2.54.0.1013.g208068f2d8-goog