From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD9931799F; Wed, 3 Jul 2024 03:24:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719977041; cv=none; b=JdgVFJzUoq+Z9MRHBMEj94NNDCkiMHwbevo0eL4XFaVcR1om2seaC0VbXRaBJCnFQ1uFH0USEYEHe0lc7RxZcb7YDAjlB2e68wFwWAoK1/eGOPVedk3k4ugEd1X+85oYQXRVz6U6RnBimhTqtNoUWKhEGkfnDR8dZJlaLVquxIc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719977041; c=relaxed/simple; bh=qzEG3oESDXRJMNTCffvSAEMa/1sN/tHpyXP/Rj1Sn+4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z3flJQmVQZBUbKV8i12jvOe/r3XE30NOX6q2sY88ngpTpra+HKRe+Xx3bQ03mdYlplS0bRL1bSi6Z06ntwHK7SBpa3shEbtjpOylqKMsXx6X0QRpFbzjlMXY8n9hnnR/R/tUcyW7eicXHAL3/I2vouoHjkhjG3m4TFe7qBbmz6M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fOr+k0fq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fOr+k0fq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB074C116B1; Wed, 3 Jul 2024 03:24:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719977041; bh=qzEG3oESDXRJMNTCffvSAEMa/1sN/tHpyXP/Rj1Sn+4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fOr+k0fqC1evUmg6/mUVKlLo6zR2tW4KkrPNeoLk/GSHeSOPVEoKjeG261K3q6jUY 4NsIADTauazrNwuRNeEIfuY3KATdXiC3/1rqDVyavOhfYLL2zlPV+AsV5QbypMbE9K 7NTq4pQdUlEAeogk+5qrjIYs0rqumcRMgNp9NpBHF9UwU4dc/4N4oenTQ/RRFjM4l9 /iaTJvhV2SDQMj2wh5yy5gDvqLmaXmkKSOf6kOtV2nZRFpZAAzAuYG67d57Bjn5xVf Tyniog03qtH0xxdV9tC55hFAWHRvW8KRL3w4vWZB7ypYclN7+vZplGZcY7fyOu5FoB FD/ZcLD8PvhpQ== Date: Tue, 2 Jul 2024 20:23:58 -0700 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , James Clark , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v2 1/2] tools subcmd: Add non-waitpid check_if_command_finished() Message-ID: References: <20240701044236.475098-1-irogers@google.com> <20240701044236.475098-2-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240701044236.475098-2-irogers@google.com> Hi Ian, On Sun, Jun 30, 2024 at 09:42:35PM -0700, Ian Rogers wrote: > Using waitpid can cause stdout/stderr of the child process to be > lost. Use Linux's /prod//status file to determine if the process > has reached the zombie state. Use the 'status' file rather than 'stat' > to avoid issues around skipping the process name. > > Signed-off-by: Ian Rogers > --- > tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c > index 4e3a557a2f37..ec06683e77a0 100644 > --- a/tools/lib/subcmd/run-command.c > +++ b/tools/lib/subcmd/run-command.c > @@ -2,6 +2,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block) > > int check_if_command_finished(struct child_process *cmd) > { > +#ifdef __linux__ Is this really necessary? I don't think we plan to support other OS.. Thanks, Namhyung > + char filename[FILENAME_MAX + 12]; > + char status_line[256]; > + FILE *status_file; > + > + /* > + * Check by reading /proc//status as calling waitpid causes > + * stdout/stderr to be closed and data lost. > + */ > + sprintf(filename, "/proc/%d/status", cmd->pid); > + status_file = fopen(filename, "r"); > + if (status_file == NULL) { > + /* Open failed assume finish_command was called. */ > + return true; > + } > + while (fgets(status_line, sizeof(status_line), status_file) != NULL) { > + char *p; > + > + if (strncmp(status_line, "State:", 6)) > + continue; > + > + fclose(status_file); > + p = status_line + 6; > + while (isspace(*p)) > + p++; > + return *p == 'Z'; > + } > + /* Read failed assume finish_command was called. */ > + fclose(status_file); > + return true; > +#else > wait_or_whine(cmd, /*block=*/false); > return cmd->finished; > +#endif > } > > int finish_command(struct child_process *cmd) > -- > 2.45.2.803.g4e1b14247a-goog >