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 D4CE245007; Fri, 12 Jul 2024 20:33:40 +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=1720816420; cv=none; b=o6vFFh9fz2JdYo7kdBkqzRP3bUxFSS7Iqm6U95rNw5b5gDyo8dlIKHcNlfpBUFKTG6MB5tLwxMlb/Rze+bqwAsPcXziGc2T86lkKbQefhX1naaQTOeTJSoQznHWjkHhTak2pdfMHaUkDfwiHdhZKqgX5N2RO3uq9P0iOGBfCn3I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720816420; c=relaxed/simple; bh=IZrFY7jhRqA3akF0qdHbJ7oItv4LQGRvS4/YFZ/3I70=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uVomGZtUCo4q8f+8Bv04KNoSLLNpffkN5y4RnA/FNzA8jwYUvzdaabjU0AaJMCobpqBylJcexn3aTw2YpVfKQ7bJD04sagJY003+sPygGpEuO9rfnOoa9nvnxNL2Fx+XjHoPD4bPtqoBiy8GvpbHj466yrHNe59pWhW8fVjDzbQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=d73hPJsL; 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="d73hPJsL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9019C32782; Fri, 12 Jul 2024 20:33:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720816420; bh=IZrFY7jhRqA3akF0qdHbJ7oItv4LQGRvS4/YFZ/3I70=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=d73hPJsLKNEeECtBzy3M+/XKX2g6xymNy79MJUmnLJ9+C44v0LB48RPy/+/PnRjqn 6u5bU1s0bgJK5lKZ+YzGiO/F4DRMx9qzq0MPaXsP0i1XPGEKJPiFgUAfPTn1AJP6rI xHf+sqOM0vFYM4s3mqEz/L2IoP1QnTMleIcEw7ItzG7ao3UhP2galLiFf29aJ0MmkJ S6MJdLSANvyDcGuSpQV9w+6VX92R6TVfxBHPr+CwgJyH4THXL4Eqdhkefk22pgolfx DIYIOlMaoJ2THXFsovr2bjQ6oDNqxIqTO237W6bXMZ+IOjmX1+MEj0b2fZG0bJmTsc MfFyEA10n51kQ== Date: Fri, 12 Jul 2024 15:33:35 -0500 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 Content-Transfer-Encoding: 8bit In-Reply-To: Hi Ian, On Tue, Jul 02, 2024 at 09:24:50PM -0700, Ian Rogers wrote: > On Tue, Jul 2, 2024 at 8:24 PM Namhyung Kim wrote: > > > > 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.. > > I don't think it'd be unreasonable to say run "perf report" on > Windows, or using wasm inside a web browser. Part of the reason for > doing things this way was to keep the WNOHANG logic although this > change no longer uses it for __linux__. I'm not sure we are ready to run it on other platforms. So I think it's better simply remove it for now. 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 > > >