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 D28922ED161; Tue, 17 Jun 2025 16:18:42 +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=1750177122; cv=none; b=FXgUWSzSBUPVsLwfA6Hqxg3QfSR7Mr0SyyV8mAtqLSrZzD9gQQEC4dS0WG7zx6UD6fl/F/vM6GJ4QqzjWRAnjuNYZSlLKqSBLWKEhsFDc0UgfgJOIAAH6Wf0g2JsBbBqtET8dqkxlBtaqt+OI4lqW56pb8Q7P4Su86BeCNnl0vw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750177122; c=relaxed/simple; bh=Rg5rgER2JLwwrIIL2nN4yG5JEC/ew0XHQEb64zfzDFw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cqVLW2HhdXeSUZsNeAdlhlKOba5fggeHXySFgtKT0ldjB/A8O27x6aBK4CjYoOtepLi7FXNrryl1Xt7+lTliJw9H/AAncKHhslPXNG1uiQ3u2lbWC4mzPYP+vCMNf790Mr2EFZtQVfc+clliEro0DiPaFqsed5Kj5Xg3nCzMGho= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FBH9XTWU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FBH9XTWU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C17BC4CEE3; Tue, 17 Jun 2025 16:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750177122; bh=Rg5rgER2JLwwrIIL2nN4yG5JEC/ew0XHQEb64zfzDFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FBH9XTWUVEGPgdMgNZU2N/IRuV16A4D+kIKcr96Gf/Cj0jcB1pGLmw+P6yHZUTh2I RLG51Sdt+U2RdgYe4B/meFc97RUUMsI32+W5N2ClGjFb8ebopJegovOdj7WnUMJXpP jtu2bmQ8SqCETFXR3s370w9y5n+6aZvkwJ/FaO9M= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Howard Chu , Anubhav Shelat , Namhyung Kim , Adrian Hunter , Alexander Shishkin , Dapeng Mi , Ian Rogers , Ingo Molnar , James Clark , Jiri Olsa , Kan Liang , Mark Rutland , Michael Petlan , Peter Zijlstra , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 6.12 299/512] perf trace: Always print return value for syscalls returning a pid Date: Tue, 17 Jun 2025 17:24:25 +0200 Message-ID: <20250617152431.711885365@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250617152419.512865572@linuxfoundation.org> References: <20250617152419.512865572@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anubhav Shelat [ Upstream commit c7a48ea9b919e2fa0e4a1d9938fdb03e9afe276c ] The syscalls that were consistently observed were set_robust_list and rseq. This is because perf cannot find their child process. This change ensures that the return value is always printed. Before: 0.256 ( 0.001 ms): set_robust_list(head: 0x7f09c77dba20, len: 24) = 0.259 ( 0.001 ms): rseq(rseq: 0x7f09c77dc0e0, rseq_len: 32, sig: 1392848979) = After: 0.270 ( 0.002 ms): set_robust_list(head: 0x7f0bb14a6a20, len: 24) = 0 0.273 ( 0.002 ms): rseq(rseq: 0x7f0bb14a70e0, rseq_len: 32, sig: 1392848979) = 0 Committer notes: As discussed in the thread in the Link: tag below, these two don't return a pid, but for syscalls returning one, we need to print the result and if we manage to find the children in 'perf trace' data structures, then print its name as well. Fixes: 11c8e39f5133aed9 ("perf trace: Infrastructure to show COMM strings for syscalls returning PIDs") Reviewed-by: Howard Chu Signed-off-by: Anubhav Shelat Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Dapeng Mi Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Michael Petlan Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250403160411.159238-2-ashelat@redhat.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/builtin-trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index ee82e858ab200..ebe4fad0d4751 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -2873,8 +2873,8 @@ errno_print: { else if (sc->fmt->errpid) { struct thread *child = machine__find_thread(trace->host, ret, ret); + fprintf(trace->output, "%ld", ret); if (child != NULL) { - fprintf(trace->output, "%ld", ret); if (thread__comm_set(child)) fprintf(trace->output, " (%s)", thread__comm_str(child)); thread__put(child); -- 2.39.5