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 DAD801D6195 for ; Wed, 28 May 2025 18:41:11 +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=1748457671; cv=none; b=d8yHj+99PhyLqcrUlbQRQM8m7L6gxNpvYtInIbM/dvQJCI7GwV87M9OFBRXGN669rBLWDqPC2buCoBNZDEkXqXEssgiozHPtOtTsMDEY/2FTX2CtjIWbX0b8X1v9T/HwOc+uSrkX8LWIq4dbZRZKV/B8LapfgE/DfG9ZMGz1UFk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748457671; c=relaxed/simple; bh=anInPSvL/83FHSBSN+bKogNvYIU2+g5qwkPfCRkKlrQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Immh5jE1DCk8tqo3NSS7sOWt7OveTkXTmSJuOGlJIEjDC0nu0ss/HGfDQg7rSVLnfWnVrRGXdPXF+B0HqgQd0XhhQo5I70BXC58MyQbxDw5/46hcSGETKZoTImKcAOAhlXgn/aBXPB0CMV+gDOAZYF+jwTdDls4sPmE+dWYHKjA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=heE0mFq0; 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="heE0mFq0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B78FC4CEE3; Wed, 28 May 2025 18:41:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748457671; bh=anInPSvL/83FHSBSN+bKogNvYIU2+g5qwkPfCRkKlrQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=heE0mFq015GgFv7vFUJYPY4VrZ1v1CXcUmYPkadP2vVNN1sQqZRD2UHyLkpEXbt6U jK6+jqKie8+90EsWCmnZpplR/4jLYXHPW/sQk+SneMUo/qgZRBdrm93ve5WiZwUpTc omfti4V3dTbfq72HILqH69mLT3tX6Qk0k5nofv08SWtNL60br64h3HF1i3YP2VYcBX i0xYOasT0Tk5MFKF4vSOYXOt4x7RJ/BSfrYQ3JJD/rHSBkrsqzo0uZ/fcoUbQd9eDI QodwbMVbblOEOClpeediQ5fCyKJkWw/OzzvlCaEPCi/K4ALePAjQYbcPa0HPGyPzxf p5k5bn+6z8VpA== Date: Wed, 28 May 2025 15:41:08 -0300 From: Arnaldo Carvalho de Melo To: Howard Chu Cc: Anubhav Shelat , mpetlan@redhat.com, namhyung@kernel.org, irogers@google.com, linux-perf-users@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, adrian.hunter@intel.com, kan.liang@linux.intel.com, dapeng1.mi@linux.intel.com, james.clark@linaro.org Subject: Re: [PATCH] perf trace: always print return value for syscalls with set errpid Message-ID: References: <20250403160411.159238-2-ashelat@redhat.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: On Thu, Apr 03, 2025 at 08:26:52PM -0700, Howard Chu wrote: > [Resend due to rejection by mailing list] > > Hello Anubhav, > > Thanks for doing this :) > > On Thu, Apr 3, 2025 at 9:06 AM Anubhav Shelat wrote: > > > > Currently some syscalls that have errpid set to true do not print a > > return value in perf trace. 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 > > > > Signed-off-by: Anubhav Shelat > > Reviewed-by: Howard Chu Thanks, applied after rewording it a bit to mention that this not related to rseq/set_robust_list as those shouldn't be using errpid, but that the problem predates that and added this, where the problem started: Fixes: 11c8e39f5133aed9 ("perf trace: Infrastructure to show COMM strings for syscalls returning PIDs") - Arnaldo