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 83ACA360; Tue, 11 Mar 2025 01:29:32 +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=1741656572; cv=none; b=UoM1xTx9coD5wrtU6peraMb4YNqgDXRywWmONsSTA1A/dfa2FiOkPFOloCyXzRtJbgB5EKLagRCa89+p0k56LFZaeRtlDKdeX+rCRw0NYsBJqYAORPfthifNiFkqtzi66N7peiyFYkMpcq2wMrFGRI2iy9a9e/dTWnTX6mGmBs4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741656572; c=relaxed/simple; bh=TS2WD0LGdmJ3Bg5okMf22/qVCeyY/UfSxXD8aVLF15g=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=uOdTyI1ofdl3k9A3rAMmJfyh0MNiWmJpmkQHmx3a6VdDJUrqukuZXpzb6aW9+7pmNUILHOrOp4WSiHAkldXkWMw0Y8IDV7jBM2i9eXhnYxZzfjM909rj4FcIGIxNk2XrXt/s83HKfNeT8mo77GaFLSE0xcmrJ9FGvnQjM7MRAAQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cg+bgZee; 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="Cg+bgZee" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99764C4CEE5; Tue, 11 Mar 2025 01:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741656572; bh=TS2WD0LGdmJ3Bg5okMf22/qVCeyY/UfSxXD8aVLF15g=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Cg+bgZeeMUhgypkVyufXcErFqv+HHMEjTCAeFYdEWluBGCAoIceH+iC0y1gOFFIsI SjR8CDAItsGlgIHEg9P89wZDHF4qJzzrBp3z3YjOlrfLc+8g6ffkExyQ6JVHslsh1o xGiQSA0CRdYRCEQMTTTLQoyRLogDkfhy+SULTnE5ydqjr2YroNYsM39PVkjQ33U2tM M/8t6kgMlvLAVxj+vZzgaKZxLx83o78e+S/IuFgyf/EFtGxZQH8+Qum0GklCvNLIwi pXnqRe3oZd1yNf797NhWGrt7iCdL0RdghTWtMY1e5GuuW0pNDomKaPOyLr7HZcvv4k pWIX3knQA0mMQ== Date: Tue, 11 Mar 2025 10:29:28 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: probe-events: Cleanup entry-arg storing code Message-Id: <20250311102928.ae96ceb8870e73e30f6f1279@kernel.org> In-Reply-To: <20250306191404.69b0877e@gandalf.local.home> References: <174099254917.619976.17555764627143910556.stgit@devnote2> <20250306191404.69b0877e@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 6 Mar 2025 19:14:04 -0500 Steven Rostedt wrote: > On Mon, 3 Mar 2025 18:02:29 +0900 > "Masami Hiramatsu (Google)" wrote: > > > + /* Search the offset for the sprcified argnum. */ > > + for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i++) { > > + if (earg->code[i].op != FETCH_OP_ARG || earg->code[i].param != argnum) > > + continue; > > I wonder if you can save a loop by changing this to: > > if (earg->code[i].op != FETCH_OP_ARG) { > last_offset = earg->code[i].offset; > continue; > } > > if (earg->code[i].param != argnum) > continue; > > > > + > > + if (WARN_ON_ONCE(earg->code[i + 1].op != FETCH_OP_ST_EDATA)) > > + continue; > > + > > + return earg->code[i + 1].offset; > > } > > - return -ENOSPC; > > + if (i >= earg->size - 1) > > + return -ENOSPC; > > + > > + /* Not found, append new entry if possible. */ > > + offset = get_entry_arg_max_offset(earg) + sizeof(unsigned long); > > Then here you could use last_offset instead of running the loop again? Yeah, but I would like it easier to read and safer (adding WARN_ON) especially, > if (earg->code[i].op != FETCH_OP_ARG) { > last_offset = earg->code[i].offset; > continue; > } this is a bit unsafe if we introduce another operation except for the FETCH_OP_ARG and FETCH_OP_ST_EDATA. (and it is expecting the offset is always increased.) Thank you, > > -- Steve > > > > + store_entry_arg_at(&earg->code[i], argnum, offset); > > + return offset; > > } > > -- Masami Hiramatsu (Google)