From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04BE7C7618B for ; Sat, 18 Mar 2023 17:19:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229978AbjCRRTg (ORCPT ); Sat, 18 Mar 2023 13:19:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229502AbjCRRTe (ORCPT ); Sat, 18 Mar 2023 13:19:34 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B567FE39E; Sat, 18 Mar 2023 10:19:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 70136B806A1; Sat, 18 Mar 2023 17:19:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74683C433D2; Sat, 18 Mar 2023 17:19:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679159970; bh=TlLbFe2AtUWFg73uowAriW9X3Ln7J8/MMonCpaLQ7qw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nufTb8rQPNuar3fPQ0dMH5Hyw3V10Gjszee7hb7wLvSi4HMEM4AKOrAlbY723QHtT dgs2tVBu5NTzPy8C1UQFSgTnHumqLc2Td2TDVIRjk7+uMUh2qU4B4rs3Kilbl0/RjV hgeHeQkQpNycHhjGgtPfOgetWn1e98Y4QviFiJEE/BkAsKdz4RCincWl0TyacvNuel 0olbewnw3DCuIRvLdZadXBxLqiLt9Wl1FoFEOMcc5hswgCrg3vEXd1y3uJD6m6Mf8x JjoIO2oH1yoafj9jNqSWbCi5ridX/xu3BkB9hUKVnHLog8B/4pEHwjeTgdL7+RsWO5 mmm321tY7dzEQ== Date: Sat, 18 Mar 2023 17:34:21 +0000 From: Jonathan Cameron To: James Clark Cc: Krzysztof Kozlowski , linux-kernel@vger.kernel.org, linux@roeck-us.net, michal.simek@amd.com, Jonathan Corbet , Jean Delvare , Anand Ashok Dumbre , Lars-Peter Clausen , Michal Simek , Andy Gross , Bjorn Andersson , Konrad Dybcio , Greg Kroah-Hartman , Jiri Slaby , linux-doc@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH v2 4/4] serial: qcom_geni: Use devm_krealloc_array Message-ID: <20230318173402.20a4f60d@jic23-huawei> In-Reply-To: <74d8b579-6ea8-d6f3-170f-ea13534b4565@arm.com> References: <20230309150334.216760-1-james.clark@arm.com> <20230309150334.216760-5-james.clark@arm.com> <20230311191800.74ec2b84@jic23-huawei> <74d8b579-6ea8-d6f3-170f-ea13534b4565@arm.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.37; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Fri, 17 Mar 2023 11:34:49 +0000 James Clark wrote: > On 11/03/2023 19:18, Jonathan Cameron wrote: > > On Thu, 9 Mar 2023 15:03:33 +0000 > > James Clark wrote: > > > >> Now that it exists, use it instead of doing the multiplication manually. > >> > >> Signed-off-by: James Clark > > > > Hmm. I've stared at the users of this for a bit, and it's not actually obvious > > that it's being used as an array of u32. The only typed user of this is as > > the 2nd parameter of > > tty_insert_flip_string() which is an unsigned char * > > > > I wonder if that sizeof(u32) isn't a 'correct' description of where the 4 is coming > > from even if it has the right value? Perhaps the fifo depth is just a multiple of 4? > > > > Jonathan > > > > The commit that added it (b8caf69a6946) seems to hint that something > reads from it in words. And I see this: > > /* We always configure 4 bytes per FIFO word */ > #define BYTES_PER_FIFO_WORD 4U > > Perhaps sizeof(u32) isn't as accurate of a description as using > BYTES_PER_FIFO_WORD but I'd be reluctant to make a change because I > don't really understand the implications. Agreed with your analysis. + fully understand why you don't want to change it. I'd be tempted to take the view that whilst it's allocated in 4 byte chunks because it's accessed elsewhere as a set of 1 byte entries, krealloc_array isn't appropriate and so just leave it with devm_krealloc() Risk is that a steady stream of patches will turn up 'fixing' this as it will be easy for people to find with a script. Maybe better to just add a comment (either with or without your patch). > > There is also this in handle_rx_console(): > > unsigned char buf[sizeof(u32)]; > > James > > > > > > >> --- > >> drivers/tty/serial/qcom_geni_serial.c | 6 +++--- > >> 1 file changed, 3 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c > >> index d69592e5e2ec..23fc33d182ac 100644 > >> --- a/drivers/tty/serial/qcom_geni_serial.c > >> +++ b/drivers/tty/serial/qcom_geni_serial.c > >> @@ -1056,9 +1056,9 @@ static int setup_fifos(struct qcom_geni_serial_port *port) > >> (port->tx_fifo_depth * port->tx_fifo_width) / BITS_PER_BYTE; > >> > >> if (port->rx_buf && (old_rx_fifo_depth != port->rx_fifo_depth) && port->rx_fifo_depth) { > >> - port->rx_buf = devm_krealloc(uport->dev, port->rx_buf, > >> - port->rx_fifo_depth * sizeof(u32), > >> - GFP_KERNEL); > >> + port->rx_buf = devm_krealloc_array(uport->dev, port->rx_buf, > >> + port->rx_fifo_depth, sizeof(u32), > >> + GFP_KERNEL); > >> if (!port->rx_buf) > >> return -ENOMEM; > >> } > >