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 X-Spam-Level: X-Spam-Status: No, score=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45686C47088 for ; Wed, 26 May 2021 13:08:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0452761090 for ; Wed, 26 May 2021 13:08:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0452761090 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=walle.cc Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:Cc:To:From :Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vQ3imNoeT9Qn88aiJdlynNVFQQWK8Ul/4SjQsXy3UEc=; b=ER7XA5Z0JDt/2WIRwjofQFkbg/ cDMiISsOoubYQ9/M0ZBndS2YGhVYqtMuRh2mO7mqCGZf814gXLRa930+uE6ALseIpLoVealY6RMuW SS+elUPrB3tMuFZSqCVKGMMCW49PU25OIwijQmXkAeGZlhPjUTdzjAZ7JBNuMBVycEiudfOr3KbHt G9j11NJ1yTzySxjxg5kYN2JC+IVXcZyrepMd5C14ltgCUEnQK8X39lfSeABsUcCsTa5VAa51h6SX4 cSP48klVcHygqF6vzIMt+PP/pSPK/27TaGTwcQ+hSMClRIXZKof8W6sxWFj2Dd+BX1cZhpp6AzMqd uZGjYxpQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lltG4-00EHiB-1a; Wed, 26 May 2021 13:07:36 +0000 Received: from ssl.serverraum.org ([176.9.125.105]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1llqyq-00DGxn-CX for linux-mtd@lists.infradead.org; Wed, 26 May 2021 10:41:42 +0000 Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id C4C7422236; Wed, 26 May 2021 12:41:36 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1622025697; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ErwKEEinBftiXZT6dwCMASUMXD5Y2QAmtSkdKSxxN08=; b=ZhmjZvPFhlGK54bGH1oN+oddaIB/Cw85IIej2dmgiSSSlv1lSNtQh4WqoY0uPbDOMFfKfd onaNwNAGtRJDm45Oqyue4xROpZlR8xJ4GnhvdFsTiBXo0DRIl+9ECvkQM0IxQ7a3t/+Rpr SDmLczovZLTQSgELeFfsbXTPHrNvhaA= MIME-Version: 1.0 Date: Wed, 26 May 2021 12:41:36 +0200 From: Michael Walle To: Pratyush Yadav Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Tudor Ambarus , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra Subject: Re: [PATCH v4 3/4] mtd: spi-nor: otp: return -EROFS if region is read-only In-Reply-To: <20210525193323.xdvbq3tab6oxk6yh@ti.com> References: <20210521194034.15249-1-michael@walle.cc> <20210521194034.15249-4-michael@walle.cc> <20210525193323.xdvbq3tab6oxk6yh@ti.com> User-Agent: Roundcube Webmail/1.4.11 Message-ID: X-Sender: michael@walle.cc X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210526_034140_646425_8457770D X-CRM114-Status: GOOD ( 32.60 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Am 2021-05-25 21:33, schrieb Pratyush Yadav: > On 21/05/21 09:40PM, Michael Walle wrote: >> SPI NOR flashes will just ignore program commands if the OTP region is >> locked. Thus, a user might not notice that the intended write didn't >> end >> up in the flash. Return -EROFS to the user in this case. From what I >> can >> tell, chips/cfi_cmdset_0001.c also return this error code. >> >> One could optimize spi_nor_mtd_otp_range_is_locked() to read the >> status >> register only once and not for every OTP region, but for that we would >> need some more invasive changes. Given that this is >> one-time-programmable memory and the normal access mode is reading, we >> just live with the small overhead. > > Ok. > >> >> Fixes: 069089acf88b ("mtd: spi-nor: add OTP support") >> Signed-off-by: Michael Walle >> --- >> drivers/mtd/spi-nor/otp.c | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c >> index 3898ed67ba1c..b87f96593c13 100644 >> --- a/drivers/mtd/spi-nor/otp.c >> +++ b/drivers/mtd/spi-nor/otp.c >> @@ -249,6 +249,31 @@ static int spi_nor_mtd_otp_info(struct mtd_info >> *mtd, size_t len, >> return ret; >> } >> >> +static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, >> loff_t ofs, >> + size_t len) >> +{ >> + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; >> + unsigned int region; >> + int locked; >> + >> + if (!len) >> + return 0; > > I was inclined to say that the loop conditional below would take care > of > this but it can cause an underflow when ofs and len are both 0. Correct. I didn't want to put an extra check to the caller, because as you noticed, it is checked by the loop there later. >> + >> + /* >> + * If any of the affected OTP regions are locked the entire range is >> + * considered locked. >> + */ >> + for (region = spi_nor_otp_offset_to_region(nor, ofs); >> + region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1); >> + region++) { >> + locked = ops->is_locked(nor, region); >> + if (locked) >> + return locked; >> + } > > Ok. Btw I didn't know if I should put a comment here that this if () handles both locked state and errors. But it seems you've already found out by looking at the caller ;) I'm not sure if this is obvious, though. >> + >> + return 0; >> +} >> + >> static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t >> ofs, >> size_t total_len, size_t *retlen, >> const u8 *buf, bool is_write) >> @@ -271,6 +296,16 @@ static int spi_nor_mtd_otp_read_write(struct >> mtd_info *mtd, loff_t ofs, >> /* don't access beyond the end */ >> total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); >> >> + if (is_write) { >> + ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len); >> + if (ret < 0) { >> + goto out; >> + } else if (ret) { >> + ret = -EROFS; > > I wonder if we should have a dev_info() or dev_err() here. I think this > warrants a dev_dbg() at least. Are you sure? Reporting something to the user via an error code is enough IMHO. I wouldn't want my syslog to be cluttered with messages I already know. I mean the program tell me "hey, you aren't allowed to write there". Why would the kernel still need to tell me that again? Without any connection to the caller, I don't get much out of the kernel message by looking at it alone, just that someone tried to write there. So definetly no dev_info() or dev_err(). But IMHO no dev_dbg() either. Tudor, Vingesh, any opinions? >> + goto out; >> + } > > So it returns -errno when the check for is_locked() fails and 1 or 0 > when it is locked or not. Ok. > > It would be nice if you add a dev_dbg or dev_err() or dev_info() above. > Nonetheless, > > Reviewed-by: Pratyush Yadav Thanks for reviewing! -michael ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/