From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 EDAEB156F23; Thu, 16 May 2024 17:46:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715881589; cv=none; b=E8rUSYqJpQpZ6a4GlHh2wc4Ccp8u7UBQOW01NXA5SHTWRHOP/tP+O93lBAeaKCJEsydeLgcP3ub08ESnQOXF1ZztP82+RIIhM2Il6+rBUDSJFrbYM1Oj9EE0Jk+flpoWqjeLf+/KxzP17q9D0Eh+tRzrWzPS2FUjV1SATMg9EXk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715881589; c=relaxed/simple; bh=Pip3wql6yyEL2BrMvPa75zxHMs613XqiPAnva0+Dfu0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EErXFgKz5ZWHJt2iGeT52ky6zQfHga9BMwVlwZyV0Gb1Yc45qr4bR6uikhgB15ypsXrfEziRxIih35WCkArEquTI+m0dwA+FRguO1zUErYFlu/cEndNScdNH/sAYOltWwkSomgB4k0DmPRyFIoxFzgyuIys8u/DrtzNh0ntCKfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Dmh04/mW; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Dmh04/mW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1715881588; x=1747417588; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=Pip3wql6yyEL2BrMvPa75zxHMs613XqiPAnva0+Dfu0=; b=Dmh04/mWZPbR2CIabH5vXK9S5aAj/EruZeLxL585EVk5EeivnVvcvQp6 swDhXGAduSnkYDjCN7C14LFVErueWhknD8AWe6QxWXYZZEYnzkI/6uW1U KbQwitEzzd3YgymnGBLzz+ilMS+biYU9Uh1yNGZMP6UJXl+DMKo/Dkddm +RlPArT/m2XSHAGpLpAFuDYq3kxBz4fPzrDjhUYIazoQPNJV49XfFeDZG K78mDiCxCkYqV+JN9Y/qdrQIBMmoLENA0g4huDscLQFRCsWbq3VQCb6bQ ii4Ig09goi2jxfjfs74mSaHqEyGsX8g/HIKksGoQ3XLPCc0xMVNaEzrna A==; X-CSE-ConnectionGUID: HYhNevZERySCeZYSYwC+aw== X-CSE-MsgGUID: e2K+LT00Sya4JamvZEEQAw== X-IronPort-AV: E=McAfee;i="6600,9927,11074"; a="29533974" X-IronPort-AV: E=Sophos;i="6.08,165,1712646000"; d="scan'208";a="29533974" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 May 2024 10:46:27 -0700 X-CSE-ConnectionGUID: uXhyjaUSSdikXinTg+GxpQ== X-CSE-MsgGUID: uAWpkVS3RR2aBkwFDDbn9w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,165,1712646000"; d="scan'208";a="31650787" Received: from smile.fi.intel.com ([10.237.72.54]) by orviesa009.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 May 2024 10:46:26 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.97) (envelope-from ) id 1s7fBP-000000088AH-1hpF; Thu, 16 May 2024 20:46:23 +0300 Date: Thu, 16 May 2024 20:46:23 +0300 From: Andy Shevchenko To: =?iso-8859-1?Q?N=EDcolas_F=2E_R=2E_A=2E?= Prado Cc: Mark Brown , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 1/1] spi: Remove unneded check for orig_nents Message-ID: References: <20240507201028.564630-1-andriy.shevchenko@linux.intel.com> <2fccdd9a-5b97-4dc6-a6b1-ce2d9e0819bd@notapiano> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2fccdd9a-5b97-4dc6-a6b1-ce2d9e0819bd@notapiano> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Thu, May 16, 2024 at 12:25:19PM -0400, Nícolas F. R. A. Prado wrote: > On Thu, May 16, 2024 at 04:25:35PM +0300, Andy Shevchenko wrote: > > On Thu, May 16, 2024 at 01:18:04PM +0300, Andy Shevchenko wrote: > > > On Wed, May 15, 2024 at 05:09:33PM -0400, Nícolas F. R. A. Prado wrote: > > > > On Tue, May 07, 2024 at 11:10:27PM +0300, Andy Shevchenko wrote: > > > > > Both dma_unmap_sgtable() and sg_free_table() in spi_unmap_buf_attrs() > > > > > have checks for orig_nents against 0. No need to duplicate this. > > > > > All the same applies to other DMA mapping API calls. > > > > > > > > > > Also note, there is no other user in the kernel that does this kind of > > > > > checks. > > > > > > > > > > Signed-off-by: Andy Shevchenko > > > > > > > > this commit caused a regression which I reported here: > > > > > > > > https://lore.kernel.org/all/d3679496-2e4e-4a7c-97ed-f193bd53af1d@notapiano > > > > > > > > along with some thoughts on the cause and a possible solution, though I'm not > > > > familiar with this code base at all and would really appreciate any feedback you > > > > may have. > > > > > > Thanks for the report and preliminary analysis! > > > I'll look at it hopefully sooner than later. > > > > > > But at least what I think now is that my change revealed a problem somewhere > > > else, because that's how DMA mapping / streaming APIs designed, it's extremely > > > rare to check orig_nents field. > > > > Can you test the below patch? > > > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > > index b2efd4964f7c..51811f04e463 100644 > > --- a/drivers/spi/spi.c > > +++ b/drivers/spi/spi.c > > @@ -1243,6 +1243,7 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg) > > else > > rx_dev = ctlr->dev.parent; > > > > + ret = -ENOMSG; > > list_for_each_entry(xfer, &msg->transfers, transfer_list) { > > /* The sync is done before each transfer. */ > > unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC; > > @@ -1272,6 +1273,9 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg) > > } > > } > > } > > + /* No transfer has been mapped, bail out with success */ > > + if (ret) > > + return 0; > > > > ctlr->cur_rx_dma_dev = rx_dev; > > ctlr->cur_tx_dma_dev = tx_dev; > > Hi Andy, > > thank you for the patch. Unfortunately it didn't completely solve the issue. Now > the stack trace is slightly different and points at the next line: > > dma_sync_sgtable_for_device(rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE); > > So now we're hitting the case where only the tx buffer was DMA mapped, but the > rx is still uninitialized, though the cur_msg_mapped flag is set to true, since > it is shared between them. The original code checked for the initialization of > each scatterlist individually, which is why it worked. I was kinda expecting that, and already have another patch to try (should applied on top): diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51811f04e463..5c607dd21fe7 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1258,6 +1258,8 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg) attrs); if (ret != 0) return ret; + } else { + memset(&xfer->tx_sg, 0, sizeof(xfer->tx_sg)); } if (xfer->rx_buf != NULL) { @@ -1271,6 +1273,8 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg) return ret; } + } else { + memset(&xfer->rx_sg, 0, sizeof(xfer->rx_sg)); } } /* No transfer has been mapped, bail out with success */ If my understanding is correct, my patch revealed two issues: - for non-mapped message at all; - for unidirect transfers. But I will wait for your test results to make the final conclusion. -- With Best Regards, Andy Shevchenko