Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933064AbbLWGPJ (ORCPT ); Wed, 23 Dec 2015 01:15:09 -0500 Received: from mga14.intel.com ([192.55.52.115]:64987 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754803AbbLWGOV (ORCPT ); Wed, 23 Dec 2015 01:14:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,467,1444719600"; d="scan'208";a="622601394" From: Ashutosh Dixit To: Saurabh Sengar Cc: "Koul\, Vinod" , "linux-kernel\@vger.kernel.org" , "dmaengine\@vger.kernel.org" , "Dutt\, Sudeep" , "Rao\, Nikhil" , Siva Yerramreddy Subject: Re: [PATCH] dma: Revert "dmaengine: mic_x100: add missing spin_unlock" References: <1450841723-6227-1-git-send-email-ashutosh.dixit@intel.com> Date: Wed, 23 Dec 2015 01:14:20 -0500 In-Reply-To: (Saurabh Sengar's message of "Tue, 22 Dec 2015 22:45:31 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3151 Lines: 89 On Wed, Dec 23 2015 at 12:45:31 AM, Saurabh Sengar wrote: > On 23 December 2015 at 09:05, Ashutosh Dixit wrote: >> This reverts commit e958e079e254 ("dmaengine: mic_x100: add missing >> spin_unlock"). >> >> The above patch is incorrect. There is nothing wrong with the original >> code. The spin_lock is acquired in the "prep" functions and released >> in "submit". > > Hi Ashutosh, > > If it is need to be released by submit function, we don't require the > spin_unlock on success case as well. > am I correct ? No, you are wrong. In the prep functions, we are not using spin_unlock in success cases but in failure ones. >> Signed-off-by: Ashutosh Dixit >> --- >> drivers/dma/mic_x100_dma.c | 15 +++++---------- >> 1 file changed, 5 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/dma/mic_x100_dma.c b/drivers/dma/mic_x100_dma.c >> index cddfa8d..068e920 100644 >> --- a/drivers/dma/mic_x100_dma.c >> +++ b/drivers/dma/mic_x100_dma.c >> @@ -317,7 +317,6 @@ mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest, >> struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch); >> struct device *dev = mic_dma_ch_to_device(mic_ch); >> int result; >> - struct dma_async_tx_descriptor *tx = NULL; >> >> if (!len && !flags) >> return NULL; >> @@ -325,13 +324,10 @@ mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest, >> spin_lock(&mic_ch->prep_lock); >> result = mic_dma_do_dma(mic_ch, flags, dma_src, dma_dest, len); >> if (result >= 0) >> - tx = allocate_tx(mic_ch); >> - >> - if (!tx) >> - dev_err(dev, "Error enqueueing dma, error=%d\n", result); >> - >> + return allocate_tx(mic_ch); >> + dev_err(dev, "Error enqueueing dma, error=%d\n", result); >> spin_unlock(&mic_ch->prep_lock); > > This spin_unlock shouldn't be required as explained it is getting > released by submit function This is a failure case. Submit will not be called in this case so spin_unlock needs to be called here. >> - return tx; >> + return NULL; >> } >> >> static struct dma_async_tx_descriptor * >> @@ -339,14 +335,13 @@ mic_dma_prep_interrupt_lock(struct dma_chan *ch, unsigned long flags) >> { >> struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch); >> int ret; >> - struct dma_async_tx_descriptor *tx = NULL; >> >> spin_lock(&mic_ch->prep_lock); >> ret = mic_dma_do_dma(mic_ch, flags, 0, 0, 0); >> if (!ret) >> - tx = allocate_tx(mic_ch); >> + return allocate_tx(mic_ch); >> spin_unlock(&mic_ch->prep_lock); > > and this too ? Yes, this too. >> - return tx; >> + return NULL; >> } >> >> /* Return the status of the transaction */ >> -- >> 2.0.0.rc3.2.g998f840 >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/