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Fri, 06 Jun 2025 00:42:15 -0700 (PDT) Message-ID: Date: Fri, 6 Jun 2025 10:42:11 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] dmaengine: mediatek: Fix a flag reuse error in mtk_cqdma_tx_status() To: Qiu-ji Chen , sean.wang@mediatek.com, vkoul@kernel.org, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com Cc: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, stable@vger.kernel.org, kernel test robot References: <20250606071709.4738-1-chenqiuji666@gmail.com> Content-Language: en-US From: Eugen Hristev In-Reply-To: <20250606071709.4738-1-chenqiuji666@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/6/25 10:17, Qiu-ji Chen wrote: > Fixed a flag reuse bug in the mtk_cqdma_tx_status() function. > > Fixes: 157ae5ffd76a ("dmaengine: mediatek: Fix a possible deadlock error in mtk_cqdma_tx_status()") > Cc: stable@vger.kernel.org > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202505270641.MStzJUfU-lkp@intel.com/ > Signed-off-by: Qiu-ji Chen > --- > drivers/dma/mediatek/mtk-cqdma.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/drivers/dma/mediatek/mtk-cqdma.c b/drivers/dma/mediatek/mtk-cqdma.c > index 47c8adfdc155..f7b870d2ca90 100644 > --- a/drivers/dma/mediatek/mtk-cqdma.c > +++ b/drivers/dma/mediatek/mtk-cqdma.c > @@ -441,18 +441,19 @@ static enum dma_status mtk_cqdma_tx_status(struct dma_chan *c, > struct mtk_cqdma_vdesc *cvd; > struct virt_dma_desc *vd; > enum dma_status ret; > - unsigned long flags; > + unsigned long pc_flags; > + unsigned long vc_flags; > size_t bytes = 0; > > ret = dma_cookie_status(c, cookie, txstate); > if (ret == DMA_COMPLETE || !txstate) > return ret; > > - spin_lock_irqsave(&cvc->pc->lock, flags); > - spin_lock_irqsave(&cvc->vc.lock, flags); > + spin_lock_irqsave(&cvc->pc->lock, pc_flags); > + spin_lock_irqsave(&cvc->vc.lock, vc_flags); > vd = mtk_cqdma_find_active_desc(c, cookie); > - spin_unlock_irqrestore(&cvc->vc.lock, flags); > - spin_unlock_irqrestore(&cvc->pc->lock, flags); > + spin_unlock_irqrestore(&cvc->vc.lock, vc_flags); > + spin_unlock_irqrestore(&cvc->pc->lock, pc_flags); > > if (vd) { > cvd = to_cqdma_vdesc(vd); If the first spin_lock_irqsave already saved the irq flags and disabled them, would it be meaningful to actually use a simple spin_lock for the second lock ? Or rather spin_lock_nested since there is a second nested lock taken ? Eugen