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Wed, 23 Sep 2026 02:44:34 -0700 (PDT) Received: from localhost.localdomain ([2406:da14:10b4:9b00:211e:3d68:8776:5ca0]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df6a60c741sm7874725ad.80.2026.09.23.02.44.31 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 23 Sep 2026 02:44:34 -0700 (PDT) From: Ginger Li To: sean.wang@mediatek.com Cc: vkoul@kernel.org, Frank.Li@kernel.org, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] dmaengine: milbeaut-hdmac: Fix deadlock with the channel IRQ handler Date: Wed, 23 Sep 2026 17:44:26 +0800 Message-ID: <20260923094426.67872-1-ginger.jzllee@gmail.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit milbeaut_hdmac_interrupt() is a hardirq handler and takes mc->vc.lock with a plain spin_lock() for the whole time it runs. interrupts are disabled locally in that context, so the handler itself is fine. milbeaut_hdmac_chan_config(), milbeaut_hdmac_chan_pause() and milbeaut_hdmac_chan_resume() are called from process context and take the same lock with a plain spin_lock() as well, so interrupts stay enabled while the lock is held. If a channel interrupt is delivered on the CPU that is inside one of those critical sections, milbeaut_hdmac_interrupt() spins on a lock that the interrupted code is holding and can never release, and the CPU hangs. Take mc->vc.lock with spin_lock_irqsave() in those three functions, as milbeaut_hdmac_issue_pending() and the other process context users of this lock already do. Fixes: 6c3214e698e4 ("dmaengine: milbeaut-hdmac: Add HDMAC driver for Milbeaut platforms") Signed-off-by: Ginger Li --- drivers/dma/milbeaut-hdmac.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/dma/milbeaut-hdmac.c b/drivers/dma/milbeaut-hdmac.c --- a/drivers/dma/milbeaut-hdmac.c +++ b/drivers/dma/milbeaut-hdmac.c @@ -214,10 +214,11 @@ milbeaut_hdmac_chan_config(struct dma_chan *chan, stru { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); mc->cfg = *cfg; - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; } @@ -226,13 +227,14 @@ static int milbeaut_hdmac_chan_pause(struct dma_chan * { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; u32 val; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); val = readl_relaxed(mc->reg_ch_base + MLB_HDMAC_DMACA); val |= MLB_HDMAC_PB; writel_relaxed(val, mc->reg_ch_base + MLB_HDMAC_DMACA); - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; } @@ -241,13 +243,14 @@ static int milbeaut_hdmac_chan_resume(struct dma_chan { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; u32 val; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); val = readl_relaxed(mc->reg_ch_base + MLB_HDMAC_DMACA); val &= ~MLB_HDMAC_PB; writel_relaxed(val, mc->reg_ch_base + MLB_HDMAC_DMACA); - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; } -- 2.43.0