From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 140D21944F for ; Mon, 16 Oct 2023 08:51:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vPdaRdcc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0969BC433C7; Mon, 16 Oct 2023 08:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697446272; bh=X3AoZ/Ib7EGx0gj3QsuUKnFdHJPbrv+K4/5x3WPSV8Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vPdaRdccB8WqDC1PDoZmc2R9g0YGfR4TBf+kY6ZfQRobhJyjXFUKWFjytjD+0LSjU SHieWiBObOxB2MsYNEDoNn+7JJ6nZ4KHdgUWhwbP/7ggTIlV3eHofBK6htiqsN+PIa C61S9I9Vpg0wilu7jXvJ3c2umYZm7+vmJUmDlbN8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Duoming Zhou , Eugen Hristev , Vinod Koul , Sasha Levin Subject: [PATCH 5.15 082/102] dmaengine: mediatek: Fix deadlock caused by synchronize_irq() Date: Mon, 16 Oct 2023 10:41:21 +0200 Message-ID: <20231016083955.880797164@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231016083953.689300946@linuxfoundation.org> References: <20231016083953.689300946@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Duoming Zhou [ Upstream commit 01f1ae2733e2bb4de92fefcea5fda847d92aede1 ] The synchronize_irq(c->irq) will not return until the IRQ handler mtk_uart_apdma_irq_handler() is completed. If the synchronize_irq() holds a spin_lock and waits the IRQ handler to complete, but the IRQ handler also needs the same spin_lock. The deadlock will happen. The process is shown below: cpu0 cpu1 mtk_uart_apdma_device_pause() | mtk_uart_apdma_irq_handler() spin_lock_irqsave() | | spin_lock_irqsave() //hold the lock to wait | synchronize_irq() | This patch reorders the synchronize_irq(c->irq) outside the spin_lock in order to mitigate the bug. Fixes: 9135408c3ace ("dmaengine: mediatek: Add MediaTek UART APDMA support") Signed-off-by: Duoming Zhou Reviewed-by: Eugen Hristev Link: https://lore.kernel.org/r/20230806032511.45263-1-duoming@zju.edu.cn Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/mediatek/mtk-uart-apdma.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c index a1517ef1f4a01..0acf6a92a4ad3 100644 --- a/drivers/dma/mediatek/mtk-uart-apdma.c +++ b/drivers/dma/mediatek/mtk-uart-apdma.c @@ -451,9 +451,8 @@ static int mtk_uart_apdma_device_pause(struct dma_chan *chan) mtk_uart_apdma_write(c, VFF_EN, VFF_EN_CLR_B); mtk_uart_apdma_write(c, VFF_INT_EN, VFF_INT_EN_CLR_B); - synchronize_irq(c->irq); - spin_unlock_irqrestore(&c->vc.lock, flags); + synchronize_irq(c->irq); return 0; } -- 2.40.1