From nobody Fri Sep 20 11:44:41 2024 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DE0DC04A6A for ; Sun, 6 Aug 2023 03:25:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229516AbjHFDZq (ORCPT ); Sat, 5 Aug 2023 23:25:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbjHFDZo (ORCPT ); Sat, 5 Aug 2023 23:25:44 -0400 Received: from zg8tndyumtaxlji0oc4xnzya.icoremail.net (zg8tndyumtaxlji0oc4xnzya.icoremail.net [46.101.248.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F407F1FE4; Sat, 5 Aug 2023 20:25:39 -0700 (PDT) Received: from ubuntu.localdomain (unknown [218.12.19.97]) by mail-app4 (Coremail) with SMTP id cS_KCgCnrBSYEs9kXASjCg--.63926S2; Sun, 06 Aug 2023 11:25:21 +0800 (CST) From: Duoming Zhou To: sean.wang@mediatek.com Cc: vkoul@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, Duoming Zhou Subject: [PATCH] dmaengine: mediatek: Fix deadlock caused by synchronize_irq() Date: Sun, 6 Aug 2023 11:25:11 +0800 Message-Id: <20230806032511.45263-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: cS_KCgCnrBSYEs9kXASjCg--.63926S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Zryxuw4rJF4ktw1UtrWfGrg_yoW8GFy3pF WDJa45CFWqyr1Dua1UCr42qFWrC3WfGrW7Gr4fXw43Ca4rJryYvr1FyayavF4jqr9rKa97 Kr4UtrWrCF4jyr7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUym14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij64vI r41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8Gjc xK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0 cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8V AvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E 14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUdHUDUUUUU= X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAwQSAWTNp-sHcgAhs1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- 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/m= tk-uart-apdma.c index a1517ef1f4a..0acf6a92a4a 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); =20 - synchronize_irq(c->irq); - spin_unlock_irqrestore(&c->vc.lock, flags); + synchronize_irq(c->irq); =20 return 0; } --=20 2.17.1