From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 616F93AFB11; Wed, 30 Sep 2026 16:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785947; cv=none; b=cVFtiwy1pUskzplRGj3ABBHCTnTFhTrDoL4p92Y6zn6pxtEpTqSXF4KHgrBIduza2uw2RLPaULu4oBsW6n9GKHSwVA4x3Crcha9ippZykEXXUbR0pqpqsskPoFUZqG1u2vM0gJB3NceyIr60ya8pOPbr1JV013PcGWp3Mr0TTGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785947; c=relaxed/simple; bh=xh0RRzuxQyMGmloDwiEBd5Ad9SxZXmaKDE5biQKSsNM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ar65mA3xJdeke9ZzgGem2a0G8JYogdUV8tI03e8uyNy/U93hr9sD9W7bc4z/xgObp36EOBGsnqwHiFG+iuA0fj8HrFWlZaooSQDmlaqlk+U2TBeFaAZYuehyw49gvfT9N47I6v4n96OqyPSk5njop0tZ8UHVQFGKHpTtz+hpPRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EuJhjdHB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EuJhjdHB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB9081F000FF; Wed, 30 Sep 2026 16:32:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790785946; bh=iv8nnMMZGjgAO90e6NqJFrTr5xDFvnv86HrcspIuxbI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EuJhjdHBSCmS3fdTMAransUABK/bUNc22Ou9kM2nJewmqLmJcTVg2MM0nuzyIQQI5 d/X81KEzCOizSh2GklMTTt4JS/UN7U3sDhlI4KxYzOO3aN5JgAHsyoAYc1sR4v5rta 4FQ93fy52LXM+mHG1LGez+zFtu44DGAw3N3r/3Ys= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alex Bereza , Frank Li , Suraj Gupta , Vinod Koul , Sasha Levin Subject: [PATCH 6.1 643/982] dmaengine: xilinx_dma: Fix hardware buffer descriptor reuse order Date: Wed, 30 Sep 2026 17:22:59 +0200 Message-ID: <20260930152430.577853774@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Bereza [ Upstream commit cee9c863ee68cb27d66745eb03f60e357f4f8ad2 ] xilinx_dma_alloc_chan_resources() builds a static ring of hardware buffer descriptors once and the driver uses this ring throughout the lifetime of a channel. This requires the allocation order of hardware buffer descriptors from chan->free_seg_list to stay in sync with the hardware buffer descriptor ring built at channel allocation time by returning oldest descriptors to chan->free_seg_list first. When chan->pending_list is not empty e.g. during xilinx_dma_terminate_all() the chan->free_seg_list and the order of the static hardware buffer descriptor ring get out of sync. Descriptors age in this order: pending -> active -> done. So freeing pending_list first returns the newest buffer descriptors to the chan->free_seg_list first and thus breaks the order required by the static hardware buffer descriptor ring. Then when the channel is reused, after a wrap around of the free_seg_list the DMA will find a hardware buffer descriptor with a length field that is still zeroed and stop with something like this: xilinx-vdma 86000000.dma: Channel 000000003a21d7b8 has errors 10, cdr 6de4c000 tdr 6de4c000 After this no more descriptors are completed and a consumer potentially blocks and waits forever. The only way to get out of this error state is to rebuild the static hardware buffer descriptor ring and the free_seg_list by releasing and re-acquiring the channel. Fix the order in which hardware buffer descriptors are returned to free_seg_list to ensure the mentioned requirement holds. Fixes: 23059408b6a3 ("dmaengine: xilinx_dma: Fix race condition in the driver for multiple descriptor scenario") Signed-off-by: Alex Bereza Reviewed-by: Frank Li Reviewed-by: Suraj Gupta Link: https://patch.msgid.link/20260817-fix-hw-buf-desc-reuse-v1-1-d79827a844c7@bereza.email Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/xilinx/xilinx_dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c index 914399ba74935..53e791513b7e0 100644 --- a/drivers/dma/xilinx/xilinx_dma.c +++ b/drivers/dma/xilinx/xilinx_dma.c @@ -889,9 +889,9 @@ static void xilinx_dma_free_descriptors(struct xilinx_dma_chan *chan) spin_lock_irqsave(&chan->lock, flags); - xilinx_dma_free_desc_list(chan, &chan->pending_list); xilinx_dma_free_desc_list(chan, &chan->done_list); xilinx_dma_free_desc_list(chan, &chan->active_list); + xilinx_dma_free_desc_list(chan, &chan->pending_list); spin_unlock_irqrestore(&chan->lock, flags); } -- 2.53.0