linux-kernel - [PATCH v2 01/11] dmaengine: dw-edma: Add spinlock to protect DONE_INT_MASK and ABORT_INT

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Message-Id: <20260109-edma_ll-v2-1-5c0b27b2c664@nxp.com>
Date: Fri, 09 Jan 2026 10:28:21 -0500
From: Frank Li <Frank.Li@....com>
To: Manivannan Sadhasivam <mani@...nel.org>, Vinod Koul <vkoul@...nel.org>, 
 Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>, 
 Kees Cook <kees@...nel.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
 Krzysztof Wilczyński <kwilczynski@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, Christoph Hellwig <hch@....de>, 
 Niklas Cassel <cassel@...nel.org>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-hardening@...r.kernel.org, linux-pci@...r.kernel.org, 
 linux-nvme@...ts.infradead.org, imx@...ts.linux.dev, 
 Frank Li <Frank.Li@....com>
Subject: [PATCH v2 01/11] dmaengine: dw-edma: Add spinlock to protect
 DONE_INT_MASK and ABORT_INT_MASK

The DONE_INT_MASK and ABORT_INT_MASK registers are shared by all DMA
channels, and modifying them requires a read-modify-write sequence.
Because this operation is not atomic, concurrent calls to
dw_edma_v0_core_start() can introduce race conditions if two channels
update these registers simultaneously.

Add a spinlock to serialize access to these registers and prevent race
conditions.

Signed-off-by: Frank Li <Frank.Li@....com>
---
vc.lock protect should be another problem. This one just fix register
access for difference DMA channel.

Other improve defer to dynamtic append descriptor works later.
---
 drivers/dma/dw-edma/dw-edma-v0-core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
index b75fdaffad9a4ea6cd8d15e8f43bea550848b46c..2850a9df80f54d00789144415ed2dfe31dea3965 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -364,6 +364,7 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 {
 	struct dw_edma_chan *chan = chunk->chan;
 	struct dw_edma *dw = chan->dw;
+	unsigned long flags;
 	u32 tmp;

 	dw_edma_v0_core_write_chunk(chunk);
@@ -408,6 +409,8 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 			}
 		}
 		/* Interrupt unmask - done, abort */
+		raw_spin_lock_irqsave(&dw->lock, flags);
+
 		tmp = GET_RW_32(dw, chan->dir, int_mask);
 		tmp &= ~FIELD_PREP(EDMA_V0_DONE_INT_MASK, BIT(chan->id));
 		tmp &= ~FIELD_PREP(EDMA_V0_ABORT_INT_MASK, BIT(chan->id));
@@ -416,6 +419,9 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 		tmp = GET_RW_32(dw, chan->dir, linked_list_err_en);
 		tmp |= FIELD_PREP(EDMA_V0_LINKED_LIST_ERR_MASK, BIT(chan->id));
 		SET_RW_32(dw, chan->dir, linked_list_err_en, tmp);
+
+		raw_spin_unlock_irqrestore(&dw->lock, flags);
+
 		/* Channel control */
 		SET_CH_32(dw, chan->dir, chan->id, ch_control1,
 			  (DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));

-- 
2.34.1