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FAILED: patch "[PATCH] dmaengine: sh: rz-dmac: Move CHCTRL updates under spinlock" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 2 messages Mar 30 – Apr 1

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author maintainer
#0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 89a8567d84bde88cb7cdbbac2ab2299c4f991490
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026033044-applause-erased-d411@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 89a8567d84bde88cb7cdbbac2ab2299c4f991490 Mon Sep 17 00:00:00 2001
From: Claudiu Beznea <[email protected]>
Date: Mon, 16 Mar 2026 15:32:46 +0200
Subject: [PATCH] dmaengine: sh: rz-dmac: Move CHCTRL updates under spinlock

Both rz_dmac_disable_hw() and rz_dmac_irq_handle_channel() update the CHCTRL register. To avoid concurrency issues when configuring functionalities exposed by this registers, take the virtual channel lock. All other CHCTRL updates were already protected by the same lock.

Previously, rz_dmac_disable_hw() disabled and re-enabled local IRQs, before accessing CHCTRL registers but this does not ensure race-free access. Remove the local IRQ disable/enable code as well.

Fixes 5000d37042a6 ("dmaengine: sh: Add DMAC driver for RZ/G2L SoC")
Cc [email protected]
Reviewed-by Biju Das <[email protected]>
Reviewed-by Frank Li <[email protected]>
Signed-off-by Claudiu Beznea <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Vinod Koul <[email protected]>
drivers/dma/sh/rz-dmac.c +4 -5
index 089e1ab29159..f30bdf69c740 100644
@@ -297,13 +297,10 @@ static void rz_dmac_disable_hw(struct rz_dmac_chan *channel)
 {
 	struct dma_chan *chan = &channel->vc.chan;
 	struct rz_dmac *dmac = to_rz_dmac(chan->device);
-	unsigned long flags;
 
 	dev_dbg(dmac->dev, "%s channel %d\n", __func__, channel->index);
 
-	local_irq_save(flags);
 	rz_dmac_ch_writel(channel, CHCTRL_DEFAULT, CHCTRL, 1);
-	local_irq_restore(flags);
 }
 
 static void rz_dmac_set_dmars_register(struct rz_dmac *dmac, int nr, u32 dmars)

@@ -568,8 +565,8 @@ static int rz_dmac_terminate_all(struct dma_chan *chan)
 	unsigned int i;
 	LIST_HEAD(head);
 
-	rz_dmac_disable_hw(channel);
 	spin_lock_irqsave(&channel->vc.lock, flags);
+	rz_dmac_disable_hw(channel);
 	for (i = 0; i < DMAC_NR_LMDESC; i++)
 		lmdesc[i].header = 0;
 

@@ -706,7 +703,9 @@ static void rz_dmac_irq_handle_channel(struct rz_dmac_chan *channel)
 	if (chstat & CHSTAT_ER) {
 		dev_err(dmac->dev, "DMAC err CHSTAT_%d = %08X\n",
 			channel->index, chstat);
-		rz_dmac_ch_writel(channel, CHCTRL_DEFAULT, CHCTRL, 1);
+
+		scoped_guard(spinlock_irqsave, &channel->vc.lock)
+			rz_dmac_ch_writel(channel, CHCTRL_DEFAULT, CHCTRL, 1);
 		goto done;
 	}
maintainer
#1 lore raw

PATCH 1/1 dmaengine: sh: rz-dmac: Move CHCTRL updates under spinlock

From: Claudiu Beznea <[email protected]>

[ Upstream commit 89a8567d84bde88cb7cdbbac2ab2299c4f991490 ]

Both rz_dmac_disable_hw() and rz_dmac_irq_handle_channel() update the CHCTRL register. To avoid concurrency issues when configuring functionalities exposed by this registers, take the virtual channel lock. All other CHCTRL updates were already protected by the same lock.

Previously, rz_dmac_disable_hw() disabled and re-enabled local IRQs, before accessing CHCTRL registers but this does not ensure race-free access. Remove the local IRQ disable/enable code as well.

Fixes 5000d37042a6 ("dmaengine: sh: Add DMAC driver for RZ/G2L SoC")
Cc [email protected]
Reviewed-by Biju Das <[email protected]>
Reviewed-by Frank Li <[email protected]>
Signed-off-by Claudiu Beznea <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Vinod Koul <[email protected]>
[ replaced scoped_guard(spinlock_irqsave, ...) ]
Signed-off-by Sasha Levin <[email protected]>
---
 drivers/dma/sh/rz-dmac.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
drivers/dma/sh/rz-dmac.c +5 -4
index e6f8257c76672..acab58b02dbe9 100644
@@ -283,13 +283,10 @@ static void rz_dmac_disable_hw(struct rz_dmac_chan *channel)
 {
 	struct dma_chan *chan = &channel->vc.chan;
 	struct rz_dmac *dmac = to_rz_dmac(chan->device);
-	unsigned long flags;
 
 	dev_dbg(dmac->dev, "%s channel %d\n", __func__, channel->index);
 
-	local_irq_save(flags);
 	rz_dmac_ch_writel(channel, CHCTRL_DEFAULT, CHCTRL, 1);
-	local_irq_restore(flags);
 }
 
 static void rz_dmac_set_dmars_register(struct rz_dmac *dmac, int nr, u32 dmars)

@@ -536,8 +533,8 @@ static int rz_dmac_terminate_all(struct dma_chan *chan)
 	unsigned int i;
 	LIST_HEAD(head);
 
-	rz_dmac_disable_hw(channel);
 	spin_lock_irqsave(&channel->vc.lock, flags);
+	rz_dmac_disable_hw(channel);
 	for (i = 0; i < DMAC_NR_LMDESC; i++)
 		lmdesc[i].header = 0;
 

@@ -646,13 +643,17 @@ static void rz_dmac_irq_handle_channel(struct rz_dmac_chan *channel)
 {
 	struct dma_chan *chan = &channel->vc.chan;
 	struct rz_dmac *dmac = to_rz_dmac(chan->device);
+	unsigned long flags;
 	u32 chstat, chctrl;
 
 	chstat = rz_dmac_ch_readl(channel, CHSTAT, 1);
 	if (chstat & CHSTAT_ER) {
 		dev_err(dmac->dev, "DMAC err CHSTAT_%d = %08X\n",
 			channel->index, chstat);
+
+		spin_lock_irqsave(&channel->vc.lock, flags);
 		rz_dmac_ch_writel(channel, CHCTRL_DEFAULT, CHCTRL, 1);
+		spin_unlock_irqrestore(&channel->vc.lock, flags);
 		goto done;
 	}
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2.53.0