[PATCH v5 2/6] dmaengine: sh: rz-dmac: Move all CHCTRL updates under spinlock

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>

Both rz_dmac_disable_hw() and rz_dmac_irq_handle_channel() update the
CHCTRL registers. To avoid concurrency issues when updating these
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: stable@xxxxxxxxxxxxxxx
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
---

Changes in v5:
- none, this patch is new

 drivers/dma/sh/rz-dmac.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index c8e3d9f77b8a..c013bf30fa5e 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -298,13 +298,10 @@ 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)
@@ -569,8 +566,8 @@ 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;
 
@@ -721,6 +718,8 @@ static irqreturn_t rz_dmac_irq_handler(int irq, void *dev_id)
 {
 	struct rz_dmac_chan *channel = dev_id;
 
+	guard(spinlock)(&channel->vc.lock);
+
 	if (channel) {
 		rz_dmac_irq_handle_channel(channel);
 		return IRQ_WAKE_THREAD;
-- 
2.43.0