[PATCH v4 01/17] dmaengine: sh: rz-dmac: Move interrupt request after everything is set up

Claudiu
2026-04-11T11:43:11Z

Once the interrupt is requested, the interrupt handler may run immediately.
Since the IRQ handler can access channel->ch_base, which is initialized
only after requesting the IRQ, this may lead to invalid memory access.
Likewise, the IRQ thread may access uninitialized data (the ld_free,
ld_queue, and ld_active lists), which may also lead to issues.

Request the interrupts only after everything is set up. To keep the error
path simpler, use dmam_alloc_coherent() instead of dma_alloc_coherent().

Fixes: 5000d37042a6 ("dmaengine: sh: Add DMAC driver for RZ/G2L SoC")
Cc: stable@vger.kernel.org
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v4:
- none, this patch is new

drivers/dma/sh/rz-dmac.c | 88 +++++++++++++++-------------------------
1 file changed, 33 insertions(+), 55 deletions(-)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index 625ff29024de..9f206a33dcc6 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -981,25 +981,6 @@ static int rz_dmac_chan_probe(struct rz_dmac *dmac,
channel->index = index;
channel->mid_rid = -EINVAL;

- /* Request the channel interrupt. */
- scnprintf(pdev_irqname, sizeof(pdev_irqname), "ch%u", index);
- irq = platform_get_irq_byname(pdev, pdev_irqname);
- if (irq < 0)
- return irq;
-
- irqname = devm_kasprintf(dmac->dev, GFP_KERNEL, "%s:%u",
- dev_name(dmac->dev), index);
- if (!irqname)
- return -ENOMEM;
-
- ret = devm_request_threaded_irq(dmac->dev, irq, rz_dmac_irq_handler,
- rz_dmac_irq_handler_thread, 0,
- irqname, channel);
- if (ret) {
- dev_err(dmac->dev, "failed to request IRQ %u (%d)\n", irq, ret);
- return ret;
- }
-
/* Set io base address for each channel */
if (index < 8) {
channel->ch_base = dmac->base + CHANNEL_0_7_OFFSET +
@@ -1012,9 +993,9 @@ static int rz_dmac_chan_probe(struct rz_dmac *dmac,
}

/* Allocate descriptors */
- lmdesc = dma_alloc_coherent(&pdev->dev,
- sizeof(struct rz_lmdesc) * DMAC_NR_LMDESC,
- &channel->lmdesc.base_dma, GFP_KERNEL);
+ lmdesc = dmam_alloc_coherent(&pdev->dev,
+ sizeof(struct rz_lmdesc) * DMAC_NR_LMDESC,
+ &channel->lmdesc.base_dma, GFP_KERNEL);
if (!lmdesc) {
dev_err(&pdev->dev, "Can't allocate memory (lmdesc)\n");
return -ENOMEM;
@@ -1030,7 +1011,24 @@ static int rz_dmac_chan_probe(struct rz_dmac *dmac,
INIT_LIST_HEAD(&channel->ld_free);
INIT_LIST_HEAD(&channel->ld_active);

- return 0;
+ /* Request the channel interrupt. */
+ scnprintf(pdev_irqname, sizeof(pdev_irqname), "ch%u", index);
+ irq = platform_get_irq_byname(pdev, pdev_irqname);
+ if (irq < 0)
+ return irq;
+
+ irqname = devm_kasprintf(dmac->dev, GFP_KERNEL, "%s:%u",
+ dev_name(dmac->dev), index);
+ if (!irqname)
+ return -ENOMEM;
+
+ ret = devm_request_threaded_irq(dmac->dev, irq, rz_dmac_irq_handler,
+ rz_dmac_irq_handler_thread, 0,
+ irqname, channel);
+ if (ret)
+ dev_err(dmac->dev, "failed to request IRQ %u (%d)\n", irq, ret);
+
+ return ret;
}

static void rz_dmac_put_device(void *_dev)
@@ -1099,7 +1097,6 @@ static int rz_dmac_probe(struct platform_device *pdev)
const char *irqname = "error";
struct dma_device *engine;
struct rz_dmac *dmac;
- int channel_num;
int ret;
int irq;
u8 i;
@@ -1132,18 +1129,6 @@ static int rz_dmac_probe(struct platform_device *pdev)
return PTR_ERR(dmac->ext_base);
}

- /* Register interrupt handler for error */
- irq = platform_get_irq_byname_optional(pdev, irqname);
- if (irq > 0) {
- ret = devm_request_irq(&pdev->dev, irq, rz_dmac_irq_handler, 0,
- irqname, NULL);
- if (ret) {
- dev_err(&pdev->dev, "failed to request IRQ %u (%d)\n",
- irq, ret);
- return ret;
- }
- }
-
/* Initialize the channels. */
INIT_LIST_HEAD(&dmac->engine.channels);

@@ -1169,6 +1154,18 @@ static int rz_dmac_probe(struct platform_device *pdev)
goto err;
}

+ /* Register interrupt handler for error */
+ irq = platform_get_irq_byname_optional(pdev, irqname);
+ if (irq > 0) {
+ ret = devm_request_irq(&pdev->dev, irq, rz_dmac_irq_handler, 0,
+ irqname, NULL);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to request IRQ %u (%d)\n",
+ irq, ret);
+ goto err;
+ }
+ }
+
/* Register the DMAC as a DMA provider for DT. */
ret = of_dma_controller_register(pdev->dev.of_node, rz_dmac_of_xlate,
NULL);
@@ -1210,16 +1207,6 @@ static int rz_dmac_probe(struct platform_device *pdev)
dma_register_err:
of_dma_controller_free(pdev->dev.of_node);
err:
- channel_num = i ? i - 1 : 0;
- for (i = 0; i < channel_num; i++) {
- struct rz_dmac_chan *channel = &dmac->channels[i];
-
- dma_free_coherent(&pdev->dev,
- sizeof(struct rz_lmdesc) * DMAC_NR_LMDESC,
- channel->lmdesc.base,
- channel->lmdesc.base_dma);
- }
-
reset_control_assert(dmac->rstc);
err_pm_runtime_put:
pm_runtime_put(&pdev->dev);
@@ -1232,18 +1219,9 @@ static int rz_dmac_probe(struct platform_device *pdev)
static void rz_dmac_remove(struct platform_device *pdev)
{
struct rz_dmac *dmac = platform_get_drvdata(pdev);
- unsigned int i;

dma_async_device_unregister(&dmac->engine);
of_dma_controller_free(pdev->dev.of_node);
- for (i = 0; i < dmac->n_channels; i++) {
- struct rz_dmac_chan *channel = &dmac->channels[i];
-
- dma_free_coherent(&pdev->dev,
- sizeof(struct rz_lmdesc) * DMAC_NR_LMDESC,
- channel->lmdesc.base,
- channel->lmdesc.base_dma);
- }
reset_control_assert(dmac->rstc);
pm_runtime_put(&pdev->dev);
pm_runtime_disable(&pdev->dev);
--
2.43.0