From: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@xxxxxxxxxxx>
This patch fixes the problem that occasionally released resources
before the end of interrupt processing.
[ 58.156412] Unable to handle kernel NULL pointer dereference at virtual
address 00000000
[ 58.166155] pgd = ffff8006f78b0000
[ 58.169822] [00000000] *pgd=000000073773b003 , *pud=0000000737c70003 ,
*pmd=0000000000000000
[ 58.179738]
[ 58.181548] Internal error: Oops: 96000046 [#1] PREEMPT SMP
[ 58.187484] Modules linked in:
[ 58.190919] CPU: 0 PID: 2898 Comm: dma_ioctl Not tainted 4.9.0-00002-g501
07f2-dirty #147
[ 58.199438] Hardware name: Renesas Salvator-X board based on r8a7795 (DT)
[ 58.206680] task: ffff8006f77b1900 task.stack: ffff8006f7bd4000
[ 58.213090] PC is at rcar_dmac_chan_prep_sg+0xa4/0x3f0
[ 58.218725] LR is at rcar_dmac_chan_prep_sg+0x6c/0x3f0
Signed-off-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@xxxxxxxxxxx>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
drivers/dma/sh/rcar-dmac.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 2e441d0..2e0a0d4 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -986,8 +986,11 @@ static void rcar_dmac_free_chan_resources(struct dma_chan *chan)
{
struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
struct rcar_dmac *dmac = to_rcar_dmac(chan->device);
+ struct platform_device *pdev = to_platform_device(dmac->dev);
struct rcar_dmac_desc_page *page, *_page;
struct rcar_dmac_desc *desc;
+ int irq;
+ char pdev_irqname[5];
LIST_HEAD(list);
/* Protect against ISR */
@@ -995,6 +998,14 @@ static void rcar_dmac_free_chan_resources(struct dma_chan *chan)
rcar_dmac_chan_halt(rchan);
spin_unlock_irq(&rchan->lock);
+ sprintf(pdev_irqname, "ch%u", rchan->index);
+ irq = platform_get_irq_byname(pdev, pdev_irqname);
+ if (irq < 0) {
+ dev_err(dmac->dev, "no IRQ specified for channel %u\n",
+ rchan->index);
+ return;
+ }
+ synchronize_irq(irq);
/* Now no new interrupts will occur */
if (rchan->mid_rid >= 0) {
--
1.9.1
