From: Hiroyuki Yokoyama <[email protected]> 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 <[email protected]> Signed-off-by: Yoshihiro Shimoda <[email protected]> --- 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
