MLK-16437: dma: fsl-edma-v3: fix kernel crash while edma interrupt trigger after...

edma interrupt may come after channel terminated, so should ignore
interrupts, else kernel crash as below since fsl_chan->edesc set
to NULL when terminate.

 606.837306] Unable to handle kernel NULL pointer dereference at virtual address 00000060
[  606.845411] pgd = ffff000009295000
[  606.848814] [00000060] *pgd=00000008bfffe003[  606.852906] , *pud=00000008bfffd003
 , *pmd=0000000000000000[  606.858395]
[  606.859885] Internal error: Oops: 96000006 1 PREEMPT SMP
[  606.865460] Modules linked in:
[  606.868522] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.11-03371-g9904ea0 #42
[  606.875832] Hardware name: Freescale i.MX8QXP LPDDR4 ARM2 (DT)
[  606.881662] task: ffff000009120680 task.stack: ffff000009110000
[  606.887588] PC is at fsl_edma3_tx_handler+0x50/0x150

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Tested-by: Daniel Baluta <daniel.baluta@nxp.com>

diff --git a/drivers/dma/fsl-edma-v3.c b/drivers/dma/fsl-edma-v3.c
index 28b13fb..d0aabbc 100644 (file)
--- a/drivers/dma/fsl-edma-v3.c
+++ b/drivers/dma/fsl-edma-v3.c
@@ -689,6 +689,11 @@ static irqreturn_t fsl_edma3_tx_handler(int irq, void *dev_id)
        writel(1, base_addr + EDMA_CH_INT);
 
        spin_lock(&fsl_chan->vchan.lock);
+
+       /* Ignore this interrupt since channel has been disabled already */
+       if (!fsl_chan->edesc)
+               return IRQ_HANDLED;
+
        if (!fsl_chan->edesc->iscyclic) {
                fsl_edma3_get_realcnt(fsl_chan);
                list_del(&fsl_chan->edesc->vdesc.node);