blob: b2ee04103f544a646bcb122190305de6ce215de8 [file] [log] [blame]
From 56028ee9a0b668d0c3aa416dea5d70fcb7817b34 Mon Sep 17 00:00:00 2001
From: John Stultz <john.stultz@linaro.org>
Date: Wed, 18 Dec 2019 19:09:06 +0000
Subject: [PATCH] dmaengine: k3dma: Avoid null pointer traversal
commit 2f42e05b942fe2fbfb9bbc6e34e1dd8c3ce4f3a4 upstream.
In some cases we seem to submit two transactions in a row, which
causes us to lose track of the first. If we then cancel the
request, we may still get an interrupt, which traverses a null
ds_run value.
So try to avoid starting a new transaction if the ds_run value
is set.
While this patch avoids the null pointer crash, I've had some
reports of the k3dma driver still getting confused, which
suggests the ds_run/ds_done value handling still isn't quite
right. However, I've not run into an issue recently with it
so I think this patch is worth pushing upstream to avoid the
crash.
Signed-off-by: John Stultz <john.stultz@linaro.org>
[add ss tag]
Link: https://lore.kernel.org/r/20191218190906.6641-1-john.stultz@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/dma/k3dma.c b/drivers/dma/k3dma.c
index 4b36c8810517..d05471653224 100644
--- a/drivers/dma/k3dma.c
+++ b/drivers/dma/k3dma.c
@@ -229,9 +229,11 @@ static irqreturn_t k3_dma_int_handler(int irq, void *dev_id)
c = p->vchan;
if (c && (tc1 & BIT(i))) {
spin_lock_irqsave(&c->vc.lock, flags);
- vchan_cookie_complete(&p->ds_run->vd);
- p->ds_done = p->ds_run;
- p->ds_run = NULL;
+ if (p->ds_run != NULL) {
+ vchan_cookie_complete(&p->ds_run->vd);
+ p->ds_done = p->ds_run;
+ p->ds_run = NULL;
+ }
spin_unlock_irqrestore(&c->vc.lock, flags);
}
if (c && (tc2 & BIT(i))) {
@@ -271,6 +273,10 @@ static int k3_dma_start_txd(struct k3_dma_chan *c)
if (BIT(c->phy->idx) & k3_dma_get_chan_stat(d))
return -EAGAIN;
+ /* Avoid losing track of ds_run if a transaction is in flight */
+ if (c->phy->ds_run)
+ return -EAGAIN;
+
if (vd) {
struct k3_dma_desc_sw *ds =
container_of(vd, struct k3_dma_desc_sw, vd);
--
2.7.4