From: John Stultz <john.stultz@xxxxxxxxxx> [ Upstream commit 2f42e05b942fe2fbfb9bbc6e34e1dd8c3ce4f3a4 ] 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@xxxxxxxxxx> [add ss tag] Link: https://lore.kernel.org/r/20191218190906.6641-1-john.stultz@xxxxxxxxxx Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/dma/k3dma.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/dma/k3dma.c b/drivers/dma/k3dma.c index 6bfa217ed6d0..ba3c3791f9dc 100644 --- a/drivers/dma/k3dma.c +++ b/drivers/dma/k3dma.c @@ -222,9 +222,11 @@ 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))) { @@ -264,6 +266,10 @@ 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); -- 2.20.1
