[PATCH 1/7] dmaengine: ep93xx: drain tasklet before freeing channel resources

[Jiale Yao]

The DMA interrupt handler can schedule the channel tasklet. Releasing
the IRQ waits for a running interrupt handler, but it does not drain a
tasklet that was already queued.

The channel resource release path frees the software descriptors and
disables the clock while such a tasklet can still access the channel and
invoke a completion callback.

Free the IRQ first to stop new tasklet producers, then kill the tasklet
before releasing the descriptors and clock.

Fixes: 5fa29a17fabf ("dmaengine: add ep93xx DMA support")
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 drivers/dma/ep93xx_dma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/ep93xx_dma.c b/drivers/dma/ep93xx_dma.c
index 311e55a97ba9..6134e9ca699d 100644
--- a/drivers/dma/ep93xx_dma.c
+++ b/drivers/dma/ep93xx_dma.c
@@ -1015,11 +1015,13 @@ static void ep93xx_dma_free_chan_resources(struct dma_chan *chan)
 	list_splice_init(&edmac->free_list, &list);
 	spin_unlock_irqrestore(&edmac->lock, flags);
 
+	free_irq(edmac->irq, edmac);
+	tasklet_kill(&edmac->tasklet);
+
 	list_for_each_entry_safe(desc, d, &list, node)
 		kfree(desc);
 
 	clk_disable_unprepare(edmac->clk);
-	free_irq(edmac->irq, edmac);
 }
 
 /**
-- 
2.34.1