[PATCH 090/145] dma: tegra: avoid channel lock up after free

[Kamal Mostafa]

3.8.13.5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Osipenko <digetx@xxxxxxxxx>

commit 7bdc1e272a471062e8f310137c896e2355b46d13 upstream.

Lock scenario: Channel 1 was allocated and prepared as slave_sg, used and freed.
Now preparation of cyclic dma on channel 1 will fail with err "DMA configuration
conflict" because tdc->isr_handler still setted to handle_once_dma_done.

This happens because tegra_dma_abort_all() won't be called on channel freeing
if pending list is empty and channel not busy. We need to clear isr_handler
on channel freeing to avoid locking.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Acked-by: Stephen Warren <swarren@xxxxxxxxxx>
Acked-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Cc: Jonghwan Choi <jhbird.choi@xxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 drivers/dma/tegra20-apb-dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 3cad856..b9e32fe 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1158,6 +1158,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 	list_splice_init(&tdc->free_dma_desc, &dma_desc_list);
 	INIT_LIST_HEAD(&tdc->cb_desc);
 	tdc->config_init = false;
+	tdc->isr_handler = NULL;
 	spin_unlock_irqrestore(&tdc->lock, flags);
 
 	while (!list_empty(&dma_desc_list)) {
-- 
1.8.1.2

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