Patch "dmaengine: ti-dma-crossbar: Fix possible race condition with dma_inuse" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

dmaengine: ti-dma-crossbar: Fix possible race condition with dma_inuse

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dmaengine-ti-dma-crossbar-fix-possible-race-condition-with-dma_inuse.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Ujfalusi <[email protected]>
Date: Thu, 21 Sep 2017 14:35:32 +0300
Subject: dmaengine: ti-dma-crossbar: Fix possible race condition with dma_inuse

From: Peter Ujfalusi <[email protected]>

commit 2ccb4837c938357233a0b8818e3ca3e58242c952 upstream.

When looking for unused xbar_out lane we should also protect the set_bit() call with the same mutex to protect against concurrent threads picking the same ID.

---
 drivers/dma/ti-dma-crossbar.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -262,13 +262,14 @@ static void *ti_dra7_xbar_route_allocate
 	mutex_lock(&xbar->mutex);
 	map->xbar_out = find_first_zero_bit(xbar->dma_inuse,
 					    xbar->dma_requests);
-	mutex_unlock(&xbar->mutex);
 	if (map->xbar_out == xbar->dma_requests) {
+		mutex_unlock(&xbar->mutex);
 		dev_err(&pdev->dev, "Run out of free DMA requests\n");
 		kfree(map);
 		return ERR_PTR(-ENOMEM);
 	}
 	set_bit(map->xbar_out, xbar->dma_inuse);
+	mutex_unlock(&xbar->mutex);
 
 	map->xbar_in = (u16)dma_spec->args[0];
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/dmaengine-edma-align-the-memcpy-acnt-array-size-with-the-transfer.patch queue-4.9/dmaengine-ti-dma-crossbar-fix-possible-race-condition-with-dma_inuse.patch