[1/4] I/OAT: fix channel resources free for not allocated channels

If the ioatdma driver is loaded but not used it does not allocate descriptors.
Before it frees channel resources it should first be sure
that they have been previously allocated.

Cc: <stable@kernel.org>
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Tested-by: Tom Picard <tom.s.picard@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index b0438c4..dbb8bbb 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -807,6 +807,12 @@
 	struct ioat_desc_sw *desc, *_desc;
 	int in_use_descs = 0;
 
+	/* Before freeing channel resources first check
+	 * if they have been previously allocated for this channel.
+	 */
+	if (ioat_chan->desccount == 0)
+		return;
+
 	tasklet_disable(&ioat_chan->cleanup_task);
 	ioat_dma_memcpy_cleanup(ioat_chan);
 
@@ -869,6 +875,7 @@
 	ioat_chan->last_completion = ioat_chan->completion_addr = 0;
 	ioat_chan->pending = 0;
 	ioat_chan->dmacount = 0;
+	ioat_chan->desccount = 0;
 	ioat_chan->watchdog_completion = 0;
 	ioat_chan->last_compl_desc_addr_hw = 0;
 	ioat_chan->watchdog_tcp_cookie =