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

[Maciej Sosnowski <maciej.sosnowski@intel.com>]

From: Maciej Sosnowski <maciej.sosnowski@intel.com>

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>
---

 drivers/dma/ioat_dma.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index b0438c4..687eef7 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -807,6 +807,12 @@ static void ioat_dma_free_chan_resources
 	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 @@ static void ioat_dma_free_chan_resources
 	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 =