dmaengine: mv_xor_v2: properly handle wrapping in the array of HW descriptors

mv_xor_v2_tasklet() is looping over completed HW descriptors. Before the
loop, it initializes 'next_pending_hw_desc' to the first HW descriptor
to handle, and then the loop simply increments this point, without
taking care of wrapping when we reach the last HW descriptor. The
'pending_ptr' index was being wrapped back to 0 at the end, but it
wasn't used in each iteration of the loop to calculate
next_pending_hw_desc.

This commit fixes that, and makes next_pending_hw_desc a variable local
to the loop itself.

Fixes: 19a340b1a820 ("dmaengine: mv_xor_v2: new driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/mv_xor_v2.c b/drivers/dma/mv_xor_v2.c
index e928020..bdfb36e 100644 (file)
--- a/drivers/dma/mv_xor_v2.c
+++ b/drivers/dma/mv_xor_v2.c
@@ -560,7 +560,6 @@ static void mv_xor_v2_tasklet(unsigned long data)
 {
        struct mv_xor_v2_device *xor_dev = (struct mv_xor_v2_device *) data;
        int pending_ptr, num_of_pending, i;
-       struct mv_xor_v2_descriptor *next_pending_hw_desc = NULL;
        struct mv_xor_v2_sw_desc *next_pending_sw_desc = NULL;
 
        dev_dbg(xor_dev->dmadev.dev, "%s %d\n", __func__, __LINE__);
@@ -568,17 +567,10 @@ static void mv_xor_v2_tasklet(unsigned long data)
        /* get the pending descriptors parameters */
        num_of_pending = mv_xor_v2_get_pending_params(xor_dev, &pending_ptr);
 
-       /* next HW descriptor */
-       next_pending_hw_desc = xor_dev->hw_desq_virt + pending_ptr;
-
        /* loop over free descriptors */
        for (i = 0; i < num_of_pending; i++) {
-
-               if (pending_ptr > MV_XOR_V2_DESC_NUM)
-                       pending_ptr = 0;
-
-               if (next_pending_sw_desc != NULL)
-                       next_pending_hw_desc++;
+               struct mv_xor_v2_descriptor *next_pending_hw_desc =
+                       xor_dev->hw_desq_virt + pending_ptr;
 
                /* get the SW descriptor related to the HW descriptor */
                next_pending_sw_desc =
@@ -614,6 +606,8 @@ static void mv_xor_v2_tasklet(unsigned long data)
 
                /* increment the next descriptor */
                pending_ptr++;
+               if (pending_ptr >= MV_XOR_V2_DESC_NUM)
+                       pending_ptr = 0;
        }
 
        if (num_of_pending != 0) {