[PATCH] ioatdma: silence GCC warnings

[Paul Bolle <pebolle@tiscali.nl>]

Building dma_v3.o triggers two GCC warnings:
    drivers/dma/ioat/dma_v3.c: In function ‘__ioat3_prep_pq16_lock’:
    drivers/dma/ioat/dma_v3.c:264:11: warning: array subscript is below array bounds [-Warray-bounds]
    drivers/dma/ioat/dma_v3.c:264:11: warning: array subscript is below array bounds [-Warray-bounds]

These warnings are caused by pq16_set_src(). It uses "int idx" as an
index to an eight element array. Changing "idx" to unsigned int silences
these warnings. Apparently GCC can then determine that "idx" will never
be negative.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
---
0) Compile tested only.

1) These warning were introduced in v3.10-rc1. That must have been
through commit 7727eaa449 ("ioatdma: Adding support for 16 src PQ ops
and super extended descriptors").

 drivers/dma/ioat/dma_v3.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c
index ca6ea9b..b5102da 100644
--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -251,7 +251,7 @@ static bool is_bwd_noraid(struct pci_dev *pdev)
 }
 
 static void pq16_set_src(struct ioat_raw_descriptor *desc[3],
-			dma_addr_t addr, u32 offset, u8 coef, int idx)
+			dma_addr_t addr, u32 offset, u8 coef, unsigned int idx)
 {
 	struct ioat_pq_descriptor *pq = (struct ioat_pq_descriptor *)desc[0];
 	struct ioat_pq16a_descriptor *pq16 =
@@ -1180,7 +1180,7 @@ __ioat3_prep_pq16_lock(struct dma_chan *c, enum sum_check_flags *result,
 	struct ioat_pq_descriptor *pq;
 	u32 offset = 0;
 	u8 op;
-	int i, s, idx, num_descs;
+	int i, idx, num_descs;
 
 	/* this function only handles src_cnt 9 - 16 */
 	BUG_ON(src_cnt < 9);
@@ -1206,6 +1206,7 @@ __ioat3_prep_pq16_lock(struct dma_chan *c, enum sum_check_flags *result,
 	do {
 		struct ioat_raw_descriptor *descs[4];
 		size_t xfer_size = min_t(size_t, len, 1 << ioat->xfercap_log);
+		unsigned int s;
 
 		desc = ioat2_get_ring_ent(ioat, idx + i);
 		pq = desc->pq;
-- 
1.8.1.4