[dpdk-stable] [PATCH 18.11] net/netvsc: fix chimney index

[Long Li]

From: Long Li <longli at microsoft.com>

[ upstream commit 3eee636809e449b8b4c0cdfaf841f2d0e4a558e8 ]

The code should look into "slab" to figure out the index returned from
rte_bitmap_scan().

Fixes: cc02518132 ("net/netvsc: split send buffers from Tx descriptors")

Signed-off-by: Long Li <longli at microsoft.com>
Acked-by: Stephen Hemminger <stephen at networkplumber.org>
---
 drivers/net/netvsc/hn_rxtx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netvsc/hn_rxtx.c b/drivers/net/netvsc/hn_rxtx.c
index cdd44a76c3..535f27d009 100644
--- a/drivers/net/netvsc/hn_rxtx.c
+++ b/drivers/net/netvsc/hn_rxtx.c
@@ -206,11 +206,13 @@ hn_chim_uninit(struct rte_eth_dev *dev)
 static uint32_t hn_chim_alloc(struct hn_data *hv)
 {
 	uint32_t index = NVS_CHIM_IDX_INVALID;
-	uint64_t slab;
+	uint64_t slab = 0;
 
 	rte_spinlock_lock(&hv->chim_lock);
-	if (rte_bitmap_scan(hv->chim_bmap, &index, &slab))
+	if (rte_bitmap_scan(hv->chim_bmap, &index, &slab)) {
+		index += __builtin_ctzll(slab);
 		rte_bitmap_clear(hv->chim_bmap, index);
+	}
 	rte_spinlock_unlock(&hv->chim_lock);
 
 	return index;
-- 
2.25.1