[PATCH v2] qed/qed_dev: guard against a possible division by zero

[Daniil Tatianin]

Previously we would divide total_left_rate by zero if num_vports
happened to be 1 because non_requested_count is calculated as
num_vports - req_count. Guard against this by validating num_vports at
the beginning and returning an error otherwise.

Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.

Fixes: bcd197c81f63 ("qed: Add vport WFQ configuration APIs")
Signed-off-by: Daniil Tatianin <d-tatianin@xxxxxxxxxxxxxx>
Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
---
Changes since v1:
- Don't break DP_NOTICE into multiple lines
- Add a reviewed-by tag
---
 drivers/net/ethernet/qlogic/qed/qed_dev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_dev.c b/drivers/net/ethernet/qlogic/qed/qed_dev.c
index d61cd32ec3b6..86a93cac2647 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_dev.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_dev.c
@@ -5083,6 +5083,11 @@ static int qed_init_wfq_param(struct qed_hwfn *p_hwfn,
 
 	num_vports = p_hwfn->qm_info.num_vports;
 
+	if (num_vports < 2) {
+		DP_NOTICE(p_hwfn, "Unexpected num_vports: %d\n", num_vports);
+		return -EINVAL;
+	}
+
 	/* Accounting for the vports which are configured for WFQ explicitly */
 	for (i = 0; i < num_vports; i++) {
 		u32 tmp_speed;
-- 
2.25.1