[PATCH 5.16 100/126] gve: fix the wrong AdminQ buffer queue index check

Greg Kroah-Hartman
2022-02-07T12:00:13Z

From: Haiyue Wang <haiyue.wang@intel.com>

commit 1f84a9450d75e08af70d9e2f2d5e1c0ac0c881d2 upstream.

The 'tail' and 'head' are 'unsigned int' type free-running count, when
'head' is overflow, the 'int i (= tail) < u32 head' will be false:

Only '- loop 0: idx = 63' result is shown, so it needs to use 'int' type
to compare, it can handle the overflow correctly.

typedef uint32_t u32;

int main()
{
u32 tail, head;
int stail, shead;
int i, loop;

tail = 0xffffffff;
head = 0x00000000;

for (i = tail, loop = 0; i < head; i++) {
unsigned int idx = i & 63;

printf("+ loop %d: idx = %u\n", loop++, idx);
}

stail = tail;
shead = head;
for (i = stail, loop = 0; i < shead; i++) {
unsigned int idx = i & 63;

printf("- loop %d: idx = %u\n", loop++, idx);
}

return 0;
}

Fixes: 5cdad90de62c ("gve: Batch AQ commands for creating and destroying queues.")
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/google/gve/gve_adminq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -301,7 +301,7 @@ static int gve_adminq_parse_err(struct g
*/
static int gve_adminq_kick_and_wait(struct gve_priv *priv)
{
- u32 tail, head;
+ int tail, head;
int i;

tail = ioread32be(&priv->reg_bar0->adminq_event_counter);