gve: fix the wrong AdminQ buffer queue index check

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>

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 2ad7f57f7e5b52780493d647d384684a65169df0..f7621ab672b9bce6ecca27b9b6b4a18f3d547bc7 100644 (file)
--- 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 gve_priv *priv, u32 status)
  */
 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);