xenfb: use the correct condition to avoid excessive looping

In commit ac0487e1 ("xenfb.c: avoid expensive loops when prod <=
out_cons"), ">=" was used. In fact, a full ring is a legit state.
Correct the test to use ">".

upstream-commit-id: 4df26e88ee2f23c01418630368e87b719ed06b75

Reported-by: "Hao, Xudong" <xudong.hao@intel.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Tested-by: "Hao, Xudong" <xudong.hao@intel.com>
Acked-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>

diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index 56d1a365117f46baf56bd7dd58201e1147a5dda6..4cde110bfa983142a2d6c9978c6b7c479843aada 100644 (file)
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -784,7 +784,7 @@ static void xenfb_handle_events(struct XenFB *xenfb)
 
     prod = page->out_prod;
     out_cons = page->out_cons;
-    if (prod - out_cons >= XENFB_OUT_RING_LEN) {
+    if (prod - out_cons > XENFB_OUT_RING_LEN) {
         return;
     }
     xen_rmb();         /* ensure we see ring contents up to prod */