ehci-dbgp: avoid division by zero.

Unlikely to ever see hardware reporting 0 ports, but might as well
fail gracefully if we do.

Coverity CID 1055266

Signed-off-by: Tim Deegan <tim@xen.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/drivers/char/ehci-dbgp.c b/xen/drivers/char/ehci-dbgp.c
index 301eedf22ee2a91d163df6ab08f5066c3141cdc5..b900d6092edbed39ca11a212601e2a9f9bb11488 100644 (file)
--- a/xen/drivers/char/ehci-dbgp.c
+++ b/xen/drivers/char/ehci-dbgp.c
@@ -1094,6 +1094,9 @@ try_next_port:
     dbgp_printk("n_ports:    %u\n", n_ports);
     ehci_dbgp_status(dbgp, "");
 
+    if ( n_ports == 0 )
+        return -1;
+
     for ( i = 1; i <= n_ports; i++ )
     {
         portsc = readl(&dbgp->ehci_regs->port_status[i-1]);