xen/fb: fix potential memory leak

This patch fixes a potential memory leak when xenfb connect to
the backend fails.

Thanks for Ian's review and comments.

[v2: reworded the commit message a bit]

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>
Tested-by: Gurudas Pai <gurudas.pai@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index f92313d33e27..95bbd0a1e5da 100644
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -562,26 +562,24 @@ static void xenfb_init_shared_page(struct xenfb_info *info,
 static int xenfb_connect_backend(struct xenbus_device *dev,
                                  struct xenfb_info *info)
 {
-        int ret, evtchn;
+        int ret, evtchn, irq;
         struct xenbus_transaction xbt;
 
         ret = xenbus_alloc_evtchn(dev, &evtchn);
         if (ret)
                 return ret;
-        ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
+        irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
                                         0, dev->devicetype, info);
-        if (ret < 0) {
+        if (irq < 0) {
                 xenbus_free_evtchn(dev, evtchn);
                 xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
-                return ret;
+                return irq;
         }
-        info->irq = ret;
-
  again:
         ret = xenbus_transaction_start(&xbt);
         if (ret) {
                 xenbus_dev_fatal(dev, ret, "starting transaction");
-                return ret;
+                goto unbind_irq;
         }
         ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
                             virt_to_mfn(info->page));
@@ -603,15 +601,18 @@ static int xenfb_connect_backend(struct xenbus_device *dev,
                 if (ret == -EAGAIN)
                         goto again;
                 xenbus_dev_fatal(dev, ret, "completing transaction");
-                return ret;
+                goto unbind_irq;
         }
 
         xenbus_switch_state(dev, XenbusStateInitialised);
+        info->irq = irq;
         return 0;
 
  error_xenbus:
         xenbus_transaction_end(xbt, 1);
         xenbus_dev_fatal(dev, ret, "writing xenstore");
+ unbind_irq:
+        unbind_from_irqhandler(irq, info);
         return ret;
 }