xen: improve error handling in do_suspend.

The existing error handling has a few issues:
- If freeze_processes() fails it exits with shutting_down = SHUTDOWN_SUSPEND.
- If dpm_suspend_noirq() fails it exits without resuming xenbus.
- If stop_machine() fails it exits without resuming xenbus or calling
  dpm_resume_end().
- xs_suspend()/xs_resume() and dpm_suspend_noirq()/dpm_resume_noirq() were not
  nested in the obvious way.

Fix by ensuring each failure case goto's the correct label. Treat a failure of
stop_machine() as a cancelled suspend in order to follow the correct resume
path.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>

1 files changed, 11 insertions, 9 deletions

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 7b69a1aef877..2fb7d39b814c 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -86,32 +86,32 @@ static void do_suspend(void)
         err = freeze_processes();
         if (err) {
                 printk(KERN_ERR "xen suspend: freeze failed %d\n", err);
-                return;
+                goto out;
         }
 #endif
 
         err = dpm_suspend_start(PMSG_SUSPEND);
         if (err) {
                 printk(KERN_ERR "xen suspend: dpm_suspend_start %d\n", err);
-                goto out;
+                goto out_thaw;
         }
 
-        printk(KERN_DEBUG "suspending xenstore...\n");
-        xs_suspend();
-
         err = dpm_suspend_noirq(PMSG_SUSPEND);
         if (err) {
                 printk(KERN_ERR "dpm_suspend_noirq failed: %d\n", err);
-                goto resume_devices;
+                goto out_resume;
         }
 
+        printk(KERN_DEBUG "suspending xenstore...\n");
+        xs_suspend();
+
         err = stop_machine(xen_suspend, &cancelled, cpumask_of(0));
 
         dpm_resume_noirq(PMSG_RESUME);
 
         if (err) {
                 printk(KERN_ERR "failed to start xen_suspend: %d\n", err);
-                goto out;
+                cancelled = 1;
         }
 
         if (!cancelled) {
@@ -120,15 +120,17 @@ static void do_suspend(void)
         } else
                 xs_suspend_cancel();
 
-resume_devices:
+out_resume:
         dpm_resume_end(PMSG_RESUME);
 
         /* Make sure timer events get retriggered on all CPUs */
         clock_was_set();
-out:
+
+out_thaw:
 #ifdef CONFIG_PREEMPT
         thaw_processes();
 #endif
+out:
         shutting_down = SHUTDOWN_INVALID;
 }
 #endif  /* CONFIG_PM_SLEEP */