[Xen-devel] [PATCH] xen: improve error handling in do_suspend.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

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@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
---
 drivers/xen/manage.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 7b69a1a..2fb7d39 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 */
-- 
1.5.6.5


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