swsusp doesn't suspend devices

Pierre Ossman
2005-09-07T11:20:00Z

It would seem that swsusp doesn't properly suspend devices, or more
precisely it wakes them up again before suspending the machine.

The problem is in swsusp_suspend(). It is designed as if
swsusp_arch_suspend() would suspend the hardware, when in fact all it
does is prepare for a suspend. The effect is that devices are brought
back up because swsusp_suspend() believes it is resuming.

Below is a patch that uses the same system as kernel/power/disk.c to
determine if it's suspending or resuming. The patch brings up a new
problem though, disk writes generate a huge amount of "scheduling while
atomic".

---

Index: linux-wbsd/kernel/power/swsusp.c
===================================================================
--- linux-wbsd/kernel/power/swsusp.c (revision 165)
+++ linux-wbsd/kernel/power/swsusp.c (working copy)
@@ -84,6 +84,8 @@
/* Local variables that should not be affected by save */
static unsigned int nr_copy_pages __nosavedata = 0;

+static int in_suspend __nosavedata = 0;
+
/* Suspend pagedir is allocated before final copy, therefore it
must be freed after resume

@@ -897,15 +899,18 @@
return error;
}

+ in_suspend = 1;
save_processor_state();
if ((error = swsusp_arch_suspend()))
printk("Error %d suspending\n", error);
- /* Restore control flow magically appears here */
- restore_processor_state();
- BUG_ON (nr_copy_pages_check != nr_copy_pages);
- restore_highmem();
- device_power_up();
- local_irq_enable();
+ if (!in_suspend || error) {
+ /* Restore control flow magically appears here */
+ restore_processor_state();
+ BUG_ON (nr_copy_pages_check != nr_copy_pages);
+ restore_highmem();
+ device_power_up();
+ local_irq_enable();
+ }
return error;
}