Messages in this thread | | | Date | Sun, 24 Feb 2008 14:03:02 -0500 (EST) | From | Alan Stern <> | Subject | Re: [Bug 10030] Suspend doesn't work when SD card is inserted |
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On Sun, 24 Feb 2008, Pavel Machek wrote:
> Hi! > > > Index: usb-2.6/drivers/base/power/main.c > > =================================================================== > > --- usb-2.6.orig/drivers/base/power/main.c > > +++ usb-2.6/drivers/base/power/main.c > > @@ -25,6 +25,7 @@ > > #include <linux/pm.h> > > #include <linux/resume-trace.h> > > #include <linux/rwsem.h> > > +#include <linux/sched.h> > > > > #include "../base.h" > > #include "power.h" > > @@ -59,6 +60,13 @@ static DECLARE_RWSEM(pm_sleep_rwsem); > > > > int (*platform_enable_wakeup)(struct device *dev, int is_on); > > > > +static struct task_struct *suspending_task; > > What locking protects this variable? What happens when suspending_task > exits? (Hmm, that would probably be bug, anyway?)
It's protected by whatever existing locking scheme allows only one task to start a system sleep at a time. For example, the suspending task has to get a write lock on pm_sleep_rwsem.
Yes, if the suspending task exits before the system has woken up, you're in trouble regardless.
> Or are we running UP when this is accessed? This at least needs a big > fat comment. > > > +bool in_suspend_context(void) > > +{ > > + return (suspending_task == current); > > +}
We aren't necessarily UP. But since all that matters is whether or not suspend_task is equal to the current task, no extra locking is needed.
I'll add a comment explaining all this.
Alan Stern
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