Re: possible race condition for usb_stor_port_reset and usb_reset_and_verify_device

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On Wed, 27 May 2015, yoma sophian wrote:

> After reading the kernel power document, freezing-of-tasks.txt , can I
> get the below conclusion:
> if I put my thread in freezable, it will get frozen automatically
> whenever the system goes in to suspend or hibernate.

It's not entirely automatic.  Your thread has to call try_to_freeze() 
at appropriate spots.  Of course, if your thread is a work queue then 
the workqueue core will do that for you.

> And automatically be waked up when all other thread finish their job?

No, when the system wakes up.

> in my case, since I didn't put my own sd_check_events thread into
> freezable case.
> once the system resume, it will cause the race condition as I
> mentioned previously, right?

Yes.

> if my conclusion is correct, would you mind to let me know where the
> kernel sequencially wake up normal then freezable threads?

Threads get frozen and woken up in kernel/power/process.c.  The 
routines are called from suspend_freeze_processes() and 
suspend_thaw_processes() in kernel/power/suspend.c.

Alan Stern

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