Re: spinlock_irqsave() && flags (Was: pm80xx: Spinlock fix)

Linus Torvalds
2013-12-23T18:13:00Z

On Mon, Dec 23, 2013 at 9:27 AM, Oleg Nesterov <oleg@redhat.com> wrote:
>
> In short, is this code
>
> spinlock_t LOCK;
> unsigned long FLAGS;
>
> void my_lock(void)
> {
> spin_lock_irqsave(&LOCK, FLAGS);
> }
>
> void my_unlock(void)
> {
> spin_unlock_irqrestore(&LOCK, FLAGS);
> }
>
> correct or not?

Hell no. "flags" needs to be a thread-private variable, or at least
protected some way (ie the above could work if everything is inside a
bigger lock, to serialize access to FLAGS).

Linus