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

[Linus Torvalds]

On Mon, Dec 23, 2013 at 9:27 AM, Oleg Nesterov <oleg@xxxxxxxxxx> 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
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