Re: [patch] irqlock patch -G3. [was Re: odd memory corruption

[Ingo Molnar]

On Tue, 23 Jul 2002, Andrew Morton wrote:

> Robert and George's patch doesn't seem to be optimal though - if we're
> not going to preempt at spin_unlock() time, we need to preempt at
> local_irq_restore() time.  It'll be untrivial to fix all this, but this
> very subtle change to the locking semantics with CONFIG_PREEMPT is quite
> nasty.

this is precisely the reason why we cannot pretend these bugs do not exist
and just work this around in preempt_schedule(). Code that relies on
cli/sti for atomicity should be pretty rare and limited, there's 1 known
case so far where it leads to bugs.

	Ingo