Re: PI mutex support on ARM

From: Remy Bohmer
Date: Sun Jul 08 2007 - 16:17:52 EST


Hello Ingo,

patch format problem: never diff the asm/ files, diff the asm-arm/ files.
Yeah, of course, I know, I believe I made a real mess of this one ...

is it safe to do a get_user() with irqs off?
rhetorical question ;-))
I was wondering, Is it safe to use a normal spinlock here, like this?

------- 8-< -------------
spin_lock(&futex_lock);

err = get_user(uval, uaddr);
if ((!err) && (uval == oldval))
err = put_user(newval, uaddr);

spin_unlock(&futex_lock);
------- 8-< -------------

is this method of atomic ops SMP-safe?
another rhetorical question ;-))
Nope, I already knew that, that why I mentioned that it probably only
worked on UP...

Remy
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