RE: [PATCH 2/2] futex, x86/mce: Avoid double machine checks
From: Luck, Tony
Date: Fri Jan 08 2021 - 18:11:20 EST
> I think this is horrid; why can't we have it return something different
> then -EFAULT instead?
I did consider this ... but it appears that architectures aren't unified in the
return value from get_user()
Here's another function involved in the futex call chain leading to this:
static int get_futex_value_locked(u32 *dest, u32 __user *from)
{
int ret;
pagefault_disable();
ret = __get_user(*dest, from);
pagefault_enable();
return ret ? -EFAULT : 0;
}
It seems like the expectation here is just "zero or not" and we
don't care what the "not" value is ... just turn it into -EFAULT.
-Tony