On Mon, 7 Mar 2016 11:41:37 -0500 (EST)
Alan Stern <st...@rowland.harvard.edu> wrote:
> It's hard to call this a compiler bug, but perhaps it is -- I don't
> know how programmers are supposed to tell CLANG that a subroutine
> modifies the Interrupt Flag in a way that the compiler shouldn't mess
> up.
Really! This is what's is happening??
Clang takes this:
if (!--hid->open) {
spin_unlock_irq(X);
do_something();
} else {
spin_unlock_irq(X);
}
Thus it's basically doing:
FLAG = !--hid->open;
push flags;
spin_unlock_irq(X)
pop flags;
if (FLAG zero set) {
do_something();
}
OUCH!!! There's gotta be a way to turn that off, otherwise Clang can
not be used to compile the kernel.
Nice detective work.
-- Steve
