Francois Romieu <[email protected]> wrote:
>
> + unsigned int watchdog_fired : 1;
> unsigned int default_port : 4; /* Last dev->if_port value. */
> unsigned int have_thread : 1;
Bear in mind that the compiler will put these three fields into the same
word and will use non-atomic RMWs when they are modified.
In this particualr case it's hard to see how an SMP or IRQ race can occur,
but it's a trap. Which won't show up on x86.
struct x {
unsigned int a:1;
unsigned int b:1;
};
void foo(struct x *a)
{
a->a = 1;
}
void bar(struct x *a)
{
a->b = 1;
}
On ppc:
foo:
lwz 0,0(3)
oris 0,0,0x8000
stw 0,0(3)
blr
.size foo, .-foo
.align 2
.globl bar
.type bar, @function
bar:
lwz 0,0(3)
oris 0,0,0x4000
stw 0,0(3)
blr
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