If your task doesn't sleep it won't be pre-empted. However on an SMP box
they might run in parallel one day.
You can either use spinlocks or semaphores. spinlocks can only be held for
short durations (ideally anyway) but have very very low overhead. A semaphore
can be held without impacting overall system efficiency.
In your case I'd probably use a spin lock like so
spinlock_t ioaccess_lock;
get_user(...)
spin_lock(&ioaccess_lock);
outb(foo)
outb(bar)
spin_unlock(&ioaccess_lock);
init:
spin_lock_init(&io_access_lock);
See the 2.3.x radio drivers for some fairly simple examples
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/