Re: BUG or not? GFP_KERNEL with interrupts disabled.

On Thu, 27 Mar 2003, Dan Eble wrote:

This makes checks like the following (in alloc_skb) asymmetric:

    if (in_interrupt() && (gfp_mask & __GFP_WAIT)) {
        static int count = 0;
        if (++count < 5) {
            printk(KERN_ERR "alloc_skb called nonatomically "
                   "from interrupt %p\n", NET_CALLER(size));
            BUG();

In a driver I'm writing, this bug was hidden until I switched from using
write_lock_irqsave() to write_lock_bh().  Shouldn't this bug also be
announced if interrupts are disabled?

Yeah. It should also probably use "in_atomic()" instead of 
"in_interrupt()", since that also finds people who have marked themselves 
non-preemptible.

So what the test SHOULD look like is this:

	if (gfp_mask & __GFP_WAIT) {
		if (in_atomic() || irqs_disabled()) {
			static int count = 0;
			...
		}
	}

which should catch all the cases we really care about.

		Linus