Subject: Re: Kernel crash after using new Intel NIC (igb)

From: Arun Sharma <[email-masked]>
Date: Fri, 27 May 2011 10:52:22 -0700

On 5/26/11 8:27 PM, Eric Dumazet wrote:

Looks good. Thanks for taking care of this.

> +static bool atomic_add_unless_return(atomic_t *ptr, int a, int u, int *newv)
> +{
> +	int cur, old = atomic_read(ptr);
> +
> +	while (old != u) {
> +		*newv = old + a;
> +		cur = atomic_cmpxchg(ptr, old, *newv);
> +		if (cur == old)
> +			return true;
> +		old = cur;
> +	}
> +	return false;
> +}

This looks very similar to atomic_add_unless(). If we had a

__atomic_add_unless() that returned "old", we could then do:

atomic_add_unless() { return __atomic_add_unless() != u }
atomic_add_unless_return() { return __atomic_add_unless() + a}

  -Arun