Re: [PATCH 11/17] fuse: add number of waiting requests attribute

[Andrew Morton <akpm@osdl.org>]

Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> +	/** The number of requests waiting for completion */
> +	atomic_t num_waiting;

This doesn't get initialised anywhere.

Presumably you're relying on a memset somewhere.  That might work on all
architectures, AFAIK.  But in theory it's wrong.  If, for example, the
architecture implements atomic_t via a spinlock-plus-integer, and that
spinlock's unlocked state is not all-bits-zero, we're dead.

So we should initialise it with

	foo->num_waiting = ATOMIC_INIT(0);



nb: it is not correct to initialise an atomic_t with

	atomic_set(a, 0);

because in the above theoretical case case where the arch uses a spinlock
in the atomic_t, that spinlock doesn't get initialised.  I bet we've got code
in there which does this.