Re: [2/4] consolidate bit waiting code patterns

[Andrew Morton]

William Lee Irwin III <wli@xxxxxxxxxxxxxx> wrote:
>
> +int __sched __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
>  +			void *word, int bit,
>  +			int (*wait)(void *), unsigned mode)
>  +{
>  +	int ret;
>  +
>  +	while (test_and_set_bit(bit, word)) {
>  +		prepare_to_wait_exclusive(wq, &q->wait, mode);
>  +		if (test_bit(bit, word)) {
>  +			if ((ret = (*wait)(word)))
>  +				return ret;
>  +		}
>  +	}
>  +	finish_wait(wq, &q->wait);
>  +	return 0;
>  +}

Some comments over this thing would be nice.

The `wait' argument seems to be misnamed.  It typically points at
sync_page(), yes?   Maybe it should be called `action' or `kick' or
something.

If (*wait)() returns non-zero then it looks to me like the callers will get
confused, thinking that the page did come unlocked?

If (*wait)() returns non-zero then we need to run finish_wait(), no?
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