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Re: [dm-devel] [PATCH v3 01/17] hashtable: introduce a small and naive hashtable



On Thu, 2012-09-06 at 07:55 -0700, Josh Triplett wrote:

> > My solution to making 'break' work in the iterator is:
> > 
> > 	for (bkt = 0, node = NULL; bkt < HASH_SIZE(name) && node == NULL; bkt++)
> > 		hlist_for_each_entry(obj, node, &name[bkt], member)
> > 
> 
> Looks reasonable.  However, it would break (or rather, not break) on
> code like this:
> 
> 	hash_for_each_entry(...) {
> 		if (...) {
> 			foo(node);
> 			node = NULL;
> 			break;
> 		}
> 	}
> 
> Hiding the double loop still seems error-prone.

We've already had this conversation ;-)  A guess a big comment is in
order:

/*
 * NOTE!  Although this is a double loop, 'break' still works because of
 *        the 'node == NULL' condition in the outer loop. On break of
 *        the inner loop, node will be !NULL, and the outer loop will
 *        exit as well.
 */

-- Steve



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