* Grant Likely wrote:

Hi Thierry,

On Fri, Jan 6, 2012 at 7:28 AM, Thierry Reding
[off-list ref] wrote:

quoted

The irq_domain_add() function needs the number of interrupts in the
domain to properly initialize them. In addition the allocated domain
is now returned by the irq_domain_{add,generate}_simple() helpers.

The commit text should also include the justification for renaming
irq_domain_create_simple() -> irq_domain_add_simple()

Actually the commit only fixes up the comment. The function has always been
called irq_domain_add_simple().

For reference, this was introduced in commit 7e71330.

quoted

       domain = kzalloc(sizeof(*domain), GFP_KERNEL);
-       if (!domain) {
-               WARN_ON(1);
-               return;
-       }
+       if (!domain)
+               return ERR_PTR(-ENOMEM);

Don't use the ERR_PTR() pattern (it's a horrible pattern IMHO).

Returning NULL here is probably okay. Can the ERR_PTR stay in
irq_domain_generate_simple(), though? It has two error conditions and
handling both by returning NULL may not be what we want.

Return NULL on failure and keep the WARN_ON() in this function.
Otherwise looks good.  Thanks for writing this patch.

I thought it would be better to pull the WARN_ON out of the function because
we now actually have a way to determine if the call succeeded in the caller.
In most cases I assume the caller will be much better suited to handle the
situation gracefully such that the WARN_ON is not required.

Thierry