Re: [PATCH v2 1/6] powerpc/xive: remove dead NULL check after GFP_NOFAIL allocation

As suggested by Andrew, let's change the approach and remove entirely
__GFP_NOFAIL instead and make all xive_ipis access paths NULL-safe.
   
On 7/24/26 04:28, Gou Hao wrote:
> kzalloc_objs with the __GFP_NOFAIL flag will never return NULL, so the
> subsequent NULL check is unreachable dead code. Remove it.
> 
> Signed-off-by: Gou Hao <[email protected]>
> Reviewed-by: Wentao Guan <[email protected]>
> Reviewed-by: jiazhenyuan <[email protected]>
> ---
>   arch/powerpc/sysdev/xive/common.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> index dadd1f46ec939..f2904a5c2b7bf 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -1134,9 +1134,6 @@ static int __init xive_init_ipis(void)
>   
>   	xive_ipis = kzalloc_objs(*xive_ipis, nr_node_ids,
>   				 GFP_KERNEL | __GFP_NOFAIL);

So let's remove __GFP_NOFAIL here.

> -	if (!xive_ipis)
> -		goto out_free_domain;
> -

Let's keep it now that allocation can really fail.

>   	for_each_node(node) {>   		struct xive_ipi_desc *xid = &xive_ipis[node];
>   		struct xive_ipi_alloc_info info = { node };
> @@ -1158,7 +1155,7 @@ static int __init xive_init_ipis(void)
>   
>   out_free_xive_ipis:
>   	kfree(xive_ipis);
> -out_free_domain:

and keep the out_free_domain label

> +	xive_ipis = NULL;

and yes we should add 'xive_ipis = NULL;'

>   	irq_domain_remove(ipi_domain);
>   out_free_fwnode:
>   	irq_domain_free_fwnode(fwnode);


The prepare_cpu() path is broken. To fix, we need to check xive_ipis
is not NULL in xive_setup_cpu_ipi() and xive_cleanup_cpu_ipi(). It
should be a straight forward local change. Nothing complex.

You can test with QEMU. The pSeries and the PowerNV machines are well
supported under emulation. Ping me if you need help.

Thanks,

C.