Re: [PATCH] driver core: Fix test_async_driver_probe if NUMA is disabled

[Alexander Duyck <alexander.h.duyck@linux.intel.com>]

On Wed, 2019-11-27 at 12:24 -0800, Guenter Roeck wrote:
> Since commit 57ea974fb871 ("driver core: Rewrite test_async_driver_probe
> to cover serialization and NUMA affinity"), running the test with NUMA
> disabled results in warning messages similar to the following.
> 
> test_async_driver test_async_driver.12: NUMA node mismatch -1 != 0
> 
> If CONFIG_NUMA=n, dev_to_node(dev) returns -1, and numa_node_id()
> returns 0. Both are widely used, so it appears risky to change return
> values. Augment the check with IS_ENABLED(CONFIG_NUMA) instead
> to fix the problem.
> 
> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Fixes: 57ea974fb871 ("driver core: Rewrite test_async_driver_probe to cover serialization and NUMA affinity")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/base/test/test_async_driver_probe.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/test/test_async_driver_probe.c b/drivers/base/test/test_async_driver_probe.c
> index f4b1d8e54daf..3bb7beb127a9 100644
> --- a/drivers/base/test/test_async_driver_probe.c
> +++ b/drivers/base/test/test_async_driver_probe.c
> @@ -44,7 +44,8 @@ static int test_probe(struct platform_device *pdev)
>  	 * performing an async init on that node.
>  	 */
>  	if (dev->driver->probe_type == PROBE_PREFER_ASYNCHRONOUS) {
> -		if (dev_to_node(dev) != numa_node_id()) {
> +		if (IS_ENABLED(CONFIG_NUMA) &&
> +		    dev_to_node(dev) != numa_node_id()) {
>  			dev_warn(dev, "NUMA node mismatch %d != %d\n",
>  				 dev_to_node(dev), numa_node_id());
>  			atomic_inc(&warnings);

I'm not sure that is really the correct fix. It might be better to test it
against NUMA_NO_NODE and then if it is not that make sure that it matches
the node ID. Adding the check against NUMA_NO_NODE would resolve the issue
for cases where the device might be assigned to multiple NUMA nodes.