[PATCH] cxl/acpi: fix CXL_ACPI=y + CXL_PMEM=m link failure

[Gregory Price <gourry@gourry.net>]

Commit e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to
cxl_pmem.ko") moved devm_cxl_add_nvdimm_bridge() from cxl_core into
cxl_pmem, creating a symbol dependency from cxl_acpi to cxl_pmem.

When CXL_ACPI=y and CXL_PMEM=m, the built-in cxl_acpi attempts to
link against a non-built-in cxl_pmem, which the linker cannot resolve.

CXL_PMEM depends on LIBNVDIMM, so LIBNVDIMM=m constrains CXL_PMEM to
at most =m.

Change IS_ENABLED() to IS_REACHABLE(), which returns false when a
built-in caller references a modular target, preventing the link error.

The result is if the pmem/nvdimm symbols are not reachable at build
time, then at runtime it will always return -ENODEV.

Fixes: e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko")
Signed-off-by: Gregory Price <gourry@gourry.net>
---
 drivers/cxl/acpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 127537628817..7065413eda9f 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -952,7 +952,7 @@ static int cxl_acpi_probe(struct platform_device *pdev)
 	if (rc < 0)
 		return rc;
 
-	if (IS_ENABLED(CONFIG_CXL_PMEM))
+	if (IS_REACHABLE(CONFIG_CXL_PMEM))
 		rc = device_for_each_child(&root_port->dev, root_port,
 					   add_root_nvdimm_bridge);
 	if (rc < 0)
-- 
2.53.0