[PATCH] powerpc/powernv: fix pci-cxl.c build when CONFIG_MODULES=n

[Andrew Donnellan]

From: Ian Munsie <imunsie at au1.ibm.com>

pnv_cxl_enable_phb_kernel_api() grabs a reference to the cxl module to
prevent it from being unloaded after the PHB has been switched to CX4 mode.
This breaks the build when CONFIG_MODULES=n as module_mutex doesn't exist.

However, if we don't have modules, we don't need to protect against the
case of the cxl module being unloaded. As such, split the relevant
code out into a function surrounded with #if IS_MODULE(CXL) so we don't try
to compile it if cxl isn't being compiled as a module.

Fixes: 5918dbc9b4ec ("powerpc/powernv: Add support for the cxl kernel api
on the real phb")
Reported-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Ian Munsie <imunsie at au1.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

Compile tested only.
---
 arch/powerpc/platforms/powernv/pci-cxl.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-cxl.c b/arch/powerpc/platforms/powernv/pci-cxl.c
index 1559ca2..40b9d19 100644
--- a/arch/powerpc/platforms/powernv/pci-cxl.c
+++ b/arch/powerpc/platforms/powernv/pci-cxl.c
@@ -166,6 +166,23 @@ int pnv_cxl_ioda_msi_setup(struct pci_dev *dev, unsigned int hwirq,
 }
 EXPORT_SYMBOL(pnv_cxl_ioda_msi_setup);
 
+#if IS_MODULE(cxl)
+static inline void get_cxl_module(void)
+{
+       struct module *cxl_module;
+
+       mutex_lock(&module_mutex);
+       cxl_module = find_module("cxl");
+       if (cxl_module)
+              __module_get(cxl_module);
+       mutex_unlock(&module_mutex);
+       if (!cxl_module)
+              return -ENODEV;
+}
+#else
+static inline void get_cxl_module(void) {}
+#endif
+
 /*
  * Sets flags and switches the controller ops to enable the cxl kernel api.
  * Original the cxl kernel API operated on a virtual PHB, but certain cards
@@ -175,7 +192,6 @@ EXPORT_SYMBOL(pnv_cxl_ioda_msi_setup);
 int pnv_cxl_enable_phb_kernel_api(struct pci_controller *hose, bool enable)
 {
 	struct pnv_phb *phb = hose->private_data;
-	struct module *cxl_module;
 
 	if (!enable) {
 		/*
@@ -194,13 +210,7 @@ int pnv_cxl_enable_phb_kernel_api(struct pci_controller *hose, bool enable)
 	 * long as we are in this mode (and since we can't safely disable this
 	 * mode once enabled...).
 	 */
-	mutex_lock(&module_mutex);
-	cxl_module = find_module("cxl");
-	if (cxl_module)
-		__module_get(cxl_module);
-	mutex_unlock(&module_mutex);
-	if (!cxl_module)
-		return -ENODEV;
+	get_cxl_module();
 
 	phb->flags |= PNV_PHB_FLAG_CXL;
 	hose->controller_ops = pnv_cxl_cx4_ioda_controller_ops;
-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited