PCI: endpoint: pci-epf-test: Make use of cached 'epc_features' in pci_epf_test_core_init()

Instead of getting the epc_features from pci_epc_get_features() API, use
the cached pci_epf_test::epc_features value to avoid the NULL check. Since
the NULL check is already performed in pci_epf_test_bind(), having one more
check in pci_epf_test_core_init() is redundant and it is not possible to
hit the NULL pointer dereference.

Also with commit a01e7214 ("PCI: endpoint: Remove "core_init_notifier"
flag"), 'epc_features' got dereferenced without the NULL check, leading to
the following false positive Smatch warning:

  drivers/pci/endpoint/functions/pci-epf-test.c:784 pci_epf_test_core_init() error: we previously assumed 'epc_features' could be null (see line 747)

Thus, remove the redundant NULL check and also use the epc_features::
{msix_capable/msi_capable} flags directly to avoid local variables.

[kwilczynski: commit log]
Fixes: 5e50ee27 ("PCI: pci-epf-test: Add support to defer core initialization")
Closes: https://lore.kernel.org/linux-pci/024b5826-7180-4076-ae08-57d2584cca3f@moroto.mountain
Link: https://lore.kernel.org/linux-pci/20240418-pci-epf-test-fix-v2-1-eacd54831444@linaro.orgReported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>

drivers/pci/endpoint/functions/pci-epf-test.c

@@ -735,20 +735,12 @@ static int pci_epf_test_core_init(struct pci_epf *epf)
 {
 	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
 	struct pci_epf_header *header = epf->header;
-	const struct pci_epc_features *epc_features;
+	const struct pci_epc_features *epc_features = epf_test->epc_features;
 	struct pci_epc *epc = epf->epc;
 	struct device *dev = &epf->dev;
 	bool linkup_notifier = false;
-	bool msix_capable = false;
-	bool msi_capable = true;
 	int ret;
 
-	epc_features = pci_epc_get_features(epc, epf->func_no, epf->vfunc_no);
-	if (epc_features) {
-		msix_capable = epc_features->msix_capable;
-		msi_capable = epc_features->msi_capable;
-	}
-
 	if (epf->vfunc_no <= 1) {
 		ret = pci_epc_write_header(epc, epf->func_no, epf->vfunc_no, header);
 		if (ret) {
@@ -761,7 +753,7 @@ static int pci_epf_test_core_init(struct pci_epf *epf)
 	if (ret)
 		return ret;
 
-	if (msi_capable) {
+	if (epc_features->msi_capable) {
 		ret = pci_epc_set_msi(epc, epf->func_no, epf->vfunc_no,
 				      epf->msi_interrupts);
 		if (ret) {
@@ -770,7 +762,7 @@ static int pci_epf_test_core_init(struct pci_epf *epf)
 		}
 	}
 
-	if (msix_capable) {
+	if (epc_features->msix_capable) {
 		ret = pci_epc_set_msix(epc, epf->func_no, epf->vfunc_no,
 				       epf->msix_interrupts,
 				       epf_test->test_reg_bar,