PCI: dwc: Deallocate EPC memory on dw_pcie_ep_init() errors

If dw_pcie_ep_init() fails to perform any action after the EPC memory is
initialized and the MSI memory region is allocated, the latter parts won't
be undone thus causing a memory leak.  Add a cleanup-on-error path to fix
these leaks.

[bhelgaas: commit log]
Fixes: 2fd0c9d9 ("PCI: designware-ep: Pre-allocate memory for MSI in dw_pcie_ep_init")
Link: https://lore.kernel.org/r/20220624143428.8334-6-Sergey.Semin@baikalelectronics.ruTested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

drivers/pci/controller/dwc/pcie-designware-ep.c

@@ -780,8 +780,9 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 	ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys,
 					     epc->mem->window.page_size);
 	if (!ep->msi_mem) {
+		ret = -ENOMEM;
 		dev_err(dev, "Failed to reserve memory for MSI/MSI-X\n");
-		return -ENOMEM;
+		goto err_exit_epc_mem;
 	}
 
 	if (ep->ops->get_features) {
@@ -790,6 +791,19 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 			return 0;
 	}
 
-	return dw_pcie_ep_init_complete(ep);
+	ret = dw_pcie_ep_init_complete(ep);
+	if (ret)
+		goto err_free_epc_mem;
+
+	return 0;
+
+err_free_epc_mem:
+	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
+			      epc->mem->window.page_size);
+
+err_exit_epc_mem:
+	pci_epc_mem_exit(epc);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_ep_init);