PCI: endpoint: Clear secondary (not primary) EPC in pci_epc_remove_epf()

In addition to a primary endpoint controller, an endpoint function may be
associated with a secondary endpoint controller, epf->sec_epc, to provide
NTB (non-transparent bridge) functionality.

Previously, pci_epc_remove_epf() incorrectly cleared epf->epc instead of
epf->sec_epc when removing from the secondary endpoint controller.

Extend the epc->list_lock coverage and clear either epf->epc or
epf->sec_epc as indicated.

Link: https://lore.kernel.org/r/20241107-epc_rfc-v2-2-da5b6a99a66f@quicinc.com
Fixes: 63840ff53223 ("PCI: endpoint: Add support to associate secondary EPC with EPF")
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[mani: reworded subject and description]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 21af2db..bed7c7d 100644 (file)
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -746,18 +746,18 @@ void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
        if (IS_ERR_OR_NULL(epc) || !epf)
                return;
 
+       mutex_lock(&epc->list_lock);
        if (type == PRIMARY_INTERFACE) {
                func_no = epf->func_no;
                list = &epf->list;
+               epf->epc = NULL;
        } else {
                func_no = epf->sec_epc_func_no;
                list = &epf->sec_epc_list;
+               epf->sec_epc = NULL;
        }
-
-       mutex_lock(&epc->list_lock);
        clear_bit(func_no, &epc->function_num_map);
        list_del(list);
-       epf->epc = NULL;
        mutex_unlock(&epc->list_lock);
 }
 EXPORT_SYMBOL_GPL(pci_epc_remove_epf);