PCI: endpoint: Fix configfs group removal on driver teardown

commit 910bdb8 upstream.

An endpoint driver configfs attributes group is added to the
epf_group list of struct pci_epf_driver by pci_epf_add_cfs() but an
added group is not removed from this list when the attribute group is
unregistered with pci_ep_cfs_remove_epf_group().

Add the missing list_del() call in pci_ep_cfs_remove_epf_group()
to correctly remove the attribute group from the driver list.

With this change, once the loop over all attribute groups in
pci_epf_remove_cfs() completes, the driver epf_group list should be
empty. Add a WARN_ON() to make sure of that.

Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250624114544.342159-3-dlemoal@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: damien-lemoal

drivers/pci/endpoint/pci-ep-cfs.c

@@ -691,6 +691,7 @@ void pci_ep_cfs_remove_epf_group(struct config_group *group)
 	if (IS_ERR_OR_NULL(group))
 		return;
 
+	list_del(&group->group_entry);
 	configfs_unregister_default_group(group);
 }
 EXPORT_SYMBOL(pci_ep_cfs_remove_epf_group);

drivers/pci/endpoint/pci-epf-core.c

@@ -338,6 +338,7 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver)
 	mutex_lock(&pci_epf_mutex);
 	list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
 		pci_ep_cfs_remove_epf_group(group);
+	WARN_ON(!list_empty(&driver->epf_group));
 	mutex_unlock(&pci_epf_mutex);
 }