[PATCH v5 3/3] PCI: endpoint: Fix find_first_zero_bit() usage

[Niklas Cassel <niklas.cassel@axis.com>]

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

Calling find_first_zero_bit() with the wrong size unit
will lead to insidious bugs.

Fix this by calling find_first_zero_bit() with size BITS_PER_LONG,
rather than sizeof() and add missing find_first_zero_bit() return
handling.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
 drivers/pci/endpoint/pci-ep-cfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index e8f65eb51c1a..c9a2fb9dd49d 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -103,7 +103,10 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 	struct pci_epf *epf = epf_group->epf;
 
 	func_no = find_first_zero_bit(&epc_group->function_num_map,
-				      sizeof(epc_group->function_num_map));
+				      BITS_PER_LONG);
+	if (func_no >= BITS_PER_LONG)
+		return -EINVAL;
+
 	set_bit(func_no, &epc_group->function_num_map);
 	epf->func_no = func_no;
 
-- 
2.14.2