linux-kernel - [PATCH v2 2/2] PCI: endpoint: Fix find_first_zero

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Message-Id: <20171117150041.30509-3-niklas.cassel@axis.com>
Date:   Fri, 17 Nov 2017 16:00:41 +0100
From:   Niklas Cassel <niklas.cassel@...s.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Niklas Cassel <niklass@...s.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] PCI: endpoint: Fix find_first_zero_bit() usage

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 using replacing find_first_zero_bit() with ffz(),
since ffz() only works on a single 'unsigned long' and therefore
does not need a size argument.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
---
 drivers/pci/endpoint/pci-ep-cfs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index 4f74386c1ced..96b984685640 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -108,8 +108,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 	if (ret)
 		goto err_add_epf;
 
-	func_no = find_first_zero_bit(&epc_group->function_num_map,
-				      sizeof(epc_group->function_num_map));
+	func_no = ffz(epc_group->function_num_map);
 	set_bit(func_no, &epc_group->function_num_map);
 	epf->func_no = func_no;
 
-- 
2.14.2