Thread (5 messages) flat view 5 messages, 2 authors, 2016-08-23
STALE3672d

[PATCH] serial: vt8500_serial: Fix a parameter of find_first_zero_bit.

From: Christophe JAILLET <hidden>
Date: 2016-08-21 21:29:09
Also in: kernel-janitors, linux-serial, lkml
Subsystem: arm/vt8500 arm architecture, the rest, tty layer and serial drivers · Maintainers: Alexey Charkov, Krzysztof Kozlowski, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby

The 2nd parameter of 'find_first_zero_bit' is the number of bits to search.
In this case, we are passing 'sizeof(vt8500_ports_in_use)'.
'vt8500_ports_in_use' is an 'unsigned long'. So the sizeof is likely to
return 4.

A few lines below, we check if it is below VT8500_MAX_PORTS, which is 6.

It is likely that the number of bits in a long was expected here, so use
BITS_PER_LONG instead.


It has been spotted by the following coccinelle script:
@@
expression ret, x;

@@
*  ret = \(find_first_bit \| find_first_zero_bit\) (x, sizeof(...));

Signed-off-by: Christophe JAILLET <redacted>
---
Other options are possible:
  - 'vt8500_ports_in_use' being a 'unsigned long', use ffz to reduce
    code verbosity
  - VT8500_MAX_PORTS, in order to be consistent with the test below
---
 drivers/tty/serial/vt8500_serial.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 23cfc5e16b45..935076c50cb1 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -664,7 +664,7 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	if (port < 0) {
 		/* calculate the port id */
 		port = find_first_zero_bit(&vt8500_ports_in_use,
-					sizeof(vt8500_ports_in_use));
+					   BITS_PER_LONG);
 	}
 
 	if (port >= VT8500_MAX_PORTS)
-- 
2.7.4


---
L'absence de virus dans ce courrier ?lectronique a ?t? v?rifi?e par le logiciel antivirus Avast.
https://www.avast.com/antivirus
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help