[PATCH] kernel: time: timer.c: use __fls in apply_slack()

From: Rasmus Villemoes
Date: Fri Oct 02 2015 - 03:45:50 EST


In apply_slack(), find_last_bit() is applied to a bitmask consisting
of precisely BITS_PER_LONG bits. Since mask is non-zero, we might as
well eliminate the function call and use __fls() directly. On x86_64,
this shaves 23 bytes of the only caller, mod_timer().

This also gets rid of Coverity CID 1192106, but that is a false
positive: Coverity is not aware that mask != 0 implies that
find_last_bit will not return BITS_PER_LONG.

Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
kernel/time/timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 84190f02b521..71eb089d1030 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -867,7 +867,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
if (mask == 0)
return expires;

- bit = find_last_bit(&mask, BITS_PER_LONG);
+ bit = __fls(mask);

mask = (1UL << bit) - 1;

--
2.1.3

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