* [PATCH] kernel: time: timer.c: use __fls in apply_slack()
@ 2015-10-02 7:45 Rasmus Villemoes
2015-10-11 20:09 ` [tip:timers/core] timers: Use " tip-bot for Rasmus Villemoes
2015-10-11 20:15 ` tip-bot for Rasmus Villemoes
0 siblings, 2 replies; 3+ messages in thread
From: Rasmus Villemoes @ 2015-10-02 7:45 UTC (permalink / raw)
To: John Stultz, Thomas Gleixner; +Cc: Rasmus Villemoes, linux-kernel
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@rasmusvillemoes.dk>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [tip:timers/core] timers: Use __fls in apply_slack()
2015-10-02 7:45 [PATCH] kernel: time: timer.c: use __fls in apply_slack() Rasmus Villemoes
@ 2015-10-11 20:09 ` tip-bot for Rasmus Villemoes
2015-10-11 20:15 ` tip-bot for Rasmus Villemoes
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Rasmus Villemoes @ 2015-10-11 20:09 UTC (permalink / raw)
To: linux-tip-commits; +Cc: tglx, mingo, linux, linux-kernel, hpa, john.stultz
Commit-ID: 3e17510cbc3e75cae0c96fa38ca469ffe754aedf
Gitweb: http://git.kernel.org/tip/3e17510cbc3e75cae0c96fa38ca469ffe754aedf
Author: Rasmus Villemoes <linux@rasmusvillemoes.dk>
AuthorDate: Fri, 2 Oct 2015 09:45:30 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 11 Oct 2015 22:07:23 +0200
timers: Use __fls in apply_slack()
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@rasmusvillemoes.dk>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1443771931-6284-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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 d3f5e92..74591ba 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -874,7 +874,7 @@ 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;
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [tip:timers/core] timers: Use __fls in apply_slack()
2015-10-02 7:45 [PATCH] kernel: time: timer.c: use __fls in apply_slack() Rasmus Villemoes
2015-10-11 20:09 ` [tip:timers/core] timers: Use " tip-bot for Rasmus Villemoes
@ 2015-10-11 20:15 ` tip-bot for Rasmus Villemoes
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Rasmus Villemoes @ 2015-10-11 20:15 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux, mingo, hpa, john.stultz, linux-kernel, tglx
Commit-ID: 9fc4468d546b6eb55b0aa5b04b0c36238ebf57e7
Gitweb: http://git.kernel.org/tip/9fc4468d546b6eb55b0aa5b04b0c36238ebf57e7
Author: Rasmus Villemoes <linux@rasmusvillemoes.dk>
AuthorDate: Fri, 2 Oct 2015 09:45:30 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 11 Oct 2015 22:13:46 +0200
timers: Use __fls in apply_slack()
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@rasmusvillemoes.dk>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1443771931-6284-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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 d3f5e92..74591ba 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -874,7 +874,7 @@ 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;
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-10-11 20:16 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2015-10-02 7:45 [PATCH] kernel: time: timer.c: use __fls in apply_slack() Rasmus Villemoes
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2015-10-11 20:15 ` tip-bot for Rasmus Villemoes
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