From: Patrick McHardy <[EMAIL PROTECTED]>
Date: Mon, 21 Jan 2008 01:16:32 +0100
> Stephen Hemminger wrote:
> > Replace loop in dsmark_valid_indices with equivalent bit math.
> >
> > Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
> >
> > --- a/net/sched/sch_dsmark.c 2008-01-20 13:07:58.000000000 -0800
> > +++ b/net/sched/sch_dsmark.c 2008-01-20 13:22:54.000000000 -0800
> > @@ -45,13 +45,8 @@ struct dsmark_qdisc_data {
> >
> > static inline int dsmark_valid_indices(u16 indices)
> > {
> > - while (indices != 1) {
> > - if (indices & 1)
> > - return 0;
> > - indices >>= 1;
> > - }
> > -
> > - return 1;
> > + /* Must have only one bit set */
> > + return (indices & (indices - 1)) == 0;
>
> hweight seems easier to understand, it took me a bit
> to realize that the comment matches the code :)
Sounds good. Here is what I ended up checking in.
[PKT_SCHED] dsmark: Use hweight32() instead of convoluted loop.
Based upon a patch by Stephen Hemminger and suggestions
from Patrick McHardy.
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c
index a9732ae..d96eaf0 100644
--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -10,6 +10,7 @@
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
+#include <linux/bitops.h>
#include <net/pkt_sched.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
@@ -43,17 +44,6 @@ struct dsmark_qdisc_data {
int set_tc_index;
};
-static inline int dsmark_valid_indices(u16 indices)
-{
- while (indices != 1) {
- if (indices & 1)
- return 0;
- indices >>= 1;
- }
-
- return 1;
-}
-
static inline int dsmark_valid_index(struct dsmark_qdisc_data *p, u16 index)
{
return (index <= p->indices && index > 0);
@@ -348,7 +338,8 @@ static int dsmark_init(struct Qdisc *sch, struct rtattr
*opt)
goto errout;
indices = RTA_GET_U16(tb[TCA_DSMARK_INDICES-1]);
- if (!indices || !dsmark_valid_indices(indices))
+
+ if (hweight32(indices) != 1)
goto errout;
if (tb[TCA_DSMARK_DEFAULT_INDEX-1])
--
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