Messages in this thread Patch in this message | | | Subject | Re: [PATCH 04/10] omap_hwspinlock: Replace "hweight_long(i & 0xf) != 1" with "!is_power_of_2(i & 0xf)" | From | "zhaoxiu.zeng" <> | Date | Mon, 7 Dec 2015 23:03:30 +0800 |
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在 2015/12/7 19:08, Ohad Ben-Cohen 写道: > Hi, > > On Sun, Dec 6, 2015 at 12:33 PM, Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com> wrote: >> >> From: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com> >> >> Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com> > > Please explain why do you think we should make this change.
is_power_of_2 is simple, and faster than "hweightN(x) == 1" on most architectures. And the "& 0xf" operation is unnecessary, we will check whether or not greater than 8 behind.
> > Btw, the original code used is_power_of_2, but we thought hweight is > more explicit so it was adopted. > > Thanks, > Ohad. >
--- drivers/hwspinlock/omap_hwspinlock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c index ad2f8ca..1848a4c 100644 --- a/drivers/hwspinlock/omap_hwspinlock.c +++ b/drivers/hwspinlock/omap_hwspinlock.c @@ -29,6 +29,7 @@ #include <linux/hwspinlock.h> #include <linux/of.h> #include <linux/platform_device.h> +#include <linux/log2.h> #include "hwspinlock_internal.h" @@ -125,7 +126,7 @@ static int omap_hwspinlock_probe(struct platform_device *pdev) goto iounmap_base; /* one of the four lsb's must be set, and nothing else */ - if (hweight_long(i & 0xf) != 1 || i > 8) { + if (!is_power_of_2(i) || i > 8) { ret = -EINVAL; goto iounmap_base; } --
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