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lib: count_zeros: unify count_{leading,trailing}_zeros()

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The 'leading' helper returns BITS_PER_LONG if x == 0, while 'trailing'
one returns COUNT_TRAILING_ZEROS_0, which turns to be -1.

None of the current users explicitly check the returned value for
COUNT_TRAILING_ZEROS_0, except the loongarch, which tests implicitly
for the '>= 0'.

So, align count_trailing_zeros() with the count_leading_zeros(), and
simplify the loongarch handling.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
This commit is contained in:
Yury Norov
2026-03-23 12:17:12 -04:00
parent 4e64c91b81
commit be56db15fc
2 changed files with 4 additions and 6 deletions
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4
arch/loongarch/kvm/intc/eiointc.c
View File

@@ -16,7 +16,7 @@ static void eiointc_set_sw_coreisr(struct loongarch_eiointc *s)
ipnum = (s->ipmap >> (irq / 32 * 8)) & 0xff;
if (!(s->status & BIT(EIOINTC_ENABLE_INT_ENCODE))) {
ipnum = count_trailing_zeros(ipnum);
ipnum = (ipnum >= 0 && ipnum < 4) ? ipnum : 0;
ipnum = ipnum < 4 ? ipnum : 0;
}
cpuid = ((u8 *)s->coremap)[irq];
@@ -41,7 +41,7 @@ static void eiointc_update_irq(struct loongarch_eiointc *s, int irq, int level)
ipnum = (s->ipmap >> (irq / 32 * 8)) & 0xff;
if (!(s->status & BIT(EIOINTC_ENABLE_INT_ENCODE))) {
ipnum = count_trailing_zeros(ipnum);
ipnum = (ipnum >= 0 && ipnum < 4) ? ipnum : 0;
ipnum = ipnum < 4 ? ipnum : 0;
}
cpu = s->sw_coremap[irq];

6
include/linux/count_zeros.h
View File

@@ -10,8 +10,6 @@
#include <asm/bitops.h>
#define COUNT_TRAILING_ZEROS_0 (-1)
/**
* count_leading_zeros - Count the number of zeros from the MSB back
* @x: The value
@@ -38,11 +36,11 @@ static inline int count_leading_zeros(unsigned long x)
*
* If the LSB of @x is set, the result is 0.
* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
* If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.
* If @x is 0 then the result is BITS_PER_LONG.
*/
static inline int count_trailing_zeros(unsigned long x)
{
return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;
return x ? __ffs(x) : BITS_PER_LONG;
}
#endif /* _LINUX_BITOPS_COUNT_ZEROS_H_ */