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lib/cpumask: add inline cpumask_next_wrap() for UP

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In the uniprocessor case, cpumask_next_wrap() can be simplified, as the
number of valid argument combinations is limited:
    - 'start' can only be 0
    - 'n' can only be -1 or 0

The only valid CPU that can then be returned, if any, will be the first
one set in the provided 'mask'.

For NR_CPUS == 1, include/linux/cpumask.h now provides an inline
definition of cpumask_next_wrap(), which will conflict with the one
provided by lib/cpumask.c.  Make building of lib/cpumask.o again depend
on CONFIG_SMP=y (i.e. NR_CPUS > 1) to avoid the re-definition.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
This commit is contained in:
Sander Vanheule 2022-08-09 19:36:34 +02:00 committed by Yury Norov
parent be59924486
commit 2248ccd801
2 changed files with 21 additions and 1 deletions
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19
include/linux/cpumask.h
View File

@ -262,7 +262,26 @@ unsigned int cpumask_next_and(int n, const struct cpumask *src1p,
(cpu) = cpumask_next_zero((cpu), (mask)), \
(cpu) < nr_cpu_ids;)
#if NR_CPUS == 1
static inline
unsigned int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
{
cpumask_check(start);
if (n != -1)
cpumask_check(n);
/*
* Return the first available CPU when wrapping, or when starting before cpu0,
* since there is only one valid option.
*/
if (wrap && n >= 0)
return nr_cpumask_bits;
return cpumask_first(mask);
}
#else
unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap);
#endif
/**
* for_each_cpu_wrap - iterate over every cpu in a mask, starting at a specified location

3
lib/Makefile
View File

@ -34,9 +34,10 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
nmi_backtrace.o win_minmax.o memcat_p.o \
buildid.o cpumask.o
buildid.o
lib-$(CONFIG_PRINTK) += dump_stack.o
lib-$(CONFIG_SMP) += cpumask.o
lib-y += kobject.o klist.o
obj-y += lockref.o