From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> [ Upstream commit c743f0a5c50f2fcbc628526279cfa24f3dabe182 ] More users for for_each_cpu_wrap() have appeared. Promote the construct to generic cpumask interface. The implementation is slightly modified to reduce arguments. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Lauro Ramos Venancio <lvenanci@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: lwang@xxxxxxxxxx Link: http://lkml.kernel.org/r/20170414122005.o35me2h5nowqkxbv@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> [dj: include only what's added to the cpumask interface, 4.4 doesn't have them in the scheduler] Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx> --- include/linux/cpumask.h | 17 +++++++++++++++++ lib/cpumask.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index bb3a4bb35183..1322883e7b46 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -232,6 +232,23 @@ unsigned int cpumask_local_spread(unsigned int i, int node); (cpu) = cpumask_next_zero((cpu), (mask)), \ (cpu) < nr_cpu_ids;) +extern int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap); + +/** + * for_each_cpu_wrap - iterate over every cpu in a mask, starting at a specified location + * @cpu: the (optionally unsigned) integer iterator + * @mask: the cpumask poiter + * @start: the start location + * + * The implementation does not assume any bit in @mask is set (including @start). + * + * After the loop, cpu is >= nr_cpu_ids. + */ +#define for_each_cpu_wrap(cpu, mask, start) \ + for ((cpu) = cpumask_next_wrap((start)-1, (mask), (start), false); \ + (cpu) < nr_cpumask_bits; \ + (cpu) = cpumask_next_wrap((cpu), (mask), (start), true)) + /** * for_each_cpu_and - iterate over every cpu in both masks * @cpu: the (optionally unsigned) integer iterator diff --git a/lib/cpumask.c b/lib/cpumask.c index 5a70f6196f57..24f06e7abf92 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -42,6 +42,38 @@ int cpumask_any_but(const struct cpumask *mask, unsigned int cpu) return i; } +/** + * cpumask_next_wrap - helper to implement for_each_cpu_wrap + * @n: the cpu prior to the place to search + * @mask: the cpumask pointer + * @start: the start point of the iteration + * @wrap: assume @n crossing @start terminates the iteration + * + * Returns >= nr_cpu_ids on completion + * + * Note: the @wrap argument is required for the start condition when + * we cannot assume @start is set in @mask. + */ +int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap) +{ + int next; + +again: + next = cpumask_next(n, mask); + + if (wrap && n < start && next >= start) { + return nr_cpumask_bits; + + } else if (next >= nr_cpumask_bits) { + wrap = true; + n = -1; + goto again; + } + + return next; +} +EXPORT_SYMBOL(cpumask_next_wrap); + /* These are not inline because of header tangles. */ #ifdef CONFIG_CPUMASK_OFFSTACK /** -- 2.26.2
