Messages in this thread Patch in this message | | | From | Sander Vanheule <> | Subject | [PATCH v3 3/4] cpumask: Add UP optimised for_each_*_cpu versions | Date | Sun, 5 Jun 2022 08:22:40 +0200 |
| |
On uniprocessor builds, the following loops will always run over a mask that contains one enabled CPU (cpu0): - for_each_possible_cpu - for_each_online_cpu - for_each_present_cpu
Provide uniprocessor-specific macros for these loops, that always run exactly once.
Signed-off-by: Sander Vanheule <sander@svanheule.net> --- include/linux/cpumask.h | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index d6add0e29ef4..7ccddbc27ac3 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -731,9 +731,16 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); /* First bits of cpu_bit_bitmap are in fact unset. */ #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0]) +#if NR_CPUS == 1 +/* Uniprocessor: the possible/online/present masks are always "1" */ +#define for_each_possible_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#define for_each_online_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#define for_each_present_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#else #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask) #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask) #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask) +#endif /* Wrappers for arch boot code to manipulate normally-constant masks */ void init_cpu_present(const struct cpumask *src); -- 2.36.1
| |