diff options
| author | Sander Vanheule <[email protected]> | 2022-07-02 18:08:27 +0200 |
|---|---|---|
| committer | akpm <[email protected]> | 2022-07-17 17:31:41 -0700 |
| commit | 4f09903078eeb9138cddce8db06100b82f8620e8 (patch) | |
| tree | 8149215e5778d6616761afa3fe0793ff509dbca0 | |
| parent | adbcaef84088713bae9af5690cf566ce4fadfa22 (diff) | |
cpumask: add UP optimised for_each_*_cpu versions
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.
Link: https://lkml.kernel.org/r/3a92869b902a075b97be5d1452c9c6badbbff0df.1656777646.git.sander@svanheule.net
Signed-off-by: Sander Vanheule <[email protected]>
Acked-by: Yury Norov <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
| -rw-r--r-- | include/linux/cpumask.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index fe29ac7cc469..533612770bc0 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -811,9 +811,16 @@ 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); |