The patch titled
Subject: cpumask: add UP optimised for_each_*_cpu versions
has been added to the -mm mm-nonmm-unstable branch. Its filename is
cpumask-add-up-optimised-for_each__cpu-versions.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/cpumask-add-up-optimised-for_each__cpu-versions.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sander Vanheule <sander@xxxxxxxxxxxxx>
Subject: cpumask: add UP optimised for_each_*_cpu versions
Date: Sat, 2 Jul 2022 18:08:27 +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.
Link: https://lkml.kernel.org/r/3a92869b902a075b97be5d1452c9c6badbbff0df.1656777646.git.sander@xxxxxxxxxxxxx
Signed-off-by: Sander Vanheule <sander@xxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Yury Norov <yury.norov@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cpumask.h | 7 +++++++
1 file changed, 7 insertions(+)
--- a/include/linux/cpumask.h~cpumask-add-up-optimised-for_each__cpu-versions
+++ a/include/linux/cpumask.h
@@ -750,9 +750,16 @@ extern const DECLARE_BITMAP(cpu_all_bits
/* 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);
_
Patches currently in -mm which might be from sander@xxxxxxxxxxxxx are
x86-cacheinfo-move-shared-cache-map-definitions.patch
cpumask-fix-invalid-uniprocessor-mask-assumption.patch
lib-test-introduce-cpumask-kunit-test-suite.patch
cpumask-add-up-optimised-for_each__cpu-versions.patch
cpumask-update-cpumask_next_wrap-signature.patch
