The patch titled
Subject: lib/group_cpus: relax atomicity requirement in grp_spread_init_one()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-group_cpus-relax-atomicity-requirement-in-grp_spread_init_one.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-group_cpus-relax-atomicity-requirement-in-grp_spread_init_one.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: Yury Norov <yury.norov@xxxxxxxxx>
Subject: lib/group_cpus: relax atomicity requirement in grp_spread_init_one()
Date: Thu, 28 Dec 2023 12:09:30 -0800
Because nmsk and irqmsk are stable, extra atomicity is not required.
__cpumask_clear_cpu() and __cpumask_set_cpu() are added in commit
6c8557bdb28d ("smp, cpumask: Use non-atomic cpumask_{set,clear}_cpu()")
for fast code path( smp_call_function_many()).
We have ~670 users of cpumask_clear_cpu & cpumask_set_cpu, lots of them
fall into same category with group_cpus.c(doesn't care atomicity, not in
fast code path), and needn't change to __cpumask_clear_cpu() and
__cpumask_set_cpu(). Otherwise, this way may encourage to update others
into the __cpumask_* version.
Link: https://lkml.kernel.org/r/20231228200936.2475595-4-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
NAKed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/group_cpus.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/lib/group_cpus.c~lib-group_cpus-relax-atomicity-requirement-in-grp_spread_init_one
+++ a/lib/group_cpus.c
@@ -24,8 +24,8 @@ static void grp_spread_init_one(struct c
if (cpu >= nr_cpu_ids)
return;
- cpumask_clear_cpu(cpu, nmsk);
- cpumask_set_cpu(cpu, irqmsk);
+ __cpumask_clear_cpu(cpu, nmsk);
+ __cpumask_set_cpu(cpu, irqmsk);
cpus_per_grp--;
/* If the cpu has siblings, use them first */
@@ -36,8 +36,8 @@ static void grp_spread_init_one(struct c
if (cpus_per_grp-- == 0)
return;
- cpumask_clear_cpu(sibl, nmsk);
- cpumask_set_cpu(sibl, irqmsk);
+ __cpumask_clear_cpu(sibl, nmsk);
+ __cpumask_set_cpu(sibl, irqmsk);
}
}
}
_
Patches currently in -mm which might be from yury.norov@xxxxxxxxx are
cpumask-introduce-for_each_cpu_and_from.patch
lib-group_cpus-optimize-inner-loop-in-grp_spread_init_one.patch
lib-group_cpus-relax-atomicity-requirement-in-grp_spread_init_one.patch
lib-group_cpus-optimize-outer-loop-in-grp_spread_init_one.patch
lib-group_cpus-dont-zero-cpumasks-in-group_cpus_evenly-on-allocation.patch
lib-group_cpus-drop-unneeded-cpumask_empty-call-in-__group_cpus_evenly.patch
cpumask-define-cleanup-function-for-cpumasks.patch
lib-group_cpus-rework-group_cpus_evenly.patch
lib-group_cpus-simplify-group_cpus_evenly-for-more.patch
