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cpumask: Introduce DYING mask

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Introduce a cpumask that indicates (for each CPU) what direction the
CPU hotplug is currently going. Notably, it tracks rollbacks. Eg. when
an up fails and we do a roll-back down, it will accurately reflect the
direction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210310150109.151441252@infradead.org
This commit is contained in:
Peter Zijlstra
2021-01-19 18:43:45 +01:00
parent b02a4fd814
commit e40f74c535
2 changed files with 26 additions and 0 deletions
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6
kernel/cpu.c
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@ -160,6 +160,9 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
int (*cb)(unsigned int cpu);
int ret, cnt;
if (cpu_dying(cpu) != !bringup)
set_cpu_dying(cpu, !bringup);
if (st->fail == state) {
st->fail = CPUHP_INVALID;
return -EAGAIN;
@ -2512,6 +2515,9 @@ EXPORT_SYMBOL(__cpu_present_mask);
struct cpumask __cpu_active_mask __read_mostly;
EXPORT_SYMBOL(__cpu_active_mask);
struct cpumask __cpu_dying_mask __read_mostly;
EXPORT_SYMBOL(__cpu_dying_mask);
atomic_t __num_online_cpus __read_mostly;
EXPORT_SYMBOL(__num_online_cpus);