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) <[email protected]> --- include/linux/cpumask.h | 20 ++++++++++++++++++++ kernel/cpu.c | 6 ++++++ 2 files changed, 26 insertions(+) --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -91,10 +91,12 @@ extern struct cpumask __cpu_possible_mas extern struct cpumask __cpu_online_mask; extern struct cpumask __cpu_present_mask; extern struct cpumask __cpu_active_mask; +extern struct cpumask __cpu_dying_mask; #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask) #define cpu_online_mask ((const struct cpumask *)&__cpu_online_mask) #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) +#define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) extern atomic_t __num_online_cpus; @@ -826,6 +828,14 @@ set_cpu_active(unsigned int cpu, bool ac cpumask_clear_cpu(cpu, &__cpu_active_mask); } +static inline void +set_cpu_dying(unsigned int cpu, bool dying) +{ + if (dying) + cpumask_set_cpu(cpu, &__cpu_dying_mask); + else + cpumask_clear_cpu(cpu, &__cpu_dying_mask); +} /** * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask * @@ -900,6 +910,11 @@ static inline bool cpu_active(unsigned i return cpumask_test_cpu(cpu, cpu_active_mask); } +static inline bool cpu_dying(unsigned int cpu) +{ + return cpumask_test_cpu(cpu, cpu_dying_mask); +} + #else #define num_online_cpus() 1U @@ -927,6 +942,11 @@ static inline bool cpu_active(unsigned i return cpu == 0; } +static inline bool cpu_dying(unsigned int cpu) +{ + return false; +} + #endif /* NR_CPUS > 1 */ #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu)) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -160,6 +160,9 @@ static int cpuhp_invoke_callback(unsigne int (*cb)(unsigned int cpu); int ret, cnt; + if (bringup != !cpu_dying(cpu)) + 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);
