cpumask: Introduce DYING mask

mainline inclusion
from mainline-v5.13-rc1
commit e40f74c5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6VS35

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e40f74c535b8a0ecf3ef0388b51a34cdadb34fb5

--------------------------------

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: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NValentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210310150109.151441252@infradead.orgSigned-off-by: NZeng Heng <zengheng4@huawei.com>

include/linux/cpumask.h

@@ -91,10 +91,12 @@ extern struct cpumask __cpu_possible_mask;
 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;
 
@@ -118,6 +120,11 @@ static inline unsigned int num_online_cpus(void)
 #define cpu_possible(cpu)	cpumask_test_cpu((cpu), cpu_possible_mask)
 #define cpu_present(cpu)	cpumask_test_cpu((cpu), cpu_present_mask)
 #define cpu_active(cpu)		cpumask_test_cpu((cpu), cpu_active_mask)
+static inline int cpumask_test_cpu(int cpu, const struct cpumask *cpumask);
+static inline bool cpu_dying(unsigned int cpu)
+{
+	return cpumask_test_cpu(cpu, cpu_dying_mask);
+}
 #else
 #define num_online_cpus()	1U
 #define num_possible_cpus()	1U
@@ -127,6 +134,10 @@ static inline unsigned int num_online_cpus(void)
 #define cpu_possible(cpu)	((cpu) == 0)
 #define cpu_present(cpu)	((cpu) == 0)
 #define cpu_active(cpu)		((cpu) == 0)
+static inline bool cpu_dying(unsigned int cpu)
+{
+	return false;
+}
 #endif
 
 extern cpumask_t cpus_booted_once_mask;
@@ -851,6 +862,14 @@ set_cpu_active(unsigned int cpu, bool active)
 		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 *

kernel/cpu.c

@@ -157,6 +157,9 @@ 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;
 
@@ -2502,6 +2505,9 @@ 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);