6.6-stable review patch. If anyone has any objections, please let me know.
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From: Frederic Weisbecker frederic@kernel.org
[ Upstream commit 2be4686d866ad5896f2bb94d82fe892197aea9c7 ]
Export the RCU point of view as to when a CPU is considered offline (ie: when does RCU consider that a CPU is sufficiently down in the hotplug process to not feature any possible read side).
This will be used by RCU-tasks whose vision of an offline CPU should reasonably match the one of RCU core.
Fixes: cff9b2332ab7 ("kernel/sched: Modify initial boot task idle setup") Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Frederic Weisbecker frederic@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/rcu/rcu.h | 2 ++ kernel/rcu/tree.c | 7 +++++++ 2 files changed, 9 insertions(+)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 98e13be411afd..3d1851f82dbb6 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -493,6 +493,7 @@ static inline void rcu_expedite_gp(void) { } static inline void rcu_unexpedite_gp(void) { } static inline void rcu_async_hurry(void) { } static inline void rcu_async_relax(void) { } +static inline bool rcu_cpu_online(int cpu) { return true; } #else /* #ifdef CONFIG_TINY_RCU */ bool rcu_gp_is_normal(void); /* Internal RCU use. */ bool rcu_gp_is_expedited(void); /* Internal RCU use. */ @@ -502,6 +503,7 @@ void rcu_unexpedite_gp(void); void rcu_async_hurry(void); void rcu_async_relax(void); void rcupdate_announce_bootup_oddness(void); +bool rcu_cpu_online(int cpu); #ifdef CONFIG_TASKS_RCU_GENERIC void show_rcu_tasks_gp_kthreads(void); #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 92a090e161865..9af42eae1ba38 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4139,6 +4139,13 @@ static bool rcu_rdp_cpu_online(struct rcu_data *rdp) return !!(rdp->grpmask & rcu_rnp_online_cpus(rdp->mynode)); }
+bool rcu_cpu_online(int cpu) +{ + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); + + return rcu_rdp_cpu_online(rdp); +} + #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
/*