diff options
| -rw-r--r-- | include/linux/rcupdate.h | 11 | ||||
| -rw-r--r-- | include/linux/rcutiny.h | 13 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 5 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 22 | ||||
| -rw-r--r-- | kernel/rcu/update.c | 1 | ||||
| -rw-r--r-- | kernel/sched/core.c | 2 |
6 files changed, 43 insertions, 11 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index e6146d0074f8..f531b29207da 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -363,15 +363,20 @@ static inline void rcu_init_nohz(void) #ifdef CONFIG_TASKS_RCU #define TASKS_RCU(x) x extern struct srcu_struct tasks_rcu_exit_srcu; -#define rcu_note_voluntary_context_switch(t) \ +#define rcu_note_voluntary_context_switch_lite(t) \ do { \ - rcu_all_qs(); \ if (READ_ONCE((t)->rcu_tasks_holdout)) \ WRITE_ONCE((t)->rcu_tasks_holdout, false); \ } while (0) +#define rcu_note_voluntary_context_switch(t) \ + do { \ + rcu_all_qs(); \ + rcu_note_voluntary_context_switch_lite(t); \ + } while (0) #else /* #ifdef CONFIG_TASKS_RCU */ #define TASKS_RCU(x) do { } while (0) -#define rcu_note_voluntary_context_switch(t) rcu_all_qs() +#define rcu_note_voluntary_context_switch_lite(t) do { } while (0) +#define rcu_note_voluntary_context_switch(t) rcu_all_qs() #endif /* #else #ifdef CONFIG_TASKS_RCU */ /** diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 5219be250f00..74d9c3a1feee 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -92,10 +92,11 @@ static inline void kfree_call_rcu(struct rcu_head *head, call_rcu(head, func); } -static inline void rcu_note_context_switch(void) -{ - rcu_sched_qs(); -} +#define rcu_note_context_switch(preempt) \ + do { \ + rcu_sched_qs(); \ + rcu_note_voluntary_context_switch_lite(current); \ + } while (0) /* * Take advantage of the fact that there is only one CPU, which @@ -242,6 +243,10 @@ static inline bool rcu_is_watching(void) #endif /* #else defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */ +static inline void rcu_request_urgent_qs_task(struct task_struct *t) +{ +} + static inline void rcu_all_qs(void) { barrier(); /* Avoid RCU read-side critical sections leaking across. */ diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 63a4e4cf40a5..0bacb6b2af69 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -30,7 +30,7 @@ #ifndef __LINUX_RCUTREE_H #define __LINUX_RCUTREE_H -void rcu_note_context_switch(void); +void rcu_note_context_switch(bool preempt); int rcu_needs_cpu(u64 basem, u64 *nextevt); void rcu_cpu_stall_reset(void); @@ -41,7 +41,7 @@ void rcu_cpu_stall_reset(void); */ static inline void rcu_virt_note_context_switch(int cpu) { - rcu_note_context_switch(); + rcu_note_context_switch(false); } void synchronize_rcu_bh(void); @@ -108,6 +108,7 @@ void rcu_scheduler_starting(void); extern int rcu_scheduler_active __read_mostly; bool rcu_is_watching(void); +void rcu_request_urgent_qs_task(struct task_struct *t); void rcu_all_qs(void); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 3c23435d2083..891d97109e09 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -458,7 +458,7 @@ static void rcu_momentary_dyntick_idle(void) * and requires special handling for preemptible RCU. * The caller must have disabled interrupts. */ -void rcu_note_context_switch(void) +void rcu_note_context_switch(bool preempt) { barrier(); /* Avoid RCU read-side critical sections leaking down. */ trace_rcu_utilization(TPS("Start context switch")); @@ -471,6 +471,8 @@ void rcu_note_context_switch(void) if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) rcu_momentary_dyntick_idle(); this_cpu_inc(rcu_dynticks.rcu_qs_ctr); + if (!preempt) + rcu_note_voluntary_context_switch_lite(current); out: trace_rcu_utilization(TPS("End context switch")); barrier(); /* Avoid RCU read-side critical sections leaking up. */ @@ -1149,6 +1151,24 @@ bool notrace rcu_is_watching(void) } EXPORT_SYMBOL_GPL(rcu_is_watching); +/* + * If a holdout task is actually running, request an urgent quiescent + * state from its CPU. This is unsynchronized, so migrations can cause + * the request to go to the wrong CPU. Which is OK, all that will happen + * is that the CPU's next context switch will be a bit slower and next + * time around this task will generate another request. + */ +void rcu_request_urgent_qs_task(struct task_struct *t) +{ + int cpu; + + barrier(); + cpu = task_cpu(t); + if (!task_curr(t)) + return; /* This task is not running on that CPU. */ + smp_store_release(per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, cpu), true); +} + #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) /* diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index c5df0d756900..273e869ca21d 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -665,6 +665,7 @@ static void check_holdout_task(struct task_struct *t, put_task_struct(t); return; } + rcu_request_urgent_qs_task(t); if (!needreport) return; if (*firstreport) { diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 3b31fc05a0f1..2adf7b6c04e7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3378,7 +3378,7 @@ static void __sched notrace __schedule(bool preempt) hrtick_clear(rq); local_irq_disable(); - rcu_note_context_switch(); + rcu_note_context_switch(preempt); /* * Make sure that signal_pending_state()->signal_pending() below |