Commit b1fcf9b8 authored by Thomas Gleixner's avatar Thomas Gleixner

rcu: Provide __rcu_is_watching()

Same as rcu_is_watching() but without the preempt_disable/enable() pair
inside the function. It is merked noinstr so it ends up in the
non-instrumentable text section.

This is useful for non-preemptible code especially in the low level entry
section. Using rcu_is_watching() there results in a call to the
preempt_schedule_notrace() thunk which triggers noinstr section warnings in
objtool.
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200512213810.518709291@linutronix.de
parent 8ae0ae67
...@@ -86,6 +86,7 @@ static inline void rcu_scheduler_starting(void) { } ...@@ -86,6 +86,7 @@ static inline void rcu_scheduler_starting(void) { }
static inline void rcu_end_inkernel_boot(void) { } static inline void rcu_end_inkernel_boot(void) { }
static inline bool rcu_inkernel_boot_has_ended(void) { return true; } static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
static inline bool rcu_is_watching(void) { return true; } static inline bool rcu_is_watching(void) { return true; }
static inline bool __rcu_is_watching(void) { return true; }
static inline void rcu_momentary_dyntick_idle(void) { } static inline void rcu_momentary_dyntick_idle(void) { }
static inline void kfree_rcu_scheduler_running(void) { } static inline void kfree_rcu_scheduler_running(void) { }
static inline bool rcu_gp_might_be_stalled(void) { return false; } static inline bool rcu_gp_might_be_stalled(void) { return false; }
......
...@@ -58,6 +58,7 @@ extern int rcu_scheduler_active __read_mostly; ...@@ -58,6 +58,7 @@ extern int rcu_scheduler_active __read_mostly;
void rcu_end_inkernel_boot(void); void rcu_end_inkernel_boot(void);
bool rcu_inkernel_boot_has_ended(void); bool rcu_inkernel_boot_has_ended(void);
bool rcu_is_watching(void); bool rcu_is_watching(void);
bool __rcu_is_watching(void);
#ifndef CONFIG_PREEMPTION #ifndef CONFIG_PREEMPTION
void rcu_all_qs(void); void rcu_all_qs(void);
#endif #endif
......
...@@ -985,6 +985,11 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp) ...@@ -985,6 +985,11 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp)
} }
} }
noinstr bool __rcu_is_watching(void)
{
return !rcu_dynticks_curr_cpu_in_eqs();
}
/** /**
* rcu_is_watching - see if RCU thinks that the current CPU is not idle * rcu_is_watching - see if RCU thinks that the current CPU is not idle
* *
......
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