The following commit has been merged into the core/rcu branch of tip: Commit-ID: b1fcf9b83c4149c63d1e0c699e85f93cbe28e211 Gitweb: https://git.kernel.org/tip/b1fcf9b83c4149c63d1e0c699e85f93cbe28e211 Author: Thomas Gleixner <[email protected]> AuthorDate: Tue, 12 May 2020 09:44:43 +02:00 Committer: Thomas Gleixner <[email protected]> CommitterDate: Tue, 19 May 2020 15:51:21 +02:00
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: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- include/linux/rcutiny.h | 1 + include/linux/rcutree.h | 1 + kernel/rcu/tree.c | 5 +++++ 3 files changed, 7 insertions(+) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 980eb78..c869fb2 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -86,6 +86,7 @@ static inline void rcu_scheduler_starting(void) { } static inline void rcu_end_inkernel_boot(void) { } 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 void rcu_momentary_dyntick_idle(void) { } static inline void kfree_rcu_scheduler_running(void) { } static inline bool rcu_gp_might_be_stalled(void) { return false; } diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 02016e0..9366fa4 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -58,6 +58,7 @@ extern int rcu_scheduler_active __read_mostly; void rcu_end_inkernel_boot(void); bool rcu_inkernel_boot_has_ended(void); bool rcu_is_watching(void); +bool __rcu_is_watching(void); #ifndef CONFIG_PREEMPTION void rcu_all_qs(void); #endif diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 62ee012..90c8be2 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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 *
