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charset="utf-8" Use a bit in rseq flags to indicate if the thread got rescheduled after the cpu time extension was graned. The user thread can check this flag before calling sched_yield() to yield the cpu. Signed-off-by: Prakash Sangappa --- include/linux/sched.h | 2 ++ include/uapi/linux/rseq.h | 10 ++++++++++ kernel/rseq.c | 20 ++++++++++++++++++++ kernel/sched/core.c | 3 +-- 4 files changed, 33 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 14bf0508bfca..71e6c8221c1e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2256,12 +2256,14 @@ unsigned long sched_cpu_util(int cpu); extern bool rseq_delay_resched(void); extern void rseq_delay_resched_fini(void); extern void rseq_delay_resched_tick(void); +extern void rseq_delay_schedule(void); =20 #else =20 static inline bool rseq_delay_resched(void) { return false; } static inline void rseq_delay_resched_fini(void) { } static inline void rseq_delay_resched_tick(void) { } +static inline void rseq_delay_schedule(void) { } =20 #endif =20 diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index 25fc636b17d5..f4813d931387 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -27,6 +27,7 @@ enum rseq_cs_flags_bit { RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT =3D 1, RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT =3D 2, RSEQ_CS_FLAG_DELAY_RESCHED_BIT =3D 3, + RSEQ_CS_FLAG_RESCHEDULED_BIT =3D 4, }; =20 enum rseq_cs_flags { @@ -38,6 +39,9 @@ enum rseq_cs_flags { (1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT), RSEQ_CS_FLAG_DELAY_RESCHED =3D (1U << RSEQ_CS_FLAG_DELAY_RESCHED_BIT), + RSEQ_CS_FLAG_RESCHEDULED =3D + (1U << RSEQ_CS_FLAG_RESCHEDULED_BIT), + }; =20 /* @@ -135,6 +139,12 @@ struct rseq { * Request by user thread to delay preemption. With use * of a timer, kernel grants extra cpu time upto 30us for this * thread before being rescheduled. + * - RSEQ_CS_FLAG_RESCHEDULED + * Set by kernel if the thread was rescheduled in the extra time + * granted due to request RSEQ_CS_DELAY_RESCHED. This bit is + * checked by the thread before calling sched_yield() to yield + * cpu. User thread sets this bit to 0, when setting + * RSEQ_CS_DELAY_RESCHED to request preemption delay. */ __u32 flags; =20 diff --git a/kernel/rseq.c b/kernel/rseq.c index dba44ca9f624..9355654e9b38 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -504,6 +504,26 @@ void rseq_delay_resched_tick(void) #endif } =20 +void rseq_delay_schedule(void) +{ +#ifdef CONFIG_SCHED_HRTICK + struct task_struct *t =3D current; + u32 flags; + + if (t->sched_time_delay) { + t->sched_time_delay =3D 0; + if (!t->rseq) + return; + if (copy_from_user_nofault(&flags, &t->rseq->flags, + sizeof(flags))) + return; + flags |=3D RSEQ_CS_FLAG_RESCHEDULED; + copy_to_user_nofault(&t->rseq->flags, &flags, + sizeof(flags)); + } +#endif +} + #ifdef CONFIG_DEBUG_RSEQ =20 /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8c8960245ec0..86583fb72914 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6734,8 +6734,7 @@ static void __sched notrace __schedule(int sched_mode) picked: clear_tsk_need_resched(prev); clear_preempt_need_resched(); - if (IS_ENABLED(CONFIG_RSEQ)) - prev->sched_time_delay =3D 0; + rseq_delay_schedule(); rq->last_seen_need_resched_ns =3D 0; =20 is_switch =3D prev !=3D next; --=20 2.43.5