The vtime seqlock needs to be taken in true interrupt context on -rt. The normal seqlocks are converted to mutexes when PREEMPT_RT_FULL is enabled, which will break the vtime code as the calls are done from interrupt context.
Convert the vtime seqlock into the raw_spinlock_t and seqcount combo that can be done in interrupt context. Signed-off-by: Steven Rostedt <[email protected]> Index: linux-rt.git/include/linux/sched.h =================================================================== --- linux-rt.git.orig/include/linux/sched.h +++ linux-rt.git/include/linux/sched.h @@ -1176,7 +1176,8 @@ struct task_struct { struct cputime prev_cputime; #endif #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN - seqlock_t vtime_seqlock; + raw_spinlock_t vtime_lock; + seqcount_t vtime_seq; unsigned long long vtime_snap; enum { VTIME_SLEEPING = 0, Index: linux-rt.git/kernel/sched/cputime.c =================================================================== --- linux-rt.git.orig/kernel/sched/cputime.c +++ linux-rt.git/kernel/sched/cputime.c @@ -668,9 +668,11 @@ void vtime_account_system(struct task_st if (!vtime_accounting_enabled()) return; - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); __vtime_account_system(tsk); - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_account_irq_exit(struct task_struct *tsk) @@ -678,11 +680,13 @@ void vtime_account_irq_exit(struct task_ if (!vtime_accounting_enabled()) return; - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); if (context_tracking_in_user()) tsk->vtime_snap_whence = VTIME_USER; __vtime_account_system(tsk); - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_account_user(struct task_struct *tsk) @@ -694,10 +698,12 @@ void vtime_account_user(struct task_stru delta_cpu = get_vtime_delta(tsk); - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); tsk->vtime_snap_whence = VTIME_SYS; account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu)); - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_user_enter(struct task_struct *tsk) @@ -705,26 +711,32 @@ void vtime_user_enter(struct task_struct if (!vtime_accounting_enabled()) return; - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); tsk->vtime_snap_whence = VTIME_USER; __vtime_account_system(tsk); - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_guest_enter(struct task_struct *tsk) { - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); __vtime_account_system(tsk); current->flags |= PF_VCPU; - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_guest_exit(struct task_struct *tsk) { - write_seqlock(&tsk->vtime_seqlock); + raw_spin_lock(&tsk->vtime_lock); + write_seqcount_begin(&tsk->vtime_seq); __vtime_account_system(tsk); current->flags &= ~PF_VCPU; - write_sequnlock(&tsk->vtime_seqlock); + write_seqcount_end(&tsk->vtime_seq); + raw_spin_unlock(&tsk->vtime_lock); } void vtime_account_idle(struct task_struct *tsk) @@ -741,24 +753,30 @@ bool vtime_accounting_enabled(void) void arch_vtime_task_switch(struct task_struct *prev) { - write_seqlock(&prev->vtime_seqlock); + raw_spin_lock(&prev->vtime_lock); + write_seqcount_begin(&prev->vtime_seq); prev->vtime_snap_whence = VTIME_SLEEPING; - write_sequnlock(&prev->vtime_seqlock); + write_seqcount_end(&prev->vtime_seq); + raw_spin_unlock(&prev->vtime_lock); - write_seqlock(¤t->vtime_seqlock); + raw_spin_lock(¤t->vtime_lock); + write_seqcount_begin(¤t->vtime_seq); current->vtime_snap_whence = VTIME_SYS; current->vtime_snap = sched_clock_cpu(smp_processor_id()); - write_sequnlock(¤t->vtime_seqlock); + write_seqcount_end(¤t->vtime_seq); + raw_spin_unlock(¤t->vtime_lock); } void vtime_init_idle(struct task_struct *t, int cpu) { unsigned long flags; - write_seqlock_irqsave(&t->vtime_seqlock, flags); + raw_spin_lock_irqsave(&t->vtime_lock, flags); + write_seqcount_begin(&t->vtime_seq); t->vtime_snap_whence = VTIME_SYS; t->vtime_snap = sched_clock_cpu(cpu); - write_sequnlock_irqrestore(&t->vtime_seqlock, flags); + write_seqcount_end(&t->vtime_seq); + raw_spin_unlock_irqrestore(&t->vtime_lock, flags); } cputime_t task_gtime(struct task_struct *t) @@ -767,13 +785,13 @@ cputime_t task_gtime(struct task_struct cputime_t gtime; do { - seq = read_seqbegin(&t->vtime_seqlock); + seq = read_seqcount_begin(&t->vtime_seq); gtime = t->gtime; if (t->flags & PF_VCPU) gtime += vtime_delta(t); - } while (read_seqretry(&t->vtime_seqlock, seq)); + } while (read_seqcount_retry(&t->vtime_seq, seq)); return gtime; } @@ -796,7 +814,7 @@ fetch_task_cputime(struct task_struct *t *udelta = 0; *sdelta = 0; - seq = read_seqbegin(&t->vtime_seqlock); + seq = read_seqcount_begin(&t->vtime_seq); if (u_dst) *u_dst = *u_src; @@ -820,7 +838,7 @@ fetch_task_cputime(struct task_struct *t if (t->vtime_snap_whence == VTIME_SYS) *sdelta = delta; } - } while (read_seqretry(&t->vtime_seqlock, seq)); + } while (read_seqcount_retry(&t->vtime_seq, seq)); } Index: linux-rt.git/include/linux/init_task.h =================================================================== --- linux-rt.git.orig/include/linux/init_task.h +++ linux-rt.git/include/linux/init_task.h @@ -151,7 +151,8 @@ extern struct task_group root_task_group #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN # define INIT_VTIME(tsk) \ - .vtime_seqlock = __SEQLOCK_UNLOCKED(tsk.vtime_seqlock), \ + .vtime_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.vtime_lock), \ + .vtime_seq = SEQCNT_ZERO, \ .vtime_snap = 0, \ .vtime_snap_whence = VTIME_SYS, #else Index: linux-rt.git/kernel/fork.c =================================================================== --- linux-rt.git.orig/kernel/fork.c +++ linux-rt.git/kernel/fork.c @@ -1268,7 +1268,8 @@ static struct task_struct *copy_process( p->prev_cputime.utime = p->prev_cputime.stime = 0; #endif #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN - seqlock_init(&p->vtime_seqlock); + raw_spin_lock_init(&p->vtime_lock); + seqcount_init(&p->vtime_seq); p->vtime_snap = 0; p->vtime_snap_whence = VTIME_SLEEPING; #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
