3.10.32-rt31-rc2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior irq_work is processed in softirq context on -RT because we want to avoid long latencies which might arise from processing lots of perf events. The noHZ-full mode requires its callback to be called from real hardirq context (commit 76c24fb ("nohz: New APIs to re-evaluate the tick on full dynticks CPUs")). If it is called from a thread context we might get wrong results for checks like "is_idle_task(current)". This patch introduces a second list (hirq_work_list) which will be used if irq_work_run() has been invoked from hardirq context and process only work items marked with IRQ_WORK_HARD_IRQ. This patch also removes arch_irq_work_raise() from sparc & powerpc like it is already done for x86. Atleast for powerpc it is somehow superfluous because it is called from the timer interrupt which should invoke update_process_times(). Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt --- arch/powerpc/kernel/time.c | 2 +- arch/sparc/kernel/pcr.c | 2 ++ include/linux/irq_work.h | 1 + kernel/irq_work.c | 22 +++++++++++++++++++--- kernel/time/tick-sched.c | 1 + kernel/timer.c | 2 +- 6 files changed, 25 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 5fc29ad..7cc55b2 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -423,7 +423,7 @@ unsigned long profile_pc(struct pt_regs *regs) EXPORT_SYMBOL(profile_pc); #endif -#ifdef CONFIG_IRQ_WORK +#if defined(CONFIG_IRQ_WORK) && !defined(CONFIG_PREEMPT_RT_FULL) /* * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable... diff --git a/arch/sparc/kernel/pcr.c b/arch/sparc/kernel/pcr.c index 269af58..dbb51a6 100644 --- a/arch/sparc/kernel/pcr.c +++ b/arch/sparc/kernel/pcr.c @@ -43,10 +43,12 @@ void __irq_entry deferred_pcr_work_irq(int irq, struct pt_regs *regs) set_irq_regs(old_regs); } +#ifndef CONFIG_PREEMPT_RT_FULL void arch_irq_work_raise(void) { set_softint(1 << PIL_DEFERRED_PCR_WORK); } +#endif const struct pcr_ops *pcr_ops; EXPORT_SYMBOL_GPL(pcr_ops); diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index 6601702..60c19ee 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -16,6 +16,7 @@ #define IRQ_WORK_BUSY 2UL #define IRQ_WORK_FLAGS 3UL #define IRQ_WORK_LAZY 4UL /* Doesn't want IPI, wait for tick */ +#define IRQ_WORK_HARD_IRQ 8UL /* Run hard IRQ context, even on RT */ struct irq_work { unsigned long flags; diff --git a/kernel/irq_work.c b/kernel/irq_work.c index f6e4377..35d21f9 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -20,6 +20,9 @@ static DEFINE_PER_CPU(struct llist_head, irq_work_list); +#ifdef CONFIG_PREEMPT_RT_FULL +static DEFINE_PER_CPU(struct llist_head, hirq_work_list); +#endif static DEFINE_PER_CPU(int, irq_work_raised); /* @@ -48,7 +51,11 @@ static bool irq_work_claim(struct irq_work *work) return true; } +#ifdef CONFIG_PREEMPT_RT_FULL +void arch_irq_work_raise(void) +#else void __weak arch_irq_work_raise(void) +#endif { /* * Lame architectures will get the timer tick callback @@ -70,8 +77,12 @@ void irq_work_queue(struct irq_work *work) /* Queue the entry and raise the IPI if needed. */ preempt_disable(); - llist_add(&work->llnode, &__get_cpu_var(irq_work_list)); - +#ifdef CONFIG_PREEMPT_RT_FULL + if (work->flags & IRQ_WORK_HARD_IRQ) + llist_add(&work->llnode, &__get_cpu_var(hirq_work_list)); + else +#endif + llist_add(&work->llnode, &__get_cpu_var(irq_work_list)); /* * If the work is not "lazy" or the tick is stopped, raise the irq * work interrupt (if supported by the arch), otherwise, just wait @@ -115,7 +126,12 @@ static void __irq_work_run(void) __this_cpu_write(irq_work_raised, 0); barrier(); - this_list = &__get_cpu_var(irq_work_list); +#ifdef CONFIG_PREEMPT_RT_FULL + if (in_irq()) + this_list = &__get_cpu_var(hirq_work_list); + else +#endif + this_list = &__get_cpu_var(irq_work_list); if (llist_empty(this_list)) return; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 4e657e5..aa1e4b2 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -214,6 +214,7 @@ static void nohz_full_kick_work_func(struct irq_work *work) static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { .func = nohz_full_kick_work_func, + .flags = IRQ_WORK_HARD_IRQ, }; /* diff --git a/kernel/timer.c b/kernel/timer.c index f63a793..76846a1 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1425,7 +1425,7 @@ void update_process_times(int user_tick) scheduler_tick(); run_local_timers(); rcu_check_callbacks(cpu, user_tick); -#if defined(CONFIG_IRQ_WORK) && !defined(CONFIG_PREEMPT_RT_FULL) +#if defined(CONFIG_IRQ_WORK) if (in_irq()) irq_work_run(); #endif -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/