From: Sebastian Andrzej Siewior Date: Wed, 20 Jan 2016 15:39:05 +0100 Subject: [PATCH 199/342] net: provide a way to delegate processing a softirq to ksoftirqd Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=9c6bc0e0c15e8990049af42ea7f423c9057c262d If the NET_RX uses up all of his budget it moves the following NAPI invocations into the `ksoftirqd`. On -RT it does not do so. Instead it rises the NET_RX softirq in its current context again. In order to get closer to mainline's behaviour this patch provides __raise_softirq_irqoff_ksoft() which raises the softirq in the ksoftird. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- include/linux/interrupt.h | 8 ++++++++ kernel/softirq.c | 21 +++++++++++++++++++++ net/core/dev.c | 2 +- 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index e1438fe66467..97d9ba26915e 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -518,6 +518,14 @@ extern void thread_do_softirq(void); extern void open_softirq(int nr, void (*action)(struct softirq_action *)); extern void softirq_init(void); extern void __raise_softirq_irqoff(unsigned int nr); +#ifdef CONFIG_PREEMPT_RT_FULL +extern void __raise_softirq_irqoff_ksoft(unsigned int nr); +#else +static inline void __raise_softirq_irqoff_ksoft(unsigned int nr) +{ + __raise_softirq_irqoff(nr); +} +#endif extern void raise_softirq_irqoff(unsigned int nr); extern void raise_softirq(unsigned int nr); diff --git a/kernel/softirq.c b/kernel/softirq.c index 27a4bb2303d0..25bcf2f2714b 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -721,6 +721,27 @@ void __raise_softirq_irqoff(unsigned int nr) wakeup_proper_softirq(nr); } +/* + * Same as __raise_softirq_irqoff() but will process them in ksoftirqd + */ +void __raise_softirq_irqoff_ksoft(unsigned int nr) +{ + unsigned int mask; + + if (WARN_ON_ONCE(!__this_cpu_read(ksoftirqd) || + !__this_cpu_read(ktimer_softirqd))) + return; + mask = 1UL << nr; + + trace_softirq_raise(nr); + or_softirq_pending(mask); + if (mask & TIMER_SOFTIRQS) + __this_cpu_read(ktimer_softirqd)->softirqs_raised |= mask; + else + __this_cpu_read(ksoftirqd)->softirqs_raised |= mask; + wakeup_proper_softirq(nr); +} + /* * This function must run with irqs disabled! */ diff --git a/net/core/dev.c b/net/core/dev.c index a59b1db02f8b..2bf357d5602b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6391,7 +6391,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h) list_splice_tail(&repoll, &list); list_splice(&list, &sd->poll_list); if (!list_empty(&sd->poll_list)) - __raise_softirq_irqoff(NET_RX_SOFTIRQ); + __raise_softirq_irqoff_ksoft(NET_RX_SOFTIRQ); net_rps_action_and_irq_enable(sd); out: