On Thu, Sep 03, 2020 at 05:36:49PM +0200, [email protected] wrote:
> On Thu, Sep 03, 2020 at 08:19:38AM -0700, Guenter Roeck wrote:
> > This doesn't compile for me - there is no "name" parameter in __DO_TRACE().
> >
> > Error log:
> > In file included from ./include/linux/rculist.h:11,
> > from ./include/linux/pid.h:5,
> > from ./include/linux/sched.h:14,
> > from ./include/linux/sched/numa_balancing.h:10,
> > from ./include/trace/events/sched.h:8,
> > from kernel/sched/core.c:10:
> > ./include/trace/events/sched.h: In function 'trace_sched_kthread_stop':
> > ./include/linux/tracepoint.h:175:26: error: '__tracepoint_name' undeclared
> >
> > I applied your patch on top of v5.9-rc3-75-gfc3abb53250a. Are you using
> > a different branch ?
>
> Argh, I was on tip/master... easy fix though.
>
> ---
> diff --git a/include/linux/preempt.h b/include/linux/preempt.h
> index 7d9c1c0e149c..878bac893e41 100644
> --- a/include/linux/preempt.h
> +++ b/include/linux/preempt.h
> @@ -27,17 +27,20 @@
> * SOFTIRQ_MASK: 0x0000ff00
> * HARDIRQ_MASK: 0x000f0000
> * NMI_MASK: 0x00f00000
> + * RCUIDLE_MASK: 0x01000000
> * PREEMPT_NEED_RESCHED: 0x80000000
> */
> #define PREEMPT_BITS 8
> #define SOFTIRQ_BITS 8
> #define HARDIRQ_BITS 4
> #define NMI_BITS 4
> +#define RCUIDLE_BITS 1
>
> #define PREEMPT_SHIFT 0
> #define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
> #define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
> #define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS)
> +#define RCUIDLE_SHIFT (NMI_SHIFT + NMI_BITS)
>
> #define __IRQ_MASK(x) ((1UL << (x))-1)
>
> @@ -45,11 +48,13 @@
> #define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
> #define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
> #define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT)
> +#define RCUIDLE_MASK (__IRQ_MASK(RCUIDLE_BITS) << RCUIDLE_SHIFT)
>
> #define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
> #define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
> #define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
> #define NMI_OFFSET (1UL << NMI_SHIFT)
> +#define RCUIDLE_OFFSET (1UL << RCUIDLE_SHIFT)
>
> #define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
>
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 598fec9f9dbf..0469bc1c24fc 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -164,12 +164,18 @@ static inline struct tracepoint
> *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> void *__data; \
> int __maybe_unused __idx = 0; \
> \
> - if (!(cond)) \
> + if (!(cond) || (preempt_count() & RCUIDLE_MASK)) \
> return; \
> \
> /* srcu can't be used from NMI */ \
> WARN_ON_ONCE(rcuidle && in_nmi()); \
> \
> + if (IS_ENABLED(CONFIG_LOCKDEP) && !(rcuidle)) { \
> + rcu_read_lock_sched_notrace(); \
> + rcu_dereference_sched((tp)->funcs); \
> + rcu_read_unlock_sched_notrace(); \
> + } \
> + \
> /* keep srcu and sched-rcu usage consistent */ \
> preempt_disable_notrace(); \
> \
> @@ -235,11 +241,6 @@ static inline struct tracepoint
> *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> TP_PROTO(data_proto), \
> TP_ARGS(data_args), \
> TP_CONDITION(cond), 0); \
> - if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
> - rcu_read_lock_sched_notrace(); \
> - rcu_dereference_sched(__tracepoint_##name.funcs);\
> - rcu_read_unlock_sched_notrace(); \
> - } \
> } \
> __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
> PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 8ce77d9ac716..ad9fb4f12c63 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -269,6 +269,8 @@ static noinstr void rcu_dynticks_eqs_enter(void)
> /* Better not have special action (TLB flush) pending! */
> WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
> (seq & RCU_DYNTICK_CTRL_MASK));
> +
> + __preempt_count_add(RCUIDLE_OFFSET);
But the rcu_data structure's ->dynticks field is still to be used in cases
where the RCU grace-period kthread must do off-CPU access to the CPU's
RCU-idle state, correct? (Otherwise, some memory barriers are needed.)
Thanx, Paul
> }
>
> /*
> @@ -281,6 +283,8 @@ static noinstr void rcu_dynticks_eqs_exit(void)
> struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
> int seq;
>
> + __preempt_count_sub(RCUIDLE_OFFSET);
> +
> /*
> * CPUs seeing atomic_add_return() must see prior idle sojourns,
> * and we also must force ordering with the next RCU read-side
>
>
