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    SubjectRe: [PATCH v4 1/5] irq: add tracepoint to softirq_raise
    On Mon, Aug 23, 2010 at 06:42:48PM +0900, Koki Sanagi wrote:
    > From: Lai Jiangshan <laijs@cn.fujitsu.com>
    >
    > Add a tracepoint for tracing when softirq action is raised.
    >
    > It and the existed tracepoints complete softirq's tracepoints:
    > softirq_raise, softirq_entry and softirq_exit.
    >
    > And when this tracepoint is used in combination with
    > the softirq_entry tracepoint we can determine
    > the softirq raise latency.
    >
    > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
    > Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    > Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
    >
    > [ factorize softirq events with DECLARE_EVENT_CLASS ]
    > Signed-off-by: Koki Sanagi <sanagi.koki@jp.fujitsu.com>
    > ---
    > include/linux/interrupt.h | 8 +++++++-
    > include/trace/events/irq.h | 26 ++++++++++++++++++++++++--
    > 2 files changed, 31 insertions(+), 3 deletions(-)
    >
    > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
    > index a0384a4..d3e8e90 100644
    > --- a/include/linux/interrupt.h
    > +++ b/include/linux/interrupt.h
    > @@ -18,6 +18,7 @@
    > #include <asm/atomic.h>
    > #include <asm/ptrace.h>
    > #include <asm/system.h>
    > +#include <trace/events/irq.h>
    >
    > /*
    > * These correspond to the IORESOURCE_IRQ_* defines in
    > @@ -407,7 +408,12 @@ asmlinkage void do_softirq(void);
    > asmlinkage void __do_softirq(void);
    > extern void open_softirq(int nr, void (*action)(struct softirq_action *));
    > extern void softirq_init(void);
    > -#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
    > +static inline void __raise_softirq_irqoff(unsigned int nr)
    > +{
    > + trace_softirq_raise((struct softirq_action *)&nr, NULL);
    > + or_softirq_pending(1UL << nr);
    > +}
    > +
    > extern void raise_softirq_irqoff(unsigned int nr);
    > extern void raise_softirq(unsigned int nr);
    > extern void wakeup_softirqd(void);
    > diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
    > index 0e4cfb6..3ddda02 100644
    > --- a/include/trace/events/irq.h
    > +++ b/include/trace/events/irq.h
    > @@ -5,7 +5,9 @@
    > #define _TRACE_IRQ_H
    >
    > #include <linux/tracepoint.h>
    > -#include <linux/interrupt.h>
    > +
    > +struct irqaction;
    > +struct softirq_action;
    >
    > #define softirq_name(sirq) { sirq##_SOFTIRQ, #sirq }
    > #define show_softirq_name(val) \
    > @@ -93,7 +95,10 @@ DECLARE_EVENT_CLASS(softirq,
    > ),
    >
    > TP_fast_assign(
    > - __entry->vec = (int)(h - vec);
    > + if (vec)
    > + __entry->vec = (int)(h - vec);
    > + else
    > + __entry->vec = *((int *)h);
    > ),



    It seems that this will break softirq_entry/exit tracepoints.
    __entry->vec will deref vec->action() for these two, which is not
    what we want.

    If you can't have the same tracepoint signature for the three, just
    split the new one in a seperate TRACE_EVENT().

    Thanks.



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