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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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