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    Subject[PATCH 1/4 v2] init, tracing: Add initcall trace events
    From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

    Being able to trace the start and stop of initcalls is useful to see where
    the timings are an issue. There is already an "initcall_debug" parameter,
    but that can cause a large overhead itself, as the printing of the
    information may take longer than the initcall functions.

    Adding in a start and finish trace event around the initcall functions, as
    well as a trace event that records the level of the initcalls, one can get a
    much finer measurement of the times and interactions of the initcalls
    themselves, as trace events are much lighter than printk()s.

    Suggested-by: Abderrahmane Benbachir <abderrahmane.benbachir@polymtl.ca>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    ---
    include/trace/events/initcall.h | 66 +++++++++++++++++++++++++++++++++++++++++
    init/main.c | 7 +++++
    2 files changed, 73 insertions(+)
    create mode 100644 include/trace/events/initcall.h

    diff --git a/include/trace/events/initcall.h b/include/trace/events/initcall.h
    new file mode 100644
    index 000000000000..8d6cf10d27c9
    --- /dev/null
    +++ b/include/trace/events/initcall.h
    @@ -0,0 +1,66 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +#undef TRACE_SYSTEM
    +#define TRACE_SYSTEM initcall
    +
    +#if !defined(_TRACE_INITCALL_H) || defined(TRACE_HEADER_MULTI_READ)
    +#define _TRACE_INITCALL_H
    +
    +#include <linux/tracepoint.h>
    +
    +TRACE_EVENT(initcall_level,
    +
    + TP_PROTO(const char *level),
    +
    + TP_ARGS(level),
    +
    + TP_STRUCT__entry(
    + __string(level, level)
    + ),
    +
    + TP_fast_assign(
    + __assign_str(level, level);
    + ),
    +
    + TP_printk("level=%s", __get_str(level))
    +);
    +
    +TRACE_EVENT(initcall_start,
    +
    + TP_PROTO(initcall_t func),
    +
    + TP_ARGS(func),
    +
    + TP_STRUCT__entry(
    + __field(initcall_t, func)
    + ),
    +
    + TP_fast_assign(
    + __entry->func = func;
    + ),
    +
    + TP_printk("func=%pS", __entry->func)
    +);
    +
    +TRACE_EVENT(initcall_finish,
    +
    + TP_PROTO(initcall_t func, int ret),
    +
    + TP_ARGS(func, ret),
    +
    + TP_STRUCT__entry(
    + __field(initcall_t, func)
    + __field(int, ret)
    + ),
    +
    + TP_fast_assign(
    + __entry->func = func;
    + __entry->ret = ret;
    + ),
    +
    + TP_printk("func=%pS ret=%d", __entry->func, __entry->ret)
    +);
    +
    +#endif /* if !defined(_TRACE_GPIO_H) || defined(TRACE_HEADER_MULTI_READ) */
    +
    +/* This part must be outside protection */
    +#include <trace/define_trace.h>
    diff --git a/init/main.c b/init/main.c
    index 0ebdd5f15be8..2af8f2bb5ca8 100644
    --- a/init/main.c
    +++ b/init/main.c
    @@ -97,6 +97,9 @@
    #include <asm/sections.h>
    #include <asm/cacheflush.h>

    +#define CREATE_TRACE_POINTS
    +#include <trace/events/initcall.h>
    +
    static int kernel_init(void *);

    extern void init_IRQ(void);
    @@ -827,10 +830,12 @@ int __init_or_module do_one_initcall(initcall_t fn)
    if (initcall_blacklisted(fn))
    return -EPERM;

    + trace_initcall_start(fn);
    if (initcall_debug)
    ret = do_one_initcall_debug(fn);
    else
    ret = fn();
    + trace_initcall_finish(fn, ret);

    msgbuf[0] = 0;

    @@ -895,6 +900,7 @@ static void __init do_initcall_level(int level)
    level, level,
    NULL, &repair_env_string);

    + trace_initcall_level(initcall_level_names[level]);
    for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
    do_one_initcall(*fn);
    }
    @@ -929,6 +935,7 @@ static void __init do_pre_smp_initcalls(void)
    {
    initcall_t *fn;

    + trace_initcall_level("early");
    for (fn = __initcall_start; fn < __initcall0_start; fn++)
    do_one_initcall(*fn);
    }
    --
    2.15.1

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