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    Subject[PATCH 03/10] tracing: fix incorrect return type of ns2usecs() V2
    From: Lai Jiangshan <laijs@cn.fujitsu.com>

    Impact: fix time output bug in 32bits system

    ns2usecs() returns 'long', it's incorrect.

    (In i386)
    ...
    <idle>-0 [000] 521.442100: _spin_lock <-tick_do_update_jiffies64
    <idle>-0 [000] 521.442101: do_timer <-tick_do_update_jiffies64
    <idle>-0 [000] 521.442102: update_wall_time <-do_timer
    <idle>-0 [000] 521.442102: update_xtime_cache <-update_wall_time
    ....
    (It always print the time less than 2200 seconds besides ...)
    Because 'long' is 32bits in i386. ( (1<<31) useconds is about 2200 seconds)

    ...
    <idle>-0 [001] 4154502640.134759: rcu_bh_qsctr_inc <-__do_softirq
    <idle>-0 [001] 4154502640.134760: _local_bh_enable <-__do_softirq
    <idle>-0 [001] 4154502640.134761: idle_cpu <-irq_exit
    ...
    (very large value)
    Because 'long' is a signed type and it is 32bits in i386.

    Changed from V1:
    return 'unsigned long long' instead of 'cycle_t'

    Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
    LKML-Reference: <49D05D10.4030009@cn.fujitsu.com>
    Reported-by: Li Zefan <lizf@cn.fujitsu.com>
    Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
    ---
    kernel/trace/trace.c | 3 +--
    kernel/trace/trace.h | 2 +-
    kernel/trace/trace_output.c | 2 +-
    3 files changed, 3 insertions(+), 4 deletions(-)

    diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
    index 2a81dec..5232201 100644
    --- a/kernel/trace/trace.c
    +++ b/kernel/trace/trace.c
    @@ -147,8 +147,7 @@ static int __init set_ftrace_dump_on_oops(char *str)
    }
    __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);

    -long
    -ns2usecs(cycle_t nsec)
    +unsigned long long ns2usecs(cycle_t nsec)
    {
    nsec += 500;
    do_div(nsec, 1000);
    diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
    index fec6521..47aa6d0 100644
    --- a/kernel/trace/trace.h
    +++ b/kernel/trace/trace.h
    @@ -602,7 +602,7 @@ extern int trace_selftest_startup_branch(struct tracer *trace,
    #endif /* CONFIG_FTRACE_STARTUP_TEST */

    extern void *head_page(struct trace_array_cpu *data);
    -extern long ns2usecs(cycle_t nsec);
    +extern unsigned long long ns2usecs(cycle_t nsec);
    extern int
    trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
    extern int
    diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
    index aeac358..0e70fb0 100644
    --- a/kernel/trace/trace_output.c
    +++ b/kernel/trace/trace_output.c
    @@ -433,7 +433,7 @@ int trace_print_lat_context(struct trace_iterator *iter)

    trace_find_cmdline(entry->pid, comm);

    - ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08lx]"
    + ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08llx]"
    " %ld.%03ldms (+%ld.%03ldms): ", comm,
    entry->pid, iter->cpu, entry->flags,
    entry->preempt_count, iter->idx,
    --
    1.6.2.1
    --


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