Commit cf8e3474 authored Mar 30, 2009 by Lai Jiangshan Committed by Ingo Molnar Apr 07, 2009

tracing: fix incorrect return type of ns2usecs()



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.

Changes in v2:
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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 301fd748

kernel/trace/trace.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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);

kernel/trace/trace.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -596,7 +596,7 @@ 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

kernel/trace/trace_output.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -423,7 +423,7 @@ 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,

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