rostedt at goodmis
Aug 8, 2013, 9:12 AM
Post #2 of 3
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Re: [for-next-3.11][PATCH 4/4] tracing: Fix reset of time stamps during trace_clock changes
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Greg,
I'm testing the backports, and I found that this patch depends on commit
10246fa35d4ffdfe472185d4cbf9c2dfd9a9f023 "tracing: Use flag
buffer_disabled for irqsoff tracer"
Please add that to 3.10 before applying this fix.
Thanks!
-- Steve
On Sat, 2013-08-03 at 08:49 -0400, Steven Rostedt wrote:
> plain text document attachment
> (0004-tracing-Fix-reset-of-time-stamps-during-trace_clock-.patch)
> From: Alexander Z Lam <azl [at] google>
>
> Fixed two issues with changing the timestamp clock with trace_clock:
>
> - The global buffer was reset on instance clock changes. Change this to pass
> the correct per-instance buffer
> - ftrace_now() is used to set buf->time_start in tracing_reset_online_cpus().
> This was incorrect because ftrace_now() used the global buffer's clock to
> return the current time. Change this to use buffer_ftrace_now() which
> returns the current time for the correct per-instance buffer.
>
> Also removed tracing_reset_current() because it is not used anywhere
>
> Link: http://lkml.kernel.org/r/1375493777-17261-2-git-send-email-azl [at] google
>
> Cc: Vaibhav Nagarnaik <vnagarnaik [at] google>
> Cc: David Sharp <dhsharp [at] google>
> Cc: Alexander Z Lam <lambchop468 [at] gmail>
> Cc: stable [at] vger # 3.10
> Signed-off-by: Alexander Z Lam <azl [at] google>
> Signed-off-by: Steven Rostedt <rostedt [at] goodmis>
> ---
> kernel/trace/trace.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 531c9e6..496f94d 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -243,20 +243,25 @@ int filter_current_check_discard(struct ring_buffer *buffer,
> }
> EXPORT_SYMBOL_GPL(filter_current_check_discard);
>
> -cycle_t ftrace_now(int cpu)
> +cycle_t buffer_ftrace_now(struct trace_buffer *buf, int cpu)
> {
> u64 ts;
>
> /* Early boot up does not have a buffer yet */
> - if (!global_trace.trace_buffer.buffer)
> + if (!buf->buffer)
> return trace_clock_local();
>
> - ts = ring_buffer_time_stamp(global_trace.trace_buffer.buffer, cpu);
> - ring_buffer_normalize_time_stamp(global_trace.trace_buffer.buffer, cpu, &ts);
> + ts = ring_buffer_time_stamp(buf->buffer, cpu);
> + ring_buffer_normalize_time_stamp(buf->buffer, cpu, &ts);
>
> return ts;
> }
>
> +cycle_t ftrace_now(int cpu)
> +{
> + return buffer_ftrace_now(&global_trace.trace_buffer, cpu);
> +}
> +
> /**
> * tracing_is_enabled - Show if global_trace has been disabled
> *
> @@ -1211,7 +1216,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf)
> /* Make sure all commits have finished */
> synchronize_sched();
>
> - buf->time_start = ftrace_now(buf->cpu);
> + buf->time_start = buffer_ftrace_now(buf, buf->cpu);
>
> for_each_online_cpu(cpu)
> ring_buffer_reset_cpu(buffer, cpu);
> @@ -1219,11 +1224,6 @@ void tracing_reset_online_cpus(struct trace_buffer *buf)
> ring_buffer_record_enable(buffer);
> }
>
> -void tracing_reset_current(int cpu)
> -{
> - tracing_reset(&global_trace.trace_buffer, cpu);
> -}
> -
> /* Must have trace_types_lock held */
> void tracing_reset_all_online_cpus(void)
> {
> @@ -4634,12 +4634,12 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
> * New clock may not be consistent with the previous clock.
> * Reset the buffer so that it doesn't have incomparable timestamps.
> */
> - tracing_reset_online_cpus(&global_trace.trace_buffer);
> + tracing_reset_online_cpus(&tr->trace_buffer);
>
> #ifdef CONFIG_TRACER_MAX_TRACE
> if (tr->flags & TRACE_ARRAY_FL_GLOBAL && tr->max_buffer.buffer)
> ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);
> - tracing_reset_online_cpus(&global_trace.max_buffer);
> + tracing_reset_online_cpus(&tr->max_buffer);
> #endif
>
> mutex_unlock(&trace_types_lock);
--
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