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Date: Fri, 14 Nov 2014 13:41:26 +0100
From: Petr Mladek <pmladek@...e.cz>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Jiri Kosina <jkosina@...e.cz>
Subject: Re: [RFC][PATCH 06/23 v4] tracing: Have function_graph use
trace_seq_has_overflowed()
On Thu 2014-11-13 20:12:50, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
>
> Instead of doing individual checks all over the place that makes the code
> very messy. Just check trace_seq_has_overflowed() at the end or in
> strategic places.
>
> This makes the code much cleaner and also helps with getting closer
> to removing the return values of trace_seq_printf() and friends.
>
> Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
> ---
> kernel/trace/trace.h | 2 +-
> kernel/trace/trace_functions_graph.c | 374 +++++++++++------------------------
> 2 files changed, 116 insertions(+), 260 deletions(-)
>
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 19418221b302..c3a37e55ec8b 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -726,7 +726,7 @@ extern unsigned long trace_flags;
> extern enum print_line_t
> print_graph_function_flags(struct trace_iterator *iter, u32 flags);
> extern void print_graph_headers_flags(struct seq_file *s, u32 flags);
> -extern enum print_line_t
> +extern void
> trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
> extern void graph_trace_open(struct trace_iterator *iter);
> extern void graph_trace_close(struct trace_iterator *iter);
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index f0a0c982cde3..477a7c65cf08 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
[...]
> @@ -682,94 +639,69 @@ get_return_for_leaf(struct trace_iterator *iter,
> return next;
> }
>
> -static int print_graph_abs_time(u64 t, struct trace_seq *s)
> +static void print_graph_abs_time(u64 t, struct trace_seq *s)
> {
> unsigned long usecs_rem;
>
> usecs_rem = do_div(t, NSEC_PER_SEC);
> usecs_rem /= 1000;
>
> - return trace_seq_printf(s, "%5lu.%06lu | ",
> - (unsigned long)t, usecs_rem);
> + trace_seq_printf(s, "%5lu.%06lu | ",
> + (unsigned long)t, usecs_rem);
> }
>
> -static enum print_line_t
> +static void
> print_graph_irq(struct trace_iterator *iter, unsigned long addr,
> enum trace_type type, int cpu, pid_t pid, u32 flags)
> {
> - int ret;
> struct trace_seq *s = &iter->seq;
>
> if (addr < (unsigned long)__irqentry_text_start ||
> addr >= (unsigned long)__irqentry_text_end)
> - return TRACE_TYPE_UNHANDLED;
> + return;
I was curious if the TRACE_TYPE_UNHANDLED return value has any special
effect. But it seems to be ignored. There are only two callers and
they take care only of the PARTIAL_LINE return value.
[...]
> @@ -953,62 +856,43 @@ print_graph_entry_nested(struct trace_iterator *iter,
> return TRACE_TYPE_NO_CONSUME;
> }
>
> -static enum print_line_t
> +static void
> print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
> int type, unsigned long addr, u32 flags)
> {
> struct fgraph_data *data = iter->private;
> struct trace_entry *ent = iter->ent;
> int cpu = iter->cpu;
> - int ret;
>
> /* Pid */
> - if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
> - return TRACE_TYPE_PARTIAL_LINE;
> + verif_pid(s, ent->pid, cpu, data);
>
> - if (type) {
> + if (type)
> /* Interrupt */
> - ret = print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
> - if (ret == TRACE_TYPE_PARTIAL_LINE)
> - return TRACE_TYPE_PARTIAL_LINE;
> - }
> + print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
>
> if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
> - return 0;
> + return;
>
> /* Absolute time */
> - if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
> - ret = print_graph_abs_time(iter->ts, s);
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> - }
> + if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
> + print_graph_abs_time(iter->ts, s);
>
> /* Cpu */
> - if (flags & TRACE_GRAPH_PRINT_CPU) {
> - ret = print_graph_cpu(s, cpu);
> - if (ret == TRACE_TYPE_PARTIAL_LINE)
> - return TRACE_TYPE_PARTIAL_LINE;
> - }
> + if (flags & TRACE_GRAPH_PRINT_CPU)
> + print_graph_cpu(s, cpu);
>
> /* Proc */
> if (flags & TRACE_GRAPH_PRINT_PROC) {
> - ret = print_graph_proc(s, ent->pid);
> - if (ret == TRACE_TYPE_PARTIAL_LINE)
> - return TRACE_TYPE_PARTIAL_LINE;
> -
> - ret = trace_seq_puts(s, " | ");
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> + print_graph_proc(s, ent->pid);
> + trace_seq_puts(s, " | ");
> }
>
> /* Latency format */
> - if (trace_flags & TRACE_ITER_LATENCY_FMT) {
> - ret = print_graph_lat_fmt(s, ent);
> - if (ret == TRACE_TYPE_PARTIAL_LINE)
> - return TRACE_TYPE_PARTIAL_LINE;
> - }
> + if (trace_flags & TRACE_ITER_LATENCY_FMT)
> + print_graph_lat_fmt(s, ent);
>
> - return 0;
> + return;
This probably even fixed a bug. The function returned
TRACE_TYPE_PARTIAL_LINE (0) even when it did not print anything.
The simplification is really cool.
Reviewed-by: Petr Mladek <pmladek@...e.cz>
Best Regards,
Petr Mladek
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