Re: [PATCH tip 1/1] trace: assign defaults at register_ftrace_event

[Ingo Molnar <mingo@elte.hu>]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Thu, Feb 05, 2009 at 02:24:30AM +0100, Ingo Molnar wrote:
> > 
> > * Arnaldo Carvalho de Melo <acme@redhat.com> wrote:
> > 
> > > Em Thu, Feb 05, 2009 at 12:41:51AM +0100, Frederic Weisbecker escreveu:
> > > > On Wed, Feb 04, 2009 at 08:16:39PM -0200, Arnaldo Carvalho de Melo wrote:
> > > > > Impact: simplification of tracers
> > > > > 
> > > > > As all tracers are doing this we might as well do it in
> > > > > register_ftrace_event and save one branch each time we call these
> > > > > callbacks.
> > > > > 
> > > > > Cc: Ingo Molnar <mingo@elte.hu>
> > > > > Cc: Frédéric Weisbecker <fweisbec@gmail.com>
> > > > > Cc: Jens Axboe <jens.axboe@oracle.com>
> > > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > > > ---
> > > > >  block/blktrace.c            |    2 --
> > > > >  kernel/trace/trace.c        |   13 +++++--------
> > > > >  kernel/trace/trace_branch.c |    3 ---
> > > > >  kernel/trace/trace_output.c |   13 +++++++++++--
> > > > >  4 files changed, 16 insertions(+), 15 deletions(-)
> > > > > 
> > > > > diff --git a/block/blktrace.c b/block/blktrace.c
> > > > > index c7698d1..1ebd068 100644
> > > > > --- a/block/blktrace.c
> > > > > +++ b/block/blktrace.c
> > > > > @@ -1243,8 +1243,6 @@ static struct trace_event trace_blk_event = {
> > > > >  	.type	 	= TRACE_BLK,
> > > > >  	.trace		= blk_trace_event_print,
> > > > >  	.latency_trace	= blk_trace_event_print,
> > > > > -	.raw		= trace_nop_print,
> > > > > -	.hex		= trace_nop_print,
> > > > >  	.binary		= blk_trace_event_print_binary,
> > > > >  };
> > > > >  
> > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > > > > index fd51cf0..a5e4c0a 100644
> > > > > --- a/kernel/trace/trace.c
> > > > > +++ b/kernel/trace/trace.c
> > > > > @@ -1412,7 +1412,7 @@ static enum print_line_t print_lat_fmt(struct trace_iterator *iter)
> > > > >  			goto partial;
> > > > >  	}
> > > > >  
> > > > > -	if (event && event->latency_trace)
> > > > > +	if (event)
> > > > >  		return event->latency_trace(iter, sym_flags);
> > > > >  
> > > > >  	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
> > > > > @@ -1441,7 +1441,7 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
> > > > >  			goto partial;
> > > > >  	}
> > > > >  
> > > > > -	if (event && event->trace)
> > > > > +	if (event)
> > > > >  		return event->trace(iter, sym_flags);
> > > > >  
> > > > >  	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
> > > > > @@ -1467,7 +1467,7 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
> > > > >  	}
> > > > >  
> > > > >  	event = ftrace_find_event(entry->type);
> > > > > -	if (event && event->raw)
> > > > > +	if (event)
> > > > >  		return event->raw(iter, 0);
> > > > >  
> > > > >  	if (!trace_seq_printf(s, "%d ?\n", entry->type))
> > > > > @@ -1494,7 +1494,7 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
> > > > >  	}
> > > > >  
> > > > >  	event = ftrace_find_event(entry->type);
> > > > > -	if (event && event->hex) {
> > > > > +	if (event) {
> > > > >  		enum print_line_t ret = event->hex(iter, 0);
> > > > >  		if (ret != TRACE_TYPE_HANDLED)
> > > > >  			return ret;
> > > > > @@ -1536,10 +1536,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
> > > > >  	}
> > > > >  
> > > > >  	event = ftrace_find_event(entry->type);
> > > > > -	if (event && event->binary)
> > > > > -		return event->binary(iter, 0);
> > > > > -
> > > > > -	return TRACE_TYPE_HANDLED;
> > > > > +	return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
> > > > >  }
> > > > >  
> > > > >  static int trace_empty(struct trace_iterator *iter)
> > > > > diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
> > > > > index 7ac72a4..297deb2 100644
> > > > > --- a/kernel/trace/trace_branch.c
> > > > > +++ b/kernel/trace/trace_branch.c
> > > > > @@ -182,9 +182,6 @@ static struct trace_event trace_branch_event = {
> > > > >  	.type	 	= TRACE_BRANCH,
> > > > >  	.trace		= trace_branch_print,
> > > > >  	.latency_trace	= trace_branch_print,
> > > > > -	.raw		= trace_nop_print,
> > > > > -	.hex		= trace_nop_print,
> > > > > -	.binary		= trace_nop_print,
> > > > >  };
> > > > >  
> > > > >  static struct tracer branch_trace __read_mostly =
> > > > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> > > > > index b7380ee..b6e99af 100644
> > > > > --- a/kernel/trace/trace_output.c
> > > > > +++ b/kernel/trace/trace_output.c
> > > > > @@ -435,6 +435,17 @@ int register_ftrace_event(struct trace_event *event)
> > > > >  	if (ftrace_find_event(event->type))
> > > > >  		goto out;
> > > > >  
> > > > > +	if (event->trace == NULL)
> > > > > +		event->trace = trace_nop_print;
> > > > > +	if (event->latency_trace == NULL)
> > > > > +		event->latency_trace = trace_nop_print;
> > > > > +	if (event->raw == NULL)
> > > > > +		event->raw = trace_nop_print;
> > > > > +	if (event->hex == NULL)
> > > > > +		event->hex = trace_nop_print;
> > > > > +	if (event->binary == NULL)
> > > > > +		event->binary = trace_nop_print;
> > > > > +
> > > > >  	key = event->type & (EVENT_HASHSIZE - 1);
> > > > >  
> > > > >  	hlist_add_head_rcu(&event->node, &event_hash[key]);
> > > > > @@ -874,8 +885,6 @@ static struct trace_event trace_print_event = {
> > > > >  	.trace		= trace_print_print,
> > > > >  	.latency_trace	= trace_print_print,
> > > > >  	.raw		= trace_print_raw,
> > > > > -	.hex		= trace_nop_print,
> > > > > -	.binary		= trace_nop_print,
> > > > >  };
> > > > >  
> > > > >  static struct trace_event *events[] __initdata = {
> > > > > -- 
> > > > > 1.6.0.6
> > > > > 
> > > > 
> > > > 
> > > > Nice! This avoids one branch for each entry printed.
> > > 
> > > Is that an Acked-by in response to that CC? :-)
> > 
> > yes, i generally treat such replies as an implicit Acked-by and add them - 
> > already added Fredric's acks to two other commits of yours earlier today. An 
> > explicit Acked-by is even more helpful though :-)
> > 
> > 	Ingo
> 
> 
> Heh, I'm not a tracing/core/ftrace maintainer, so I wouldn't dare put my 
> Acked-by unless it touches a file I started :-) Concerning 
> tracing/core/ftrace/tracers, I review the patches that come if I have the 
> time to and tell what I think about it. But in my opinion, the Acked-by on 
> this area are more appropriate if they come from Steven :-)

if you read a patch, in an area of code that you know well (which you do in 
this case), and if you find the patch it a step forward with no defects then 
feel free to post an Acked-by.

You absolutely dont have to be the primary author of a file to do that. All 
such help makes maintenance easier and is much appreciated.

	Ingo