tracing: Remove spurious default precision from show_event_trigger/filter formats

[PATCH next] tracing: Remove spurious default precision from show_event_trigger/filter formats

Posted by david.laight.linux@gmail.com 6 days, 20 hours ago

From: David Laight <david.laight.linux@gmail.com>

Change 2d8b7f9bf8e6e ("tracing: Have show_event_trigger/filter format a bit more in columns")
added space padding to align the output.
However it used ("%*.s", len, "") which requests the default precision.
It doesn't matter here whether the userspace default (0) or kernel
default (no precision) is used, but the format should be "%*s".

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 kernel/trace/trace_events.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 249d1cba72c0..6b54c10f9ba4 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1718,7 +1718,7 @@ static int t_show_filters(struct seq_file *m, void *v)
 
 	len = get_call_len(call);
 
-	seq_printf(m, "%s:%s%*.s%s\n", call->class->system,
+	seq_printf(m, "%s:%s%*s%s\n", call->class->system,
 		   trace_event_name(call), len, "", filter->filter_string);
 
 	return 0;
@@ -1750,7 +1750,7 @@ static int t_show_triggers(struct seq_file *m, void *v)
 	len = get_call_len(call);
 
 	list_for_each_entry_rcu(data, &file->triggers, list) {
-		seq_printf(m, "%s:%s%*.s", call->class->system,
+		seq_printf(m, "%s:%s%*s", call->class->system,
 			   trace_event_name(call), len, "");
 
 		data->cmd_ops->print(m, data);
-- 
2.39.5

Re: [PATCH next] tracing: Remove spurious default precision from show_event_trigger/filter formats

Posted by Aaron Tomlin 6 days, 3 hours ago

On Thu, Mar 26, 2026 at 08:18:24PM +0000, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
> 
> Change 2d8b7f9bf8e6e ("tracing: Have show_event_trigger/filter format a bit more in columns")
> added space padding to align the output.
> However it used ("%*.s", len, "") which requests the default precision.
> It doesn't matter here whether the userspace default (0) or kernel
> default (no precision) is used, but the format should be "%*s".
> 
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
>  kernel/trace/trace_events.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 249d1cba72c0..6b54c10f9ba4 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -1718,7 +1718,7 @@ static int t_show_filters(struct seq_file *m, void *v)
>  
>  	len = get_call_len(call);
>  
> -	seq_printf(m, "%s:%s%*.s%s\n", call->class->system,
> +	seq_printf(m, "%s:%s%*s%s\n", call->class->system,
>  		   trace_event_name(call), len, "", filter->filter_string);
>  
>  	return 0;
> @@ -1750,7 +1750,7 @@ static int t_show_triggers(struct seq_file *m, void *v)
>  	len = get_call_len(call);
>  
>  	list_for_each_entry_rcu(data, &file->triggers, list) {
> -		seq_printf(m, "%s:%s%*.s", call->class->system,
> +		seq_printf(m, "%s:%s%*s", call->class->system,
>  			   trace_event_name(call), len, "");
>  
>  		data->cmd_ops->print(m, data);
> -- 
> 2.39.5
> 

LGTM. 

Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>

-- 
Aaron Tomlin

Re: [PATCH next] tracing: Remove spurious default precision from show_event_trigger/filter formats

Posted by Petr Mladek 6 days, 7 hours ago

On Thu 2026-03-26 20:18:24, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
> 
> Change 2d8b7f9bf8e6e ("tracing: Have show_event_trigger/filter format a bit more in columns")
> added space padding to align the output.
> However it used ("%*.s", len, "") which requests the default precision.
> It doesn't matter here whether the userspace default (0) or kernel
> default (no precision) is used, but the format should be "%*s".
> 
> Signed-off-by: David Laight <david.laight.linux@gmail.com>

Makes sense. It does not change the output because it printed
an empty string "" so the precision did not matter.

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH next] tracing: Remove spurious default precision from show_event_trigger/filter formats

Posted by Steven Rostedt 6 days, 2 hours ago

On Fri, 27 Mar 2026 10:15:17 +0100
Petr Mladek <pmladek@suse.com> wrote:

> On Thu 2026-03-26 20:18:24, david.laight.linux@gmail.com wrote:
> > From: David Laight <david.laight.linux@gmail.com>
> > 
> > Change 2d8b7f9bf8e6e ("tracing: Have show_event_trigger/filter format a bit more in columns")
> > added space padding to align the output.
> > However it used ("%*.s", len, "") which requests the default precision.
> > It doesn't matter here whether the userspace default (0) or kernel
> > default (no precision) is used, but the format should be "%*s".
> > 
> > Signed-off-by: David Laight <david.laight.linux@gmail.com>  
> 
> Makes sense. It does not change the output because it printed
> an empty string "" so the precision did not matter.

Right. I use this in user space all the time, and add "%*.s" a lot.

I tested it and it doesn't change the output so I'm happy to take it
through my tree.

-- Steve
 

> 
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> 
> Best Regards,
> Petr

Re: [PATCH next] tracing: Remove spurious default precision from show_event_trigger/filter formats

Posted by Masami Hiramatsu (Google) 6 days, 16 hours ago

On Thu, 26 Mar 2026 20:18:24 +0000
david.laight.linux@gmail.com wrote:

> From: David Laight <david.laight.linux@gmail.com>
> 
> Change 2d8b7f9bf8e6e ("tracing: Have show_event_trigger/filter format a bit more in columns")
> added space padding to align the output.
> However it used ("%*.s", len, "") which requests the default precision.
> It doesn't matter here whether the userspace default (0) or kernel
> default (no precision) is used, but the format should be "%*s".
> 

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks!

> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
>  kernel/trace/trace_events.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 249d1cba72c0..6b54c10f9ba4 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -1718,7 +1718,7 @@ static int t_show_filters(struct seq_file *m, void *v)
>  
>  	len = get_call_len(call);
>  
> -	seq_printf(m, "%s:%s%*.s%s\n", call->class->system,
> +	seq_printf(m, "%s:%s%*s%s\n", call->class->system,
>  		   trace_event_name(call), len, "", filter->filter_string);
>  
>  	return 0;
> @@ -1750,7 +1750,7 @@ static int t_show_triggers(struct seq_file *m, void *v)
>  	len = get_call_len(call);
>  
>  	list_for_each_entry_rcu(data, &file->triggers, list) {
> -		seq_printf(m, "%s:%s%*.s", call->class->system,
> +		seq_printf(m, "%s:%s%*s", call->class->system,
>  			   trace_event_name(call), len, "");
>  
>  		data->cmd_ops->print(m, data);
> -- 
> 2.39.5
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>