Re: [PATCH v3] trace:Add "gfp_t" support in synthetic_events

[Tom Zanussi]

Hi Steve,

On Wed, 2019-09-04 at 06:43 -0400, Steven Rostedt wrote:
> On Fri, 12 Jul 2019 11:05:06 -0500
> Tom Zanussi <zanussi@xxxxxxxxxx> wrote:
> 
> > Hi Zhengjun,
> > 
> > On Fri, 2019-07-12 at 09:53 +0800, Zhengjun Xing wrote:
> > > Add "gfp_t" support in synthetic_events, then the "gfp_t" type
> > > parameter in some functions can be traced.
> > > 
> > > Prints the gfp flags as hex in addition to the human-readable
> > > flag
> > > string.  Example output:
> > > 
> > >   whoopsie-630 [000] ...1 78.969452: testevent: bar=b20
> > > (GFP_ATOMIC|__GFP_ZERO)
> > >     rcuc/0-11  [000] ...1 81.097555: testevent: bar=a20
> > > (GFP_ATOMIC)
> > >     rcuc/0-11  [000] ...1 81.583123: testevent: bar=a20
> > > (GFP_ATOMIC)
> > > 
> > > Signed-off-by: Tom Zanussi <zanussi@xxxxxxxxxx>
> 
> Why is this Signed-off-by Tom? Tom, did you author part of this??
> 

Yeah, I added the part that prints the flag names.

Tom

> -- Steve
> 
> > > Signed-off-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>  
> > 
> > Looks good to me, thanks!
> > 
> > Tom
> > 
> > > ---
> > >  kernel/trace/trace_events_hist.c | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > > 
> > > diff --git a/kernel/trace/trace_events_hist.c
> > > b/kernel/trace/trace_events_hist.c
> > > index ca6b0dff60c5..30f0f32aca62 100644
> > > --- a/kernel/trace/trace_events_hist.c
> > > +++ b/kernel/trace/trace_events_hist.c
> > > @@ -13,6 +13,10 @@
> > >  #include <linux/rculist.h>
> > >  #include <linux/tracefs.h>
> > >  
> > > +/* for gfp flag names */
> > > +#include <linux/trace_events.h>
> > > +#include <trace/events/mmflags.h>
> > > +
> > >  #include "tracing_map.h"
> > >  #include "trace.h"
> > >  #include "trace_dynevent.h"
> > > @@ -752,6 +756,8 @@ static int synth_field_size(char *type)
> > >  		size = sizeof(unsigned long);
> > >  	else if (strcmp(type, "pid_t") == 0)
> > >  		size = sizeof(pid_t);
> > > +	else if (strcmp(type, "gfp_t") == 0)
> > > +		size = sizeof(gfp_t);
> > >  	else if (synth_field_is_string(type))
> > >  		size = synth_field_string_size(type);
> > >  
> > > @@ -792,6 +798,8 @@ static const char *synth_field_fmt(char
> > > *type)
> > >  		fmt = "%lu";
> > >  	else if (strcmp(type, "pid_t") == 0)
> > >  		fmt = "%d";
> > > +	else if (strcmp(type, "gfp_t") == 0)
> > > +		fmt = "%x";
> > >  	else if (synth_field_is_string(type))
> > >  		fmt = "%s";
> > >  
> > > @@ -834,9 +842,20 @@ static enum print_line_t
> > > print_synth_event(struct trace_iterator *iter,
> > >  					 i == se->n_fields - 1 ?
> > > ""
> > > : " ");
> > >  			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
> > >  		} else {
> > > +			struct trace_print_flags __flags[] = {
> > > +			    __def_gfpflag_names, {-1, NULL} };
> > > +
> > >  			trace_seq_printf(s, print_fmt, se-  
> > > > fields[i]->name,  
> > > 
> > >  					 entry->fields[n_u64],
> > >  					 i == se->n_fields - 1 ?
> > > ""
> > > : " ");
> > > +
> > > +			if (strcmp(se->fields[i]->type, "gfp_t")
> > > ==
> > > 0) {
> > > +				trace_seq_puts(s, " (");
> > > +				trace_print_flags_seq(s, "|",
> > > +						      entry-  
> > > > fields[n_u64],  
> > > 
> > > +						      __flags);
> > > +				trace_seq_putc(s, ')');
> > > +			}
> > >  			n_u64++;
> > >  		}
> > >  	}  
> 
>