Re: [PATCH v2] tracing: Add verbose gfp_flag printing to synthetic events

[Xing Zhengjun]

Hi Tom,

On 7/11/2019 11:42 PM, Tom Zanussi wrote:
> Hi Zhengjun,
>
> The patch itself looks fine to me, but could you please create a v3
> with a couple changes to the commit message?  I noticed you dropped
> your original commit message - please add it back and combine with part
> of mine, as below.  Also, please keep your original Subject line
> ('[PATCH] trace:add "gfp_t" support in synthetic_events') (but the
> first word after trace:, 'add', should be capitalized.)
Thanks. I will send v3 version patch soon.

> On Thu, 2019-07-11 at 16:46 +0800, Zhengjun Xing wrote:
> > Add on top of 'trace:add "gfp_t" support in synthetic_events'.
>
> Please remove this part but keep the part below.
>
> > 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)
>
> So basically, something like this:
>
> [PATCH] trace: Add "gfp_t" support in synthetic_events
>
> Add "gfp_t" support in synthetic_events, then the "gfp_t" type
> parameter in some functions can be traced.
>
> Print 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>
> > Signed-off-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>
>
>
> 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..938ef3f54c5c 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 +838,20 @@ 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++;
> >   		}
> >   	}

--
Zhengjun Xing