Re: [PATCH] trace-cmd: fix kvm_mmu_prepare_zap_page even name and kvm_mmu_get_page event output in kvm plugin

[Gleb Natapov <gleb@redhat.com>]

On Wed, Dec 26, 2012 at 08:58:30AM -0500, Steven Rostedt wrote:
> On Tue, 2012-12-25 at 13:46 +0200, Gleb Natapov wrote:
> > kvm_mmu_zap_page even was renamed to kvm_mmu_prepare_zap_page.
> > Print out created field for kvm_mmu_get_page event.
> 
> trace-cmd needs to be backward compatible with older kernels. If older
> kernels used kvm_mmu_zap_page, then please add a check for that and have
> the plugin cope with either one.
> 
Something like this?

        if (pevent_find_event_by_name(pevent, "kvmmmu", "kvm_mmu_prepare_zap_page"))
                pevent_register_event_handler(pevent, -1, "kvmmmu",
                                "kvm_mmu_prepare_zap_page", kvm_mmu_print_role,
                                NULL);
        else
                pevent_register_event_handler(pevent, -1, "kvmmmu",
                                "kvm_mmu_zap_page", kvm_mmu_print_role, NULL);

Also when trace-cmd encounters an event it does not recognize it prints
mysterious message:

trace-cmd: No such file or directory
  bad op token {

Is this a bug?

> Thanks,
> 
> -- Steve
> 
> > 
> > Signed-off-by: Gleb Natapov <gleb@redhat.com>
> > diff --git a/plugin_kvm.c b/plugin_kvm.c
> > index 55812ef..adc5694 100644
> > --- a/plugin_kvm.c
> > +++ b/plugin_kvm.c
> > @@ -382,7 +382,7 @@ static int kvm_mmu_print_role(struct trace_seq *s, struct pevent_record *record,
> >  	} else
> >  		trace_seq_printf(s, "WORD: %08x", role.word);
> >  
> > -	pevent_print_num_field(s, " root %u",  event,
> > +	pevent_print_num_field(s, " root %u ",  event,
> >  			       "root_count", record, 1);
> >  
> >  	if (pevent_get_field_val(s, event, "unsync", record, &val, 1) < 0)
> > @@ -397,6 +397,11 @@ static int kvm_mmu_get_page_handler(struct trace_seq *s, struct pevent_record *r
> >  {
> >  	unsigned long long val;
> >  
> > +	if (pevent_get_field_val(s, event, "created", record, &val, 1) < 0)
> > +		return -1;
> > +
> > +	trace_seq_printf(s, "%s ", val ? "new" : "existing");
> > +
> >  	if (pevent_get_field_val(s, event, "gfn", record, &val, 1) < 0)
> >  		return -1;
> >  
> > @@ -430,7 +435,7 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
> >  	pevent_register_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_unsync_page",
> >  				      kvm_mmu_print_role, NULL);
> >  
> > -	pevent_register_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_zap_page",
> > +	pevent_register_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_prepare_zap_page",
> >  				      kvm_mmu_print_role, NULL);
> >  
> >  	return 0;
> > --
> > 			Gleb.
> 

--
			Gleb.