[DTrace-devel] [PATCH 03/05] agg: report error if aggsize is too small

[Kris Van Hees]

On Mon, May 08, 2023 at 12:33:38PM -0400, Eugene Loh via DTrace-devel wrote:
> Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
> but...
> 
> On 5/5/23 11:31, Kris Van Hees via DTrace-devel wrote:
> > When aggregations are used, ensure that the aggsize value is sufficient
> > to hold at least a single aggregation.
> 
> This comment does not hold.  In fact, it conflicts with the subject line.

Yes, foolishly forgot to update that.  Fixed.

> > Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> > ---
> >   libdtrace/dt_bpf.c                         |  3 +--
> >   test/unittest/aggs/err.aggsize-too-small.d | 26 ++++++++++++++++++++++
> >   test/unittest/aggs/err.aggsize-too-small.r |  3 +++
> >   3 files changed, 30 insertions(+), 2 deletions(-)
> >   create mode 100644 test/unittest/aggs/err.aggsize-too-small.d
> >   create mode 100644 test/unittest/aggs/err.aggsize-too-small.r
> > 
> > diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
> > index 18aa07af..b553b33f 100644
> > --- a/libdtrace/dt_bpf.c
> > +++ b/libdtrace/dt_bpf.c
> > @@ -520,9 +520,8 @@ gmap_create_aggs(dtrace_hdl_t *dtp)
> >   	nelems = dtp->dt_options[DTRACEOPT_AGGSIZE] /
> >   		 (dtp->dt_maxtuplesize + dtp->dt_maxaggdsize);
> > -
> >   	if (nelems == 0)
> > -		return 0;
> > +		return dt_set_errno(dtp, EDT_BUFTOOSMALL);
> >   	dtp->dt_aggmap_fd = create_gmap_of_maps(dtp, "aggs",
> >   						BPF_MAP_TYPE_ARRAY_OF_MAPS,
> > diff --git a/test/unittest/aggs/err.aggsize-too-small.d b/test/unittest/aggs/err.aggsize-too-small.d
> > new file mode 100644
> > index 00000000..8bd12381
> > --- /dev/null
> > +++ b/test/unittest/aggs/err.aggsize-too-small.d
> > @@ -0,0 +1,26 @@
> > +/*
> > + * Oracle Linux DTrace.
> > + * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
> > + * Licensed under the Universal Permissive License v 1.0 as shown at
> > + * http://oss.oracle.com/licenses/upl.
> > + */
> > +
> > +/*
> > + * ASSERTION: If aggsize is too small to hold a single aggregation, report an
> > + *	      error.
> > + *
> > + * SECTION: Aggregations/Aggregations
> > + */
> > +
> > +#pragma D option aggsize=8
> > +
> > +BEGIN
> > +{
> > +	@ = count();
> > +	exit(0);
> > +}
> > +
> > +ERROR
> > +{
> > +	exit(0);
> > +}
> > diff --git a/test/unittest/aggs/err.aggsize-too-small.r b/test/unittest/aggs/err.aggsize-too-small.r
> > new file mode 100644
> > index 00000000..b0a37c5d
> > --- /dev/null
> > +++ b/test/unittest/aggs/err.aggsize-too-small.r
> > @@ -0,0 +1,3 @@
> > +-- @@stderr --
> > +dtrace: script 'test/unittest/aggs/err.aggsize-too-small.d' matched 2 probes
> > +dtrace: could not enable tracing: Enabling exceeds size of buffer
> 
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