[PATCH v10 03/10] lib/pmu: quiesce rte_pmu_read deprecation warning in chkincs

[David Marchand]

On Fri, 17 Oct 2025 at 08:58, Tomasz Duszynski <tduszynski at marvell.com> wrote:
>
> > > > > Add a dummy rte_pmu_read() definition for chkincs when
> > > > > ALLOW_EXPERIMENTAL_API is not defined to suppress warnings from
> > > > > use of experimental APIs in tracepoints.
> > > > >
> > > > > Fixes: 960c43184c4d ("pmu: introduce library for reading PMU events")
> > > > >
> > > > > Signed-off-by: Tomasz Duszynski <tduszynski at marvell.com>
> > > > > ---
> > > > >  lib/pmu/rte_pmu.h | 4 ++++
> > > > >  1 file changed, 4 insertions(+)
> > > > >
> > > > > diff --git a/lib/pmu/rte_pmu.h b/lib/pmu/rte_pmu.h
> > > > > index 57b634ecd8..84a5d522d1 100644
> > > > > --- a/lib/pmu/rte_pmu.h
> > > > > +++ b/lib/pmu/rte_pmu.h
> > > > > @@ -232,6 +232,10 @@ rte_pmu_read(unsigned int index)
> > > > >
> > > > >         return __rte_pmu_read_userpage(group->mmap_pages[index]);
> > > > >  }
> > > > > +/* quiesce warnings produced by chkincs */
> > > > > +#ifndef ALLOW_EXPERIMENTAL_API
> > > > > +#define rte_pmu_read(pc) ({ RTE_SET_USED(pc); 0; })
> > > > > +#endif
> > > >
> > > > Seems like an awkward solution I would rather that fix chkincs
> > > > or restructure this.
> > > >
> > > > The way you are doing it will cause the checks for use
> > > > of experimental API to not work.
> > >
> > > No matter how I shuffle things around, the experimental API keeps getting called from
> > > non-experimental code, so those warnings will show up.. Fixing chkincs would mean telling it to
> > > skip checks for this library, which is basically what I'm already doing here.
> > >
> > > Dropping experimental tag feels too soon. The library still needs some time to bake.
> > >
> > > So, unless anyone has got other ideas, which is the better trade off here: yanking experimental
> > > tags or tweaking chkincs to ignore the library checks?
> >

What we have been doing in other libraries is to hide calls to
experimental symbols in inline helpers, which is the issue here,
right?
Then add a RTE_VERIFY(false) so that an abort is triggered at runtime
in case an application called this helper.

See a3e126fd58d1 ("bitset: fix build for GCC without experimental
API") for example.


I see the same #define hiding for __rte_pmu_enable_group and
__rte_pmu_read_userpage.
Something like below should be applied on main before looking at this
new series.

$ git diff
diff --git a/lib/pmu/rte_pmu.h b/lib/pmu/rte_pmu.h
index 57b634ecd8..fcf125a908 100644
--- a/lib/pmu/rte_pmu.h
+++ b/lib/pmu/rte_pmu.h
@@ -31,6 +31,7 @@
 #include <rte_branch_prediction.h>
 #include <rte_common.h>
 #include <rte_compat.h>
+#include <rte_debug.h>
 #include <rte_lcore.h>

 #define RTE_PMU_SUPPORTED
@@ -181,12 +182,6 @@ __rte_experimental
 int
 rte_pmu_add_event(const char *name);

-/* quiesce warnings produced by chkincs caused by calling internal
functions directly */
-#ifndef ALLOW_EXPERIMENTAL_API
-#define __rte_pmu_enable_group(group) ({ RTE_SET_USED(group); 0; })
-#define __rte_pmu_read_userpage(pc) ({ RTE_SET_USED(pc); 0; })
-#endif
-
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
@@ -211,6 +206,7 @@ __rte_experimental
 static __rte_always_inline uint64_t
 rte_pmu_read(unsigned int index)
 {
+#ifdef ALLOW_EXPERIMENTAL_API
        unsigned int lcore_id = rte_lcore_id();
        struct rte_pmu_event_group *group;

@@ -231,6 +227,10 @@ rte_pmu_read(unsigned int index)
        }

        return __rte_pmu_read_userpage(group->mmap_pages[index]);
+#else
+       RTE_SET_USED(index);
+       RTE_VERIFY(false);
+#endif
 }

 #ifdef __cplusplus


-- 
David Marchand