Re: [PATCH] perf/x86/intel/uncore: Fix for iio mapping on Skylake Server

["Meyer, Kyle" <kyle.meyer@hpe.com>]

Hello Alexander,

Do you plan on supporting multiple segment platforms?

Thanks,
Kyle Meyer

________________________________________
From: alexander.antonov@linux.intel.com <alexander.antonov@linux.intel.com>
Sent: Monday, September 28, 2020 5:21 AM
To: peterz@infradead.org; linux-kernel@vger.kernel.org; x86@kernel.org
Cc: alexander.shishkin@linux.intel.com; kan.liang@linux.intel.com; alexey.budankov@linux.intel.com; ak@linux.intel.com; acme@kernel.org; mingo@redhat.com; alexander.antonov@linux.intel.com; Meyer, Kyle; Anderson, Russ
Subject: [PATCH] perf/x86/intel/uncore: Fix for iio mapping on Skylake Server

From: Alexander Antonov <alexander.antonov@linux.intel.com>

Introduced early attributes /sys/devices/uncore_iio_<pmu_idx>/die* are
initialized by skx_iio_set_mapping(), however, for example, for multiple
segment platforms skx_iio_get_topology() returns -EPERM before a list of
attributes in skx_iio_mapping_group will have been initialized.
As a result the list is being NULL. Thus the warning
"sysfs: (bin_)attrs not set by subsystem for group: uncore_iio_*/" appears
and uncore_iio pmus are not available in sysfs. Clear IIO attr_update
to properly handle the cases when topology information cannot be
retrieved.

Fixes: bb42b3d39781 ("perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping")
Reported-by: Kyle Meyer <kyle.meyer@hpe.com>
Suggested-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Alexei Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
---
 arch/x86/events/intel/uncore_snbep.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 62e88ad919ff..ccfa1d6b6aa0 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3749,7 +3749,9 @@ static int skx_iio_set_mapping(struct intel_uncore_type *type)

        ret = skx_iio_get_topology(type);
        if (ret)
-               return ret;
+               goto clear_attr_update;
+
+       ret = -ENOMEM;

        /* One more for NULL. */
        attrs = kcalloc((uncore_max_dies() + 1), sizeof(*attrs), GFP_KERNEL);
@@ -3781,8 +3783,9 @@ static int skx_iio_set_mapping(struct intel_uncore_type *type)
        kfree(eas);
        kfree(attrs);
        kfree(type->topology);
+clear_attr_update:
        type->attr_update = NULL;
-       return -ENOMEM;
+       return ret;
 }

 static void skx_iio_cleanup_mapping(struct intel_uncore_type *type)

base-commit: a1b8638ba1320e6684aa98233c15255eb803fac7
--
2.19.1