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

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Date:   Mon, 28 Sep 2020 13:21:33 +0300
From:   alexander.antonov@...ux.intel.com
To:     peterz@...radead.org, linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     alexander.shishkin@...ux.intel.com, kan.liang@...ux.intel.com,
        alexey.budankov@...ux.intel.com, ak@...ux.intel.com,
        acme@...nel.org, mingo@...hat.com,
        alexander.antonov@...ux.intel.com, kyle.meyer@....com, rja@....com
Subject: [PATCH] perf/x86/intel/uncore: Fix for iio mapping on Skylake Server

From: Alexander Antonov <alexander.antonov@...ux.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@....com>
Suggested-by: Kan Liang <kan.liang@...ux.intel.com>
Reviewed-by: Alexei Budankov <alexey.budankov@...ux.intel.com>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
Signed-off-by: Alexander Antonov <alexander.antonov@...ux.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