Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 2/3] perf x86: Add compaction function for uncore attributes | From | "Sudarikov, Roman" <> | Date | Wed, 11 Dec 2019 17:21:42 +0300 |
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On 10.12.2019 13:37, Peter Zijlstra wrote: > On Tue, Dec 10, 2019 at 12:14:50PM +0300, roman.sudarikov@linux.intel.com wrote: >> From: Roman Sudarikov <roman.sudarikov@linux.intel.com> >> >> In current design, there is an implicit assumption that array of pointers >> to uncore type attributes is NULL terminated. However, not all attributes >> are mandatory for each Uncore unit type, e.g. "events" is required for >> IMC but doesn't exist for CHA. That approach correctly supports only one >> optional attribute which also must be the last in the row. >> The patch removes limitation by safely removing embedded NULL elements. >> >> Co-developed-by: Alexander Antonov <alexander.antonov@intel.com> >> Signed-off-by: Alexander Antonov <alexander.antonov@intel.com> >> Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com> >> --- >> arch/x86/events/intel/uncore.c | 22 ++++++++++++++++++++++ >> 1 file changed, 22 insertions(+) >> >> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c >> index 24e120289018..a05352c4fc01 100644 >> --- a/arch/x86/events/intel/uncore.c >> +++ b/arch/x86/events/intel/uncore.c >> @@ -923,6 +923,22 @@ static void uncore_types_exit(struct intel_uncore_type **types) >> uncore_type_exit(*types); >> } >> >> +static void uncore_type_attrs_compaction(struct intel_uncore_type *type) >> +{ >> + int i, j; >> + int size = ARRAY_SIZE(type->attr_groups); >> + >> + for (i = 0, j = 0; i < size; i++) { >> + if (!type->attr_groups[i]) >> + continue; >> + if (i > j) { >> + type->attr_groups[j] = type->attr_groups[i]; >> + type->attr_groups[i] = NULL; >> + } >> + j++; >> + } >> +} > GregKH had objections to us playing silly games like that and made us > use is_visible() for the regular PMU driver. Also see commit: > > baa0c83363c7 ("perf/x86: Use the new pmu::update_attrs attribute group")
Removed theuncore_type_attrs_compaction() function and implemented Kan's suggestion to replace NULL events_group by the empty attributes group:
diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c index e8532923bd45..110b3603f56f 100644 --- a/arch/x86/events/intel/uncore.c +++ b/arch/x86/events/intel/uncore.c @@ -923,6 +923,14 @@ static void uncore_types_exit(struct intel_uncore_type **types) uncore_type_exit(*types); }
+static struct attribute *empty_attrs[] = { + NULL, +}; + +static const struct attribute_group empty_group = { + .attrs = empty_attrs, +}; + static int __init uncore_type_init(struct intel_uncore_type *type, bool setid) { struct intel_uncore_pmu *pmus; @@ -968,7 +976,8 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid) attr_group->attrs[j] = &type->event_descs[j].attr.attr;
type->events_group = &attr_group->group; - } + } else + type->events_group = &empty_group;
type->pmu_group = &uncore_pmu_attr_group;
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