[PATCH] perf_counter: extensible perf_counter_attr

[Peter Zijlstra <peterz@infradead.org>]

Allow extending the perf_counter_attr structure by linking extended
structures to it.

Also, should we grow the directly reserved space in the structure a
little more?

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/perf_counter.h |    7 +++++++
 kernel/perf_counter.c        |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 3586df8..781d8ce 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -175,6 +175,13 @@ struct perf_counter_attr {
 	__u32			__reserved_3;
 
 	__u64			__reserved_4;
+
+	struct perf_counter_attr_ext *ext_attrs;
+};
+
+struct perf_counter_attr_ext {
+	struct perf_counter_attr_ext 	*next;
+	__u64				perf_attr_ext_type;
 };
 
 /*
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 5eacaaf..606f662 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3467,6 +3467,7 @@ perf_counter_alloc(struct perf_counter_attr *attr,
 
 	counter->cpu		= cpu;
 	counter->attr		= *attr;
+	counter->attr.ext_attrs	= NULL;
 	counter->group_leader	= group_leader;
 	counter->pmu		= NULL;
 	counter->ctx		= ctx;