perf_counter: rework ioctl()s

Corey noticed that ioctl()s on grouped counters didn't work on
the whole group. This extends the ioctl() interface to take a
second argument that is interpreted as a flags field. We then
provide PERF_IOC_FLAG_GROUP to toggle the behaviour.

Having this flag gives the greatest flexibility, allowing you
to individually enable/disable/reset counters in a group, or
all together.

[ Impact: fix group counter enable/disable semantics ]

Reported-by: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090508170028.837558214@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 3 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 00081d84169f..88f863ec2748 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -157,10 +157,14 @@ struct perf_counter_hw_event {
 /*
  * Ioctls that can be done on a perf counter fd:
  */
-#define PERF_COUNTER_IOC_ENABLE         _IO ('$', 0)
-#define PERF_COUNTER_IOC_DISABLE        _IO ('$', 1)
+#define PERF_COUNTER_IOC_ENABLE         _IOW('$', 0, u32)
+#define PERF_COUNTER_IOC_DISABLE        _IOW('$', 1, u32)
 #define PERF_COUNTER_IOC_REFRESH        _IOW('$', 2, u32)
-#define PERF_COUNTER_IOC_RESET          _IO ('$', 3)
+#define PERF_COUNTER_IOC_RESET          _IOW('$', 3, u32)
+
+enum perf_counter_ioc_flags {
+        PERF_IOC_FLAG_GROUP             = 1U << 0,
+};
 
 /*
  * Structure of the page that can be mapped via mmap