perf_counter: Change pctrl() behaviour

Instead of en/dis-abling all counters acting on a particular
task, en/dis- able all counters we created.

[ v2: fix crash on first counter enable ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.916937244@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/init_task.h

@@ -108,6 +108,15 @@ extern struct group_info init_groups;
 
 extern struct cred init_cred;
 
+#ifdef CONFIG_PERF_COUNTERS
+# define INIT_PERF_COUNTERS(tsk)					\
+	.perf_counter_mutex = 						\
+		 __MUTEX_INITIALIZER(tsk.perf_counter_mutex),		\
+	.perf_counter_list = LIST_HEAD_INIT(tsk.perf_counter_list),
+#else
+# define INIT_PERF_COUNTERS(tsk)
+#endif
+
 /*
  *  INIT_TASK is used to set up the first task table, touch at
  * your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -171,6 +180,7 @@ extern struct cred init_cred;
 	},								\
 	.dirties = INIT_PROP_LOCAL_SINGLE(dirties),			\
 	INIT_IDS							\
+	INIT_PERF_COUNTERS(tsk)						\
 	INIT_TRACE_IRQFLAGS						\
 	INIT_LOCKDEP							\
 	INIT_FTRACE_GRAPH						\

include/linux/perf_counter.h

@@ -469,6 +469,9 @@ struct perf_counter {
 	int				oncpu;
 	int				cpu;
 
+	struct list_head		owner_entry;
+	struct task_struct		*owner;
+
 	/* mmap bits */
 	struct mutex			mmap_mutex;
 	atomic_t			mmap_count;

include/linux/sched.h

@@ -1389,6 +1389,8 @@ struct task_struct {
 #endif
 #ifdef CONFIG_PERF_COUNTERS
 	struct perf_counter_context *perf_counter_ctxp;
+	struct mutex perf_counter_mutex;
+	struct list_head perf_counter_list;
 #endif
 #ifdef CONFIG_NUMA
 	struct mempolicy *mempolicy;