perf_counter: fix warning & lockup

 - remove bogus warning
 - fix wakeup from NMI path lockup
 - also fix up whitespace noise in perf_counter.h

Cc: 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: <20090525153931.703093461@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/perf_counter.c

@@ -2576,7 +2576,7 @@ static void perf_log_throttle(struct perf_counter *counter, int enable)
 		.time = sched_clock(),
 	};
 
-	ret = perf_output_begin(&handle, counter, sizeof(throttle_event), 0, 0);
+	ret = perf_output_begin(&handle, counter, sizeof(throttle_event), 1, 0);
 	if (ret)
 		return;
 
@@ -3449,8 +3449,6 @@ void perf_counter_exit_task(struct task_struct *child)
 	struct perf_counter_context *child_ctx;
 	unsigned long flags;
 
-	WARN_ON_ONCE(child != current);
-
 	child_ctx = child->perf_counter_ctxp;
 
 	if (likely(!child_ctx))