perf_pin_task_context() can return NULL but perf_event_init_context()
assumes it will not, correct this.
Reported-by: NVince Weaver <vincent.weaver@maine.edu>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/20140505171428.GU26782@laptop.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>