tree a3247de06867de070ae709bcdca412e0a7900d62
parent b8ebfd3f7113b63dda93d76bfec638c00e6bd514
author Oleg Nesterov <oleg@redhat.com> 1371488527 +0200
committer Steven Rostedt <rostedt@goodmis.org> 1374197488 -0400

tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty

perf_trace_buf_prepare() + perf_trace_buf_submit(head, task => NULL)
make no sense if hlist_empty(head). Change perf_syscall_enter/exit()
to check sys_data->{enter,exit}_event->perf_events beforehand.

Link: http://lkml.kernel.org/r/20130617170207.GA19806@redhat.com

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>