tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty
authorOleg Nesterov <oleg@redhat.com>
Mon, 17 Jun 2013 17:02:07 +0000 (19:02 +0200)
committerSteven Rostedt <rostedt@goodmis.org>
Fri, 19 Jul 2013 01:31:28 +0000 (21:31 -0400)
commit421c7860c6e1989da3962fafdd6699316c9f8e20
treea3247de06867de070ae709bcdca412e0a7900d62
parentb8ebfd3f7113b63dda93d76bfec638c00e6bd514
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>
kernel/trace/trace_syscalls.c