perf/x86: Check perf_callchain_store() error

Add a check to perf_callchain_kernel() so that it returns early if the
callchain entry array is already full.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/dce6d60bab08be2600efd90021d9b85620646161.1472057064.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/core.c

@@ -2277,7 +2277,8 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 		return;
 	}
 
-	perf_callchain_store(entry, regs->ip);
+	if (perf_callchain_store(entry, regs->ip))
+		return;
 
 	dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
 }