perf tools: Do not disable source line lookup just because of 1 failure

Looking up an ip's source file name and line number does not succeed
always.  Current logic disables the lookup for a dso entirely on any
failure.  Change it so that disabling never happens if there has ever
been a successful lookup for that dso but disable if the first 123
lookups fail.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1386055390-13757-8-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dso.c

@@ -451,6 +451,7 @@ struct dso *dso__new(const char *name)
 		dso->sorted_by_name = 0;
 		dso->has_build_id = 0;
 		dso->has_srcline = 1;
+		dso->a2l_fails = 1;
 		dso->kernel = DSO_TYPE_USER;
 		dso->needs_swap = DSO_SWAP__UNSET;
 		INIT_LIST_HEAD(&dso->node);

tools/perf/util/dso.h

@@ -79,6 +79,7 @@ struct dso {
 	struct rb_root	 cache;
 	void		 *a2l;
 	char		 *symsrc_filename;
+	unsigned int	 a2l_fails;
 	enum dso_kernel_type	kernel;
 	enum dso_swap_type	needs_swap;
 	enum dso_binary_type	symtab_type;

tools/perf/util/srcline.c

@@ -244,6 +244,12 @@ void dso__free_a2l(struct dso *dso __maybe_unused)
 
 #endif /* HAVE_LIBBFD_SUPPORT */
 
+/*
+ * Number of addr2line failures (without success) before disabling it for that
+ * dso.
+ */
+#define A2L_FAIL_LIMIT 123
+
 char *get_srcline(struct dso *dso, unsigned long addr)
 {
 	char *file = NULL;
@@ -268,15 +274,21 @@ char *get_srcline(struct dso *dso, unsigned long addr)
 	if (!addr2line(dso_name, addr, &file, &line, dso))
 		goto out;
 
-	if (asprintf(&srcline, "%s:%u", file, line) < 0)
-		srcline = SRCLINE_UNKNOWN;
+	if (asprintf(&srcline, "%s:%u", file, line) < 0) {
+		free(file);
+		goto out;
+	}
+
+	dso->a2l_fails = 0;
 
 	free(file);
 	return srcline;
 
 out:
-	dso->has_srcline = 0;
-	dso__free_a2l(dso);
+	if (dso->a2l_fails && ++dso->a2l_fails > A2L_FAIL_LIMIT) {
+		dso->has_srcline = 0;
+		dso__free_a2l(dso);
+	}
 	return SRCLINE_UNKNOWN;
 }