[PATCH] perf, tools: Add better errors to annotate

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

When the browser fails to annotate it is difficult for users to find
out what went wrong.

Add some errors for objdump failures that are displayed in the UI.

Note it would be event better to handle these errors smarter, like
falling back to the binary when the debug info is somehow
corrupted. But for now just giving a better error is an improvement.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/util/annotate.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index d1eece7..07f9544 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1081,6 +1081,7 @@ int symbol__annotate(struct symbol *sym, struct map *map, size_t privsize)
 	struct kcore_extract kce;
 	bool delete_extract = false;
 	int lineno = 0;
+	int nline;
 
 	if (filename)
 		symbol__join_symfs(symfs_filename, filename);
@@ -1176,6 +1177,9 @@ fallback:
 
 		ret = decompress_to_file(m.ext, symfs_filename, fd);
 
+		if (ret)
+			pr_err("Cannot decompress %s %s\n", m.ext, symfs_filename);
+
 		free(m.ext);
 		close(fd);
 
@@ -1201,13 +1205,25 @@ fallback:
 	pr_debug("Executing: %s\n", command);
 
 	file = popen(command, "r");
-	if (!file)
+	if (!file) {
+		pr_err("Failure running %s\n", command);
+		/*
+		 * If we were using debug info should retry with
+		 * original binary.
+		 */
 		goto out_remove_tmp;
+	}
 
-	while (!feof(file))
+	nline = 0;
+	while (!feof(file)) {
 		if (symbol__parse_objdump_line(sym, map, file, privsize,
 			    &lineno) < 0)
 			break;
+		nline++;
+	}
+
+	if (nline == 0)
+		pr_err("No output from %s\n", command);
 
 	/*
 	 * kallsyms does not have symbol sizes so there may a nop at the end.
-- 
2.4.3