linux-kernel - [PATCH 2/4] perf tools: Fix dso__data_read

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Date:	Wed, 20 May 2015 15:34:05 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH 2/4] perf tools: Fix dso__data_read_offset() file opening

When dso__data_read_offset/addr() is called without prior
dso__data_fd() (or other functions which call it internally), it
failed to open dso in data_file_size() since its binary type was not
identified.

However calling dso__data_fd() in dso__data_read_offset() will hurt
performance as it grabs a global lock everytime.  So factor out the
loop on the binary type in dso__data_fd(), and call it from both.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/dso.c | 44 ++++++++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 20 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 1b96c8d18435..a3984beca723 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -440,15 +440,7 @@ void dso__data_close(struct dso *dso)
 	pthread_mutex_unlock(&dso__data_open_lock);
 }
 
-/**
- * dso__data_fd - Get dso's data file descriptor
- * @dso: dso object
- * @machine: machine object
- *
- * External interface to find dso's file, open it and
- * returns file descriptor.
- */
-int dso__data_fd(struct dso *dso, struct machine *machine)
+static void try_to_open_dso(struct dso *dso, struct machine *machine)
 {
 	enum dso_binary_type binary_type_data[] = {
 		DSO_BINARY_TYPE__BUILD_ID_CACHE,
@@ -457,14 +449,6 @@ int dso__data_fd(struct dso *dso, struct machine *machine)
 	};
 	int i = 0;
 
-	if (dso->data.status == DSO_DATA_STATUS_ERROR)
-		return -1;
-
-	pthread_mutex_lock(&dso__data_open_lock);
-
-	if (dso->data.fd >= 0)
-		goto out;
-
 	if (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND) {
 		dso->data.fd = open_dso(dso, machine);
 		goto out;
@@ -475,14 +459,34 @@ int dso__data_fd(struct dso *dso, struct machine *machine)
 
 		dso->data.fd = open_dso(dso, machine);
 		if (dso->data.fd >= 0)
-			goto out;
+			break;
 
 	} while (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND);
+
 out:
 	if (dso->data.fd >= 0)
 		dso->data.status = DSO_DATA_STATUS_OK;
 	else
 		dso->data.status = DSO_DATA_STATUS_ERROR;
+}
+
+/**
+ * dso__data_fd - Get dso's data file descriptor
+ * @dso: dso object
+ * @machine: machine object
+ *
+ * External interface to find dso's file, open it and
+ * returns file descriptor.
+ */
+int dso__data_fd(struct dso *dso, struct machine *machine)
+{
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+
+	pthread_mutex_lock(&dso__data_open_lock);
+
+	if (dso->data.fd < 0)
+		try_to_open_dso(dso, machine);
 
 	pthread_mutex_unlock(&dso__data_open_lock);
 	return dso->data.fd;
@@ -709,10 +713,10 @@ static int data_file_size(struct dso *dso, struct machine *machine)
 	 * file (dso) due to open file limit (RLIMIT_NOFILE).
 	 */
 	if (dso->data.fd < 0) {
-		dso->data.fd = open_dso(dso, machine);
+		try_to_open_dso(dso, machine);
+
 		if (dso->data.fd < 0) {
 			ret = -errno;
-			dso->data.status = DSO_DATA_STATUS_ERROR;
 			goto out;
 		}
 	}
-- 
2.4.0

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