linux-kernel - [PATCH v2 1/3] perf tools: Fix dso__data_read

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Message-Id: <1432137821-10853-1-git-send-email-namhyung@kernel.org>
Date:	Thu, 21 May 2015 01:03:39 +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>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>
Subject: [PATCH v2 1/3] 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.

Reported-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/dso.c | 59 ++++++++++++++++++++++++++++-----------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 1b96c8d18435..516e0c25ea16 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,
@@ -457,13 +449,8 @@ 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;
+		return;
 
 	if (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND) {
 		dso->data.fd = open_dso(dso, machine);
@@ -483,8 +470,25 @@ out:
 		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);
+	try_to_open_dso(dso, machine);
 	pthread_mutex_unlock(&dso__data_open_lock);
+
 	return dso->data.fd;
 }
 
@@ -609,13 +613,12 @@ dso_cache__read(struct dso *dso, struct machine *machine,
 		 * dso->data.fd might be closed if other thread opened another
 		 * file (dso) due to open file limit (RLIMIT_NOFILE).
 		 */
+		try_to_open_dso(dso, machine);
+
 		if (dso->data.fd < 0) {
-			dso->data.fd = open_dso(dso, machine);
-			if (dso->data.fd < 0) {
-				ret = -errno;
-				dso->data.status = DSO_DATA_STATUS_ERROR;
-				break;
-			}
+			ret = -errno;
+			dso->data.status = DSO_DATA_STATUS_ERROR;
+			break;
 		}
 
 		cache_offset = offset & DSO__DATA_CACHE_MASK;
@@ -702,19 +705,21 @@ static int data_file_size(struct dso *dso, struct machine *machine)
 	if (dso->data.file_size)
 		return 0;
 
+	if (dso->data.status == DSO_DATA_STATUS_ERROR)
+		return -1;
+
 	pthread_mutex_lock(&dso__data_open_lock);
 
 	/*
 	 * dso->data.fd might be closed if other thread opened another
 	 * file (dso) due to open file limit (RLIMIT_NOFILE).
 	 */
+	try_to_open_dso(dso, machine);
+
 	if (dso->data.fd < 0) {
-		dso->data.fd = open_dso(dso, machine);
-		if (dso->data.fd < 0) {
-			ret = -errno;
-			dso->data.status = DSO_DATA_STATUS_ERROR;
-			goto out;
-		}
+		ret = -errno;
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		goto out;
 	}
 
 	if (fstat(dso->data.fd, &st) < 0) {
-- 
2.4.0

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