linux-kernel - [PATCH] perf tools: Dont use openat()

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Date:	Thu, 24 Sep 2009 15:39:09 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frédéric Weisbecker 
	<fweisbec@...il.com>, Ulrich Drepper <drepper@...hat.com>,
	linux kernel <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: [PATCH] perf tools: Dont use openat()

Ingo Molnar a écrit :
> * Eric Dumazet <eric.dumazet@...il.com> wrote:
> 
>> Hi Ingo
>>
>> Here is a patch for perf.
> 
> Applied, thanks Eric!
> 
>> BTW, use of openat() is a nuisance, since many machines have old glibc
>> (RHEL 4 Update 5 -> glibc-2.3.4-2.36 on my dev machine for example)
> 
> We can certainly remove that reliance - wanna send a patch for it?

Here it is

Thanks

[PATCH] perf tools: Dont use openat()

openat() is still a young glibc facility, better to not use it
in a non performance critical program (perf list)

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
 tools/perf/util/parse-events.c |   49 ++++++++++++-------------------
 1 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 13ab4b8..865208d 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -165,33 +165,31 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
 	DIR *sys_dir, *evt_dir;
 	struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
 	char id_buf[4];
-	int sys_dir_fd, fd;
+	int fd;
 	u64 id;
 	char evt_path[MAXPATHLEN];
+	char dir_path[MAXPATHLEN];
 
 	if (valid_debugfs_mount(debugfs_path))
 		return NULL;
 
 	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
-		goto cleanup;
-	sys_dir_fd = dirfd(sys_dir);
+		return NULL;
 
 	for_each_subsystem(sys_dir, sys_dirent, sys_next) {
-		int dfd = openat(sys_dir_fd, sys_dirent.d_name,
-				 O_RDONLY|O_DIRECTORY), evt_dir_fd;
-		if (dfd == -1)
-			continue;
-		evt_dir = fdopendir(dfd);
-		if (!evt_dir) {
-			close(dfd);
+
+		snprintf(dir_path, MAXPATHLEN, "%s/%s", debugfs_path,
+			 sys_dirent.d_name);
+		evt_dir = opendir(dir_path);
+		if (!evt_dir)
 			continue;
-		}
-		evt_dir_fd = dirfd(evt_dir);
+
 		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) {
-			snprintf(evt_path, MAXPATHLEN, "%s/id",
+			
+			snprintf(evt_path, MAXPATHLEN, "%s/%s/id", dir_path,
 				 evt_dirent.d_name);
-			fd = openat(evt_dir_fd, evt_path, O_RDONLY);
+			fd = open(evt_path, O_RDONLY);
 			if (fd < 0)
 				continue;
 			if (read(fd, id_buf, sizeof(id_buf)) < 0) {
@@ -225,7 +223,6 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
 		closedir(evt_dir);
 	}
 
-cleanup:
 	closedir(sys_dir);
 	return NULL;
 }
@@ -761,28 +758,24 @@ static void print_tracepoint_events(void)
 {
 	DIR *sys_dir, *evt_dir;
 	struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
-	int sys_dir_fd;
 	char evt_path[MAXPATHLEN];
+	char dir_path[MAXPATHLEN];
 
 	if (valid_debugfs_mount(debugfs_path))
 		return;
 
 	sys_dir = opendir(debugfs_path);
 	if (!sys_dir)
-		goto cleanup;
-	sys_dir_fd = dirfd(sys_dir);
+		return;
 
 	for_each_subsystem(sys_dir, sys_dirent, sys_next) {
-		int dfd = openat(sys_dir_fd, sys_dirent.d_name,
-				 O_RDONLY|O_DIRECTORY), evt_dir_fd;
-		if (dfd == -1)
-			continue;
-		evt_dir = fdopendir(dfd);
-		if (!evt_dir) {
-			close(dfd);
+
+		snprintf(dir_path, MAXPATHLEN, "%s/%s", debugfs_path,
+			 sys_dirent.d_name);
+		evt_dir = opendir(dir_path);
+		if (!evt_dir)
 			continue;
-		}
-		evt_dir_fd = dirfd(evt_dir);
+
 		for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) {
 			snprintf(evt_path, MAXPATHLEN, "%s:%s",
 				 sys_dirent.d_name, evt_dirent.d_name);
@@ -791,8 +784,6 @@ static void print_tracepoint_events(void)
 		}
 		closedir(evt_dir);
 	}
-
-cleanup:
 	closedir(sys_dir);
 }
 
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