Subject: [PATCH 0/2] debugfs utility routines for perf

Subject: [PATCH 0/2] debugfs utility routines for perf

[Clark Williams]

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Ingo,

Here are the cleaned-up debugfs routines.

Clark


Clark Williams (2):
  debugfs utility routines for perf
  modify perf routines to use new debugfs routines

 tools/perf/perf.c              |   45 +------
 tools/perf/util/debugfs.c      |  247 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/debugfs.h      |   22 ++++
 tools/perf/util/parse-events.c |   17 +--
 4 files changed, 280 insertions(+), 51 deletions(-)
 create mode 100644 tools/perf/util/debugfs.c
 create mode 100644 tools/perf/util/debugfs.h


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[PATCH 1/2] debugfs utility routines for perf

[Clark Williams]

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Add routines to locate the debugfs mount point and to manage the
mounting and unmountin of the debugfs.

Signed-off-by: Clark Williams <williams@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/debugfs.c |  247 +++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/debugfs.h |   22 ++++
 2 files changed, 269 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/util/debugfs.c
 create mode 100644 tools/perf/util/debugfs.h

diff --git a/tools/perf/util/debugfs.c b/tools/perf/util/debugfs.c
new file mode 100644
index 0000000..368b44e
--- /dev/null
+++ b/tools/perf/util/debugfs.c
@@ -0,0 +1,247 @@
+#include "util.h"
+#include "debugfs.h"
+#include "cache.h"
+
+static int debugfs_premounted;
+static char debugfs_mountpoint[MAX_PATH+1];
+
+static const char *debugfs_known_mountpoints[] = {
+	"/sys/kernel/debug/",
+	"/debug/",
+	0,
+};
+
+/* use this to force a umount */
+void debugfs_force_cleanup(void)
+{
+	debugfs_find_mountpoint();
+	debugfs_premounted = 0;
+	debugfs_umount();
+}
+
+/* construct a full path to a debugfs element */
+int debugfs_make_path(const char *element, char *buffer, int size)
+{
+	int len;
+
+	if (strlen(debugfs_mountpoint) == 0) {
+		buffer[0] = '\0';
+		return -1;
+	}
+
+	len = strlen(debugfs_mountpoint) + strlen(element) + 1;
+	if (len >= size)
+		return len+1;
+
+	snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
+	return 0;
+}
+
+/* find the path to the mounted debugfs */
+const char *
+debugfs_find_mountpoint(void)
+{
+	static int debugfs_found;
+	char type[100];
+	FILE *fp;
+	const char **ptr;
+
+	if (debugfs_found)
+		return (const char *) debugfs_mountpoint;
+
+	ptr = debugfs_known_mountpoints;
+	while (*ptr) {
+		if (debugfs_valid_mountpoint(*ptr) == 0) {
+			debugfs_found = 1;
+			strcpy(debugfs_mountpoint, *ptr);
+			return debugfs_mountpoint;
+		}
+		ptr++;
+	}
+
+	/* give up and parse /proc/mounts */
+	fp = fopen("/proc/mounts", "r");
+	if (fp == NULL)
+		die("Can't open /proc/mounts for read");
+
+	while (fscanf(fp, "%*s %"
+		      STR(MAX_PATH)
+		      "s %99s %*s %*d %*d\n",
+		      debugfs_mountpoint, type) == 2) {
+		if (strcmp(type, "debugfs") == 0)
+			break;
+	}
+	fclose(fp);
+
+	if (strcmp(type, "debugfs") != 0)
+		return NULL;
+
+	debugfs_found = 1;
+
+	return debugfs_mountpoint;
+}
+
+/* verify that a mountpoint is actually a debugfs instance */
+
+int
+debugfs_valid_mountpoint(const char *debugfs)
+{
+	struct statfs st_fs;
+
+	if (statfs(debugfs, &st_fs) < 0)
+		return -ENOENT;
+	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+		return -ENOENT;
+	return 0;
+}
+
+
+int
+debugfs_valid_entry(const char *path)
+{
+	struct stat st;
+
+	if (stat(path, &st))
+		return -errno;
+	return 0;
+}
+
+/* mount the debugfs somewhere */
+
+int
+debugfs_mount(const char *mountpoint)
+{
+	char mountcmd[128];
+
+	/* see if it's already mounted */
+	if (debugfs_find_mountpoint()) {
+		debugfs_premounted = 1;
+		return 0;
+	}
+
+	/* if not mounted and no argument */
+	if (mountpoint == NULL) {
+		/* see if environment variable set */
+		mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
+		/* if no environment variable, use default */
+		if (mountpoint == NULL)
+			mountpoint = "/sys/kernel/debug";
+	}
+
+	/* save the mountpoint */
+	strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
+
+	/* mount it */
+	snprintf(mountcmd, sizeof(mountcmd),
+		 "/bin/mount -t debugfs debugfs %s", mountpoint);
+	return system(mountcmd);
+}
+
+/* umount the debugfs */
+
+int
+debugfs_umount(void)
+{
+	int ret;
+	char umountcmd[128];
+
+	/* if it was already mounted, leave it */
+	if (debugfs_premounted)
+		return 0;
+
+	/* make sure it's a valid mount point */
+	ret = debugfs_valid_mountpoint(debugfs_mountpoint);
+	if (ret)
+		return ret;
+
+	snprintf(umountcmd, sizeof(umountcmd),
+		 "/bin/umount %s", debugfs_mountpoint);
+	return system(umountcmd);
+}
+
+
+int
+debugfs_write(const char *entry, const char *value)
+{
+	int ret, count;
+	int fd;
+	char path[MAX_PATH+1];
+
+	/* construct the path */
+	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+	/* verify that it exists */
+	ret = debugfs_valid_entry(path);
+	if (ret)
+		return ret;
+
+	/* get how many chars we're going to write */
+	count = strlen(value);
+
+	/* open the debugfs entry */
+	fd = open(path, O_RDWR);
+	if (fd < 0)
+		return -errno;
+
+	while (count > 0) {
+		/* write it */
+		ret = write(fd, value, count);
+		if (ret <= 0) {
+			if (ret == EAGAIN)
+				continue;
+			close(fd);
+			return -errno;
+		}
+		count -= ret;
+	}
+
+	/* close it */
+	close(fd);
+
+	/* return success */
+	return 0;
+}
+
+/*
+ * read a debugfs entry
+ * returns the number of chars read or a negative errno
+ */
+
+int
+debugfs_read(const char *entry, char *buffer, size_t size)
+{
+	int ret;
+	int fd;
+	char path[MAX_PATH+1];
+
+	/* construct the path */
+	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+	/* verify that it exists */
+	ret = debugfs_valid_entry(path);
+	if (ret)
+		return ret;
+
+	/* open the debugfs entry */
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	do {
+		/* read it */
+		ret = read(fd, buffer, size);
+		if (ret == 0) {
+			close(fd);
+			return EOF;
+		}
+	} while (ret < 0 && errno == EAGAIN);
+
+	/* close it */
+	close(fd);
+
+	/* make *sure* there's a null character at the end */
+	buffer[ret] = '\0';
+
+	/* return the number of chars read */
+	return ret;
+}
diff --git a/tools/perf/util/debugfs.h b/tools/perf/util/debugfs.h
new file mode 100644
index 0000000..df14c2a
--- /dev/null
+++ b/tools/perf/util/debugfs.h
@@ -0,1 +1,22 @@
+#ifndef __DEBUGFS_H__
+#define __DEBUGFS_H__
+#include <sys/mount.h>
+#ifndef MAX_PATH
+#define MAX_PATH 256
+#endif
+
+#ifndef STR
+#define _STR(x) #x
+#define STR(x) _STR(x)
+#endif
+
+extern const char *debugfs_find_mountpoint(void);
+extern int debugfs_valid_mountpoint(const char *debugfs);
+extern int debugfs_valid_entry(const char *path);
+extern int debugfs_mount(const char *mountpoint);
+extern int debugfs_umount(void);
+extern int debugfs_write(const char *entry, const char *value);
+extern int debugfs_read(const char *entry, char *buffer, size_t size);
+extern void debugfs_force_cleanup(void);
+extern int debugfs_make_path(const char *element, char *buffer, int size);
+#endif
-- 
1.6.2.5


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[PATCH 2/2] modify perf routines to use new debugfs routines

[Clark Williams]

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modified perf.c get_debugfs_mntpnt() to use the util/debugfs.c
debugfs_find_mountpoint()
modified util/parse-events.c to use debugfs_valid_mountpoint().

Signed-off-by: Clark Williams <williams@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/perf.c              |   45 ++++++---------------------------------
 tools/perf/util/parse-events.c |   17 +++-----------
 2 files changed, 11 insertions(+), 51 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 9cafe54..940cbf6 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -14,6 +14,7 @@
 #include "util/run-command.h"
 #include "util/parse-events.h"
 #include "util/string.h"
+#include "util/debugfs.h"
 
 const char perf_usage_string[] =
 	"perf [--version] [--help] COMMAND [ARGS]";
@@ -296,6 +297,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
 		{ "probe", cmd_probe, 0 },
+		{ "latency", cmd_latency, 0},
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
@@ -383,45 +385,12 @@ static int run_argv(int *argcp, const char ***argv)
 /* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
 static void get_debugfs_mntpt(void)
 {
-	FILE *file;
-	char fs_type[100];
-	char debugfs[MAXPATHLEN];
+	const char *path = debugfs_find_mountpoint();
 
-	/*
-	 * try the standard location
-	 */
-	if (valid_debugfs_mount("/sys/kernel/debug/") == 0) {
-		strcpy(debugfs_mntpt, "/sys/kernel/debug/");
-		return;
-	}
-
-	/*
-	 * try the sane location
-	 */
-	if (valid_debugfs_mount("/debug/") == 0) {
-		strcpy(debugfs_mntpt, "/debug/");
-		return;
-	}
-
-	/*
-	 * give up and parse /proc/mounts
-	 */
-	file = fopen("/proc/mounts", "r");
-	if (file == NULL)
-		return;
-
-	while (fscanf(file, "%*s %"
-		      STR(MAXPATHLEN)
-		      "s %99s %*s %*d %*d\n",
-		      debugfs, fs_type) == 2) {
-		if (strcmp(fs_type, "debugfs") == 0)
-			break;
-	}
-	fclose(file);
-	if (strcmp(fs_type, "debugfs") == 0) {
-		strncpy(debugfs_mntpt, debugfs, MAXPATHLEN);
-		debugfs_mntpt[MAXPATHLEN - 1] = '\0';
-	}
+	if (path)
+		strncpy(debugfs_mntpt, path, sizeof(debugfs_mntpt));
+	else
+		debugfs_mntpt[0] = '\0';
 }
 
 int main(int argc, const char **argv)
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 31baa5a..097938a 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -7,6 +7,7 @@
 #include "string.h"
 #include "cache.h"
 #include "header.h"
+#include "debugfs.h"
 
 int				nr_counters;
 
@@ -149,16 +150,6 @@ static int tp_event_has_id(struct dirent *sys_dir, struct dirent *evt_dir)
 
 #define MAX_EVENT_LENGTH 512
 
-int valid_debugfs_mount(const char *debugfs)
-{
-	struct statfs st_fs;
-
-	if (statfs(debugfs, &st_fs) < 0)
-		return -ENOENT;
-	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
-		return -ENOENT;
-	return 0;
-}
 
 struct tracepoint_path *tracepoint_id_to_path(u64 config)
 {
@@ -171,7 +162,7 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount(debugfs_path))
+	if (debugfs_valid_mountpoint(debugfs_path))
 		return NULL;
 
 	sys_dir = opendir(debugfs_path);
@@ -510,7 +501,7 @@ static enum event_result parse_tracepoint_event(const char **strp,
 	char sys_name[MAX_EVENT_LENGTH];
 	unsigned int sys_length, evt_length;
 
-	if (valid_debugfs_mount(debugfs_path))
+	if (debugfs_valid_mountpoint(debugfs_path))
 		return 0;
 
 	evt_name = strchr(*strp, ':');
@@ -788,7 +779,7 @@ static void print_tracepoint_events(void)
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
 
-	if (valid_debugfs_mount(debugfs_path))
+	if (debugfs_valid_mountpoint(debugfs_path))
 		return;
 
 	sys_dir = opendir(debugfs_path);
-- 
1.6.2.5


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