From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Add a function that will return where the debugfs file system is mounted
and if it is not mounted it will mount it. This is useful for trace-cmd
as it needs to read the KVM debug offset and multiplier of KVM guests,
and since tracefs_tracing_dir() does the same work to find the tracefs
file system (and may even find where debugfs is), this uses the same
code to accomplish finding the debugfs file system.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
Documentation/libtracefs-files.txt | 11 +++++++++-
include/tracefs-local.h | 2 +-
include/tracefs.h | 1 +
src/tracefs-hist.c | 2 +-
src/tracefs-instance.c | 2 +-
src/tracefs-utils.c | 35 ++++++++++++++++++++++++++----
6 files changed, 45 insertions(+), 8 deletions(-)
diff --git a/Documentation/libtracefs-files.txt b/Documentation/libtracefs-files.txt
index 13e251ddd465..ab917a6ae451 100644
--- a/Documentation/libtracefs-files.txt
+++ b/Documentation/libtracefs-files.txt
@@ -3,7 +3,7 @@ libtracefs(3)
NAME
----
-tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir -
+tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir, tracefs_debug_dir -
Find locations of trace directory and files.
SYNOPSIS
@@ -15,6 +15,7 @@ SYNOPSIS
char pass:[*]*tracefs_get_tracing_file*(const char pass:[*]_name_);
void *tracefs_put_tracing_file*(char pass:[*]_name_);
const char pass:[*]*tracefs_tracing_dir*(void);
+const char pass:[*]*tracefs_debug_dir*(void);
--
DESCRIPTION
@@ -38,6 +39,11 @@ tracing file system is located, cached and returned. It will mount it,
if it is not mounted. On any subsequent call the cached path is returned.
The return string must _not_ be freed.
+The *tracefs_debug_dir()* is similar to *tracefs_tracing_dir()* except
+that it will return where the debugfs file system is mounted. If it
+is not mounted it will try to mount it. The return string must _not_
+be freed.
+
RETURN VALUE
------------
The *tracefs_get_tracing_file()* function returns a string or NULL in case
@@ -46,6 +52,9 @@ of an error. The returned string must be freed with *tracefs_put_tracing_file()*
The *tracefs_tracing_dir()* function returns a constant string or NULL
in case of an error. The returned string must _not_ be freed.
+The *tracefs_debug_dir()* function returns a constant string or NULL
+in case of an error. The returned string must _not_ be freed.
+
EXAMPLE
-------
[source,c]
diff --git a/include/tracefs-local.h b/include/tracefs-local.h
index 926fd02c3d1e..d0ed2abfe5e7 100644
--- a/include/tracefs-local.h
+++ b/include/tracefs-local.h
@@ -50,7 +50,7 @@ void tracefs_warning(const char *fmt, ...);
int str_read_file(const char *file, char **buffer, bool warn);
char *trace_append_file(const char *dir, const char *name);
-char *trace_find_tracing_dir(void);
+char *trace_find_tracing_dir(bool debugfs);
#ifndef ACCESSPERMS
#define ACCESSPERMS (S_IRWXU|S_IRWXG|S_IRWXO) /* 0777 */
diff --git a/include/tracefs.h b/include/tracefs.h
index 27954a41661b..693860d47a56 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -15,6 +15,7 @@ void tracefs_put_tracing_file(char *name);
/* the returned string must *not* be freed */
const char *tracefs_tracing_dir(void);
+const char *tracefs_debug_dir(void);
/* ftrace instances */
struct tracefs_instance;
diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index e688eb3c940c..0d113127def9 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -2194,7 +2194,7 @@ int tracefs_synth_echo_cmd(struct trace_seq *seq,
new_event = true;
}
- path = trace_find_tracing_dir();
+ path = trace_find_tracing_dir(false);
if (!path)
goto out_free;
diff --git a/src/tracefs-instance.c b/src/tracefs-instance.c
index 1493938fa445..249a5c9a3abe 100644
--- a/src/tracefs-instance.c
+++ b/src/tracefs-instance.c
@@ -334,7 +334,7 @@ char *tracefs_instance_get_dir(struct tracefs_instance *instance)
int ret;
if (!instance) /* Top instance of default system trace directory */
- return trace_find_tracing_dir();
+ return trace_find_tracing_dir(false);
if (!instance->name)
return strdup(instance->trace_dir);
diff --git a/src/tracefs-utils.c b/src/tracefs-utils.c
index 7b1f8164d9ab..22f82afe032b 100644
--- a/src/tracefs-utils.c
+++ b/src/tracefs-utils.c
@@ -86,11 +86,12 @@ static int mount_debugfs(void)
/**
* trace_find_tracing_dir - Find tracing directory
+ * @debugfs: Boolean to just return the debugfs directory
*
* Returns string containing the full path to the system's tracing directory.
* The string must be freed by free()
*/
-__hidden char *trace_find_tracing_dir(void)
+__hidden char *trace_find_tracing_dir(bool debugfs)
{
char *debug_str = NULL;
char fspath[PATH_MAX+1];
@@ -109,9 +110,11 @@ __hidden char *trace_find_tracing_dir(void)
STR(PATH_MAX)
"s %99s %*s %*d %*d\n",
fspath, type) == 2) {
- if (strcmp(type, "tracefs") == 0)
+ if (!debugfs && strcmp(type, "tracefs") == 0)
break;
if (!debug_str && strcmp(type, "debugfs") == 0) {
+ if (debugfs)
+ break;
debug_str = strdup(fspath);
if (!debug_str) {
fclose(fp);
@@ -121,7 +124,13 @@ __hidden char *trace_find_tracing_dir(void)
}
fclose(fp);
- if (strcmp(type, "tracefs") != 0) {
+ if (debugfs) {
+ if (strcmp(type, "debugfs") != 0) {
+ if (mount_debugfs() < 0)
+ return NULL;
+ strcpy(fspath, DEBUGFS_PATH);
+ }
+ } else if (strcmp(type, "tracefs") != 0) {
if (mount_tracefs() < 0) {
if (debug_str) {
strncpy(fspath, debug_str, PATH_MAX);
@@ -168,10 +177,28 @@ const char *tracefs_tracing_dir(void)
if (tracing_dir)
return tracing_dir;
- tracing_dir = trace_find_tracing_dir();
+ tracing_dir = trace_find_tracing_dir(false);
return tracing_dir;
}
+/**
+ * tracefs_debug_dir - Get debugfs directory path
+ *
+ * Returns string containing the full path to the system's debugfs directory.
+ *
+ * The returned string must *not* be freed.
+ */
+const char *tracefs_debug_dir(void)
+{
+ static const char *debug_dir;
+
+ if (debug_dir)
+ return debug_dir;
+
+ debug_dir = trace_find_tracing_dir(true);
+ return debug_dir;
+}
+
/**
* tracefs_get_tracing_file - Get tracing file
* @name: tracing file name
--
2.35.1
|