Commit 4ef92c2e authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Arnaldo Carvalho de Melo

tools lib api fs: Add tracefs mount helper functions

Since tracefs will now hold the event directory for perf, and even
though by default, debugfs still mounts tracefs on the debugfs/tracing
directory, the system admin may now choose to not mount debugfs and
instead just mount tracefs instead.

Having tracefs helper functions will facilitate having perf look for
tracefs first, and then try debugfs as a fallback.
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150202193552.898934751@goodmis.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent cde164ae
...@@ -9,12 +9,14 @@ LIB_H= ...@@ -9,12 +9,14 @@ LIB_H=
LIB_OBJS= LIB_OBJS=
LIB_H += fs/debugfs.h LIB_H += fs/debugfs.h
LIB_H += fs/tracefs.h
LIB_H += fs/findfs.h LIB_H += fs/findfs.h
LIB_H += fs/fs.h LIB_H += fs/fs.h
# See comment below about piggybacking... # See comment below about piggybacking...
LIB_H += fd/array.h LIB_H += fd/array.h
LIB_OBJS += $(OUTPUT)fs/debugfs.o LIB_OBJS += $(OUTPUT)fs/debugfs.o
LIB_OBJS += $(OUTPUT)fs/tracefs.o
LIB_OBJS += $(OUTPUT)fs/findfs.o LIB_OBJS += $(OUTPUT)fs/findfs.o
LIB_OBJS += $(OUTPUT)fs/fs.o LIB_OBJS += $(OUTPUT)fs/fs.o
# XXX piggybacking here, need to introduce libapikfd, or rename this # XXX piggybacking here, need to introduce libapikfd, or rename this
......
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <sys/vfs.h>
#include <sys/mount.h>
#include <linux/kernel.h>
#include "tracefs.h"
#ifndef TRACEFS_DEFAULT_PATH
#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
#endif
char tracefs_mountpoint[PATH_MAX + 1] = TRACEFS_DEFAULT_PATH;
static const char * const tracefs_known_mountpoints[] = {
TRACEFS_DEFAULT_PATH,
"/sys/kernel/debug/tracing",
"/tracing",
"/trace",
0,
};
static bool tracefs_found;
/* find the path to the mounted tracefs */
const char *tracefs_find_mountpoint(void)
{
const char *ret;
if (tracefs_found)
return (const char *)tracefs_mountpoint;
ret = find_mountpoint("tracefs", (long) TRACEFS_MAGIC,
tracefs_mountpoint, PATH_MAX + 1,
tracefs_known_mountpoints);
if (ret)
tracefs_found = true;
return ret;
}
/* mount the tracefs somewhere if it's not mounted */
char *tracefs_mount(const char *mountpoint)
{
/* see if it's already mounted */
if (tracefs_find_mountpoint())
goto out;
/* if not mounted and no argument */
if (mountpoint == NULL) {
/* see if environment variable set */
mountpoint = getenv(PERF_TRACEFS_ENVIRONMENT);
/* if no environment variable, use default */
if (mountpoint == NULL)
mountpoint = TRACEFS_DEFAULT_PATH;
}
if (mount(NULL, mountpoint, "tracefs", 0, NULL) < 0)
return NULL;
/* save the mountpoint */
tracefs_found = true;
strncpy(tracefs_mountpoint, mountpoint, sizeof(tracefs_mountpoint));
out:
return tracefs_mountpoint;
}
#ifndef __API_TRACEFS_H__
#define __API_TRACEFS_H__
#include "findfs.h"
#ifndef TRACEFS_MAGIC
#define TRACEFS_MAGIC 0x74726163
#endif
#ifndef PERF_TRACEFS_ENVIRONMENT
#define PERF_TRACEFS_ENVIRONMENT "PERF_TRACEFS_DIR"
#endif
const char *tracefs_find_mountpoint(void);
int tracefs_valid_mountpoint(const char *debugfs);
char *tracefs_mount(const char *mountpoint);
extern char tracefs_mountpoint[];
#endif /* __API_DEBUGFS_H__ */
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