From 4ef92c2ecd96ebad171e554020c83ce9fdb343ae Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 2 Feb 2015 14:35:04 -0500 Subject: 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: Steven Rostedt Acked-by: Jiri Olsa Cc: Andrew Morton Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Namhyung Kim Link: http://lkml.kernel.org/r/20150202193552.898934751@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/tracefs.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 tools/lib/api/fs/tracefs.c (limited to 'tools/lib/api/fs/tracefs.c') diff --git a/tools/lib/api/fs/tracefs.c b/tools/lib/api/fs/tracefs.c new file mode 100644 index 000000000000..ef40d15821e9 --- /dev/null +++ b/tools/lib/api/fs/tracefs.c @@ -0,0 +1,70 @@ +#include +#include +#include +#include +#include +#include +#include +#include + +#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; +} -- cgit From dd6dda27a8be563eaebb3f38b1d1d50920bb7991 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 2 Feb 2015 14:35:06 -0500 Subject: tools lib api fs: Add {tracefs,debugfs}_configured() functions Add tracefs_configured() to return true if tracefs is configured in the kernel (succeeds to find tracefs), and debugfs_configured() if debugfs is configured in the kernel (succeeds to find debugfs). Signed-off-by: Steven Rostedt Acked-by: Jiri Olsa Cc: Andrew Morton Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Namhyung Kim Link: http://lkml.kernel.org/r/20150202193553.190606690@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/tracefs.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'tools/lib/api/fs/tracefs.c') diff --git a/tools/lib/api/fs/tracefs.c b/tools/lib/api/fs/tracefs.c index ef40d15821e9..e4aa9688b71e 100644 --- a/tools/lib/api/fs/tracefs.c +++ b/tools/lib/api/fs/tracefs.c @@ -2,8 +2,11 @@ #include #include #include +#include #include #include +#include +#include #include #include @@ -25,6 +28,11 @@ static const char * const tracefs_known_mountpoints[] = { static bool tracefs_found; +bool tracefs_configured(void) +{ + return tracefs_find_mountpoint() != NULL; +} + /* find the path to the mounted tracefs */ const char *tracefs_find_mountpoint(void) { -- cgit