Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#include <errno.h>
2#include <stdio.h>
3#include <stdlib.h>
4#include <string.h>
5#include <unistd.h>
6#include <stdbool.h>
7#include <sys/vfs.h>
8#include <sys/types.h>
9#include <sys/stat.h>
10#include <sys/mount.h>
11#include <linux/kernel.h>
12
13#include "tracefs.h"
14
15#ifndef TRACEFS_DEFAULT_PATH
16#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
17#endif
18
19char tracefs_mountpoint[PATH_MAX + 1] = TRACEFS_DEFAULT_PATH;
20
21static const char * const tracefs_known_mountpoints[] = {
22 TRACEFS_DEFAULT_PATH,
23 "/sys/kernel/debug/tracing",
24 "/tracing",
25 "/trace",
26 0,
27};
28
29static bool tracefs_found;
30
31bool tracefs_configured(void)
32{
33 return tracefs_find_mountpoint() != NULL;
34}
35
36/* find the path to the mounted tracefs */
37const char *tracefs_find_mountpoint(void)
38{
39 const char *ret;
40
41 if (tracefs_found)
42 return (const char *)tracefs_mountpoint;
43
44 ret = find_mountpoint("tracefs", (long) TRACEFS_MAGIC,
45 tracefs_mountpoint, PATH_MAX + 1,
46 tracefs_known_mountpoints);
47
48 if (ret)
49 tracefs_found = true;
50
51 return ret;
52}
53
54/* mount the tracefs somewhere if it's not mounted */
55char *tracefs_mount(const char *mountpoint)
56{
57 /* see if it's already mounted */
58 if (tracefs_find_mountpoint())
59 goto out;
60
61 /* if not mounted and no argument */
62 if (mountpoint == NULL) {
63 /* see if environment variable set */
64 mountpoint = getenv(PERF_TRACEFS_ENVIRONMENT);
65 /* if no environment variable, use default */
66 if (mountpoint == NULL)
67 mountpoint = TRACEFS_DEFAULT_PATH;
68 }
69
70 if (mount(NULL, mountpoint, "tracefs", 0, NULL) < 0)
71 return NULL;
72
73 /* save the mountpoint */
74 tracefs_found = true;
75 strncpy(tracefs_mountpoint, mountpoint, sizeof(tracefs_mountpoint));
76out:
77 return tracefs_mountpoint;
78}