Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#include "util.h"
2#include "debugfs.h"
3#include "cache.h"
4
5#include <linux/kernel.h>
6#include <sys/mount.h>
7
8static int debugfs_premounted;
9char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug";
10char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
11
12static const char *debugfs_known_mountpoints[] = {
13 "/sys/kernel/debug/",
14 "/debug/",
15 0,
16};
17
18static int debugfs_found;
19
20/* find the path to the mounted debugfs */
21const char *debugfs_find_mountpoint(void)
22{
23 const char **ptr;
24 char type[100];
25 FILE *fp;
26
27 if (debugfs_found)
28 return (const char *) debugfs_mountpoint;
29
30 ptr = debugfs_known_mountpoints;
31 while (*ptr) {
32 if (debugfs_valid_mountpoint(*ptr) == 0) {
33 debugfs_found = 1;
34 strcpy(debugfs_mountpoint, *ptr);
35 return debugfs_mountpoint;
36 }
37 ptr++;
38 }
39
40 /* give up and parse /proc/mounts */
41 fp = fopen("/proc/mounts", "r");
42 if (fp == NULL)
43 return NULL;
44
45 while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
46 debugfs_mountpoint, type) == 2) {
47 if (strcmp(type, "debugfs") == 0)
48 break;
49 }
50 fclose(fp);
51
52 if (strcmp(type, "debugfs") != 0)
53 return NULL;
54
55 debugfs_found = 1;
56
57 return debugfs_mountpoint;
58}
59
60/* verify that a mountpoint is actually a debugfs instance */
61
62int debugfs_valid_mountpoint(const char *debugfs)
63{
64 struct statfs st_fs;
65
66 if (statfs(debugfs, &st_fs) < 0)
67 return -ENOENT;
68 else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
69 return -ENOENT;
70
71 return 0;
72}
73
74static void debugfs_set_tracing_events_path(const char *mountpoint)
75{
76 snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s",
77 mountpoint, "tracing/events");
78}
79
80/* mount the debugfs somewhere if it's not mounted */
81
82char *debugfs_mount(const char *mountpoint)
83{
84 /* see if it's already mounted */
85 if (debugfs_find_mountpoint()) {
86 debugfs_premounted = 1;
87 goto out;
88 }
89
90 /* if not mounted and no argument */
91 if (mountpoint == NULL) {
92 /* see if environment variable set */
93 mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
94 /* if no environment variable, use default */
95 if (mountpoint == NULL)
96 mountpoint = "/sys/kernel/debug";
97 }
98
99 if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
100 return NULL;
101
102 /* save the mountpoint */
103 debugfs_found = 1;
104 strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
105out:
106 debugfs_set_tracing_events_path(debugfs_mountpoint);
107 return debugfs_mountpoint;
108}
109
110void debugfs_set_path(const char *mountpoint)
111{
112 snprintf(debugfs_mountpoint, sizeof(debugfs_mountpoint), "%s", mountpoint);
113 debugfs_set_tracing_events_path(mountpoint);
114}