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perf tools: Add debugfs utility routines for perf
Add routines to locate the debugfs mount point and to manage the mounting and unmounting of the debugfs. Signed-off-by: Clark Williams <williams@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20091101155621.2b3503ee@torg> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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3 changed files with 268 additions and 0 deletions
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@ -353,6 +353,7 @@ LIB_H += util/include/asm/swab.h
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LIB_H += util/include/asm/system.h
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LIB_H += util/include/asm/uaccess.h
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LIB_H += perf.h
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LIB_H += util/debugfs.h
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LIB_H += util/event.h
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LIB_H += util/types.h
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LIB_H += util/levenshtein.h
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@ -378,6 +379,7 @@ LIB_OBJS += util/abspath.o
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LIB_OBJS += util/alias.o
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LIB_OBJS += util/config.o
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LIB_OBJS += util/ctype.o
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LIB_OBJS += util/debugfs.o
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LIB_OBJS += util/environment.o
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LIB_OBJS += util/event.o
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LIB_OBJS += util/exec_cmd.o
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241
tools/perf/util/debugfs.c
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241
tools/perf/util/debugfs.c
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@ -0,0 +1,241 @@
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#include "util.h"
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#include "debugfs.h"
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#include "cache.h"
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static int debugfs_premounted;
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static char debugfs_mountpoint[MAX_PATH+1];
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static const char *debugfs_known_mountpoints[] = {
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"/sys/kernel/debug/",
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"/debug/",
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0,
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};
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/* use this to force a umount */
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void debugfs_force_cleanup(void)
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{
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debugfs_find_mountpoint();
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debugfs_premounted = 0;
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debugfs_umount();
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}
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/* construct a full path to a debugfs element */
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int debugfs_make_path(const char *element, char *buffer, int size)
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{
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int len;
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if (strlen(debugfs_mountpoint) == 0) {
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buffer[0] = '\0';
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return -1;
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}
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len = strlen(debugfs_mountpoint) + strlen(element) + 1;
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if (len >= size)
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return len+1;
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snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
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return 0;
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}
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static int debugfs_found;
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/* find the path to the mounted debugfs */
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const char *debugfs_find_mountpoint(void)
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{
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const char **ptr;
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char type[100];
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FILE *fp;
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if (debugfs_found)
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return (const char *) debugfs_mountpoint;
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ptr = debugfs_known_mountpoints;
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while (*ptr) {
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if (debugfs_valid_mountpoint(*ptr) == 0) {
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debugfs_found = 1;
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strcpy(debugfs_mountpoint, *ptr);
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return debugfs_mountpoint;
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}
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ptr++;
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}
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/* give up and parse /proc/mounts */
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fp = fopen("/proc/mounts", "r");
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if (fp == NULL)
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die("Can't open /proc/mounts for read");
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while (fscanf(fp, "%*s %"
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STR(MAX_PATH)
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"s %99s %*s %*d %*d\n",
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debugfs_mountpoint, type) == 2) {
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if (strcmp(type, "debugfs") == 0)
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break;
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}
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fclose(fp);
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if (strcmp(type, "debugfs") != 0)
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return NULL;
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debugfs_found = 1;
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return debugfs_mountpoint;
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}
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/* verify that a mountpoint is actually a debugfs instance */
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int debugfs_valid_mountpoint(const char *debugfs)
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{
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struct statfs st_fs;
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if (statfs(debugfs, &st_fs) < 0)
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return -ENOENT;
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else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
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return -ENOENT;
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return 0;
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}
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int debugfs_valid_entry(const char *path)
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{
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struct stat st;
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if (stat(path, &st))
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return -errno;
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return 0;
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}
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/* mount the debugfs somewhere */
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int debugfs_mount(const char *mountpoint)
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{
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char mountcmd[128];
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/* see if it's already mounted */
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if (debugfs_find_mountpoint()) {
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debugfs_premounted = 1;
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return 0;
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}
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/* if not mounted and no argument */
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if (mountpoint == NULL) {
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/* see if environment variable set */
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mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
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/* if no environment variable, use default */
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if (mountpoint == NULL)
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mountpoint = "/sys/kernel/debug";
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}
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/* save the mountpoint */
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strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
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/* mount it */
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snprintf(mountcmd, sizeof(mountcmd),
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"/bin/mount -t debugfs debugfs %s", mountpoint);
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return system(mountcmd);
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}
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/* umount the debugfs */
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int debugfs_umount(void)
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{
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char umountcmd[128];
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int ret;
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/* if it was already mounted, leave it */
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if (debugfs_premounted)
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return 0;
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/* make sure it's a valid mount point */
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ret = debugfs_valid_mountpoint(debugfs_mountpoint);
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if (ret)
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return ret;
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snprintf(umountcmd, sizeof(umountcmd),
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"/bin/umount %s", debugfs_mountpoint);
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return system(umountcmd);
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}
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int debugfs_write(const char *entry, const char *value)
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{
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char path[MAX_PATH+1];
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int ret, count;
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int fd;
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/* construct the path */
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snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
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/* verify that it exists */
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ret = debugfs_valid_entry(path);
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if (ret)
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return ret;
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/* get how many chars we're going to write */
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count = strlen(value);
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/* open the debugfs entry */
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fd = open(path, O_RDWR);
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if (fd < 0)
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return -errno;
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while (count > 0) {
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/* write it */
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ret = write(fd, value, count);
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if (ret <= 0) {
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if (ret == EAGAIN)
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continue;
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close(fd);
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return -errno;
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}
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count -= ret;
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}
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/* close it */
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close(fd);
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/* return success */
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return 0;
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}
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/*
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* read a debugfs entry
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* returns the number of chars read or a negative errno
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*/
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int debugfs_read(const char *entry, char *buffer, size_t size)
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{
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char path[MAX_PATH+1];
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int ret;
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int fd;
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/* construct the path */
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snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
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/* verify that it exists */
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ret = debugfs_valid_entry(path);
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if (ret)
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return ret;
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/* open the debugfs entry */
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fd = open(path, O_RDONLY);
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if (fd < 0)
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return -errno;
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do {
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/* read it */
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ret = read(fd, buffer, size);
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if (ret == 0) {
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close(fd);
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return EOF;
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}
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} while (ret < 0 && errno == EAGAIN);
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/* close it */
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close(fd);
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/* make *sure* there's a null character at the end */
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buffer[ret] = '\0';
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/* return the number of chars read */
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return ret;
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}
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25
tools/perf/util/debugfs.h
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25
tools/perf/util/debugfs.h
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#ifndef __DEBUGFS_H__
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#define __DEBUGFS_H__
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#include <sys/mount.h>
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#ifndef MAX_PATH
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# define MAX_PATH 256
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#endif
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#ifndef STR
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# define _STR(x) #x
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# define STR(x) _STR(x)
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#endif
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extern const char *debugfs_find_mountpoint(void);
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extern int debugfs_valid_mountpoint(const char *debugfs);
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extern int debugfs_valid_entry(const char *path);
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extern int debugfs_mount(const char *mountpoint);
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extern int debugfs_umount(void);
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extern int debugfs_write(const char *entry, const char *value);
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extern int debugfs_read(const char *entry, char *buffer, size_t size);
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extern void debugfs_force_cleanup(void);
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extern int debugfs_make_path(const char *element, char *buffer, int size);
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#endif /* __DEBUGFS_H__ */
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