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Commit afe61f67 authored by Clark Williams's avatar Clark Williams Committed by Ingo Molnar
Browse files

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: default avatarClark 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: default avatarIngo Molnar <mingo@elte.hu>
parent 8d06367f

tools/perf/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -353,6 +353,7 @@ LIB_H += util/include/asm/swab.h 
LIB_H += util/include/asm/system.h

LIB_H += util/include/asm/uaccess.h

LIB_H += perf.h

LIB_H += util/debugfs.h

LIB_H += util/event.h

LIB_H += util/types.h

LIB_H += util/levenshtein.h
@@ -378,6 +379,7 @@ LIB_OBJS += util/abspath.o 
LIB_OBJS += util/alias.o

LIB_OBJS += util/config.o

LIB_OBJS += util/ctype.o

LIB_OBJS += util/debugfs.o

LIB_OBJS += util/environment.o

LIB_OBJS += util/event.o

LIB_OBJS += util/exec_cmd.o

tools/perf/util/debugfs.c

0 → 100644
+241 −0
Original line number Diff line number Diff line 
#include "util.h"

#include "debugfs.h"

#include "cache.h"



static int debugfs_premounted;

static char debugfs_mountpoint[MAX_PATH+1];



static const char *debugfs_known_mountpoints[] = {

	"/sys/kernel/debug/",

	"/debug/",

	0,

};



/* use this to force a umount */

void debugfs_force_cleanup(void)

{

	debugfs_find_mountpoint();

	debugfs_premounted = 0;

	debugfs_umount();

}



/* construct a full path to a debugfs element */

int debugfs_make_path(const char *element, char *buffer, int size)

{

	int len;



	if (strlen(debugfs_mountpoint) == 0) {

		buffer[0] = '\0';

		return -1;

	}



	len = strlen(debugfs_mountpoint) + strlen(element) + 1;

	if (len >= size)

		return len+1;



	snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);

	return 0;

}



static int debugfs_found;



/* find the path to the mounted debugfs */

const char *debugfs_find_mountpoint(void)

{

	const char **ptr;

	char type[100];

	FILE *fp;



	if (debugfs_found)

		return (const char *) debugfs_mountpoint;



	ptr = debugfs_known_mountpoints;

	while (*ptr) {

		if (debugfs_valid_mountpoint(*ptr) == 0) {

			debugfs_found = 1;

			strcpy(debugfs_mountpoint, *ptr);

			return debugfs_mountpoint;

		}

		ptr++;

	}



	/* give up and parse /proc/mounts */

	fp = fopen("/proc/mounts", "r");

	if (fp == NULL)

		die("Can't open /proc/mounts for read");



	while (fscanf(fp, "%*s %"

		      STR(MAX_PATH)

		      "s %99s %*s %*d %*d\n",

		      debugfs_mountpoint, type) == 2) {

		if (strcmp(type, "debugfs") == 0)

			break;

	}

	fclose(fp);



	if (strcmp(type, "debugfs") != 0)

		return NULL;



	debugfs_found = 1;



	return debugfs_mountpoint;

}



/* verify that a mountpoint is actually a debugfs instance */



int debugfs_valid_mountpoint(const char *debugfs)

{

	struct statfs st_fs;



	if (statfs(debugfs, &st_fs) < 0)

		return -ENOENT;

	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)

		return -ENOENT;



	return 0;

}





int debugfs_valid_entry(const char *path)

{

	struct stat st;



	if (stat(path, &st))

		return -errno;



	return 0;

}



/* mount the debugfs somewhere */



int debugfs_mount(const char *mountpoint)

{

	char mountcmd[128];



	/* see if it's already mounted */

	if (debugfs_find_mountpoint()) {

		debugfs_premounted = 1;

		return 0;

	}



	/* if not mounted and no argument */

	if (mountpoint == NULL) {

		/* see if environment variable set */

		mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);

		/* if no environment variable, use default */

		if (mountpoint == NULL)

			mountpoint = "/sys/kernel/debug";

	}



	/* save the mountpoint */

	strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));



	/* mount it */

	snprintf(mountcmd, sizeof(mountcmd),

		 "/bin/mount -t debugfs debugfs %s", mountpoint);

	return system(mountcmd);

}



/* umount the debugfs */



int debugfs_umount(void)

{

	char umountcmd[128];

	int ret;



	/* if it was already mounted, leave it */

	if (debugfs_premounted)

		return 0;



	/* make sure it's a valid mount point */

	ret = debugfs_valid_mountpoint(debugfs_mountpoint);

	if (ret)

		return ret;



	snprintf(umountcmd, sizeof(umountcmd),

		 "/bin/umount %s", debugfs_mountpoint);

	return system(umountcmd);

}



int debugfs_write(const char *entry, const char *value)

{

	char path[MAX_PATH+1];

	int ret, count;

	int fd;



	/* construct the path */

	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);



	/* verify that it exists */

	ret = debugfs_valid_entry(path);

	if (ret)

		return ret;



	/* get how many chars we're going to write */

	count = strlen(value);



	/* open the debugfs entry */

	fd = open(path, O_RDWR);

	if (fd < 0)

		return -errno;



	while (count > 0) {

		/* write it */

		ret = write(fd, value, count);

		if (ret <= 0) {

			if (ret == EAGAIN)

				continue;

			close(fd);

			return -errno;

		}

		count -= ret;

	}



	/* close it */

	close(fd);



	/* return success */

	return 0;

}



/*

 * read a debugfs entry

 * returns the number of chars read or a negative errno

 */

int debugfs_read(const char *entry, char *buffer, size_t size)

{

	char path[MAX_PATH+1];

	int ret;

	int fd;



	/* construct the path */

	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);



	/* verify that it exists */

	ret = debugfs_valid_entry(path);

	if (ret)

		return ret;



	/* open the debugfs entry */

	fd = open(path, O_RDONLY);

	if (fd < 0)

		return -errno;



	do {

		/* read it */

		ret = read(fd, buffer, size);

		if (ret == 0) {

			close(fd);

			return EOF;

		}

	} while (ret < 0 && errno == EAGAIN);



	/* close it */

	close(fd);



	/* make *sure* there's a null character at the end */

	buffer[ret] = '\0';



	/* return the number of chars read */

	return ret;

}

tools/perf/util/debugfs.h

0 → 100644
+25 −0
Original line number Diff line number Diff line 
#ifndef __DEBUGFS_H__

#define __DEBUGFS_H__



#include <sys/mount.h>



#ifndef MAX_PATH

# define MAX_PATH 256

#endif



#ifndef STR

# define _STR(x) #x

# define STR(x) _STR(x)

#endif



extern const char *debugfs_find_mountpoint(void);

extern int debugfs_valid_mountpoint(const char *debugfs);

extern int debugfs_valid_entry(const char *path);

extern int debugfs_mount(const char *mountpoint);

extern int debugfs_umount(void);

extern int debugfs_write(const char *entry, const char *value);

extern int debugfs_read(const char *entry, char *buffer, size_t size);

extern void debugfs_force_cleanup(void);

extern int debugfs_make_path(const char *element, char *buffer, int size);



#endif /* __DEBUGFS_H__ */