linux-imx

/*

 * dcookies.c

 *

 * Copyright 2002 John Levon <levon@movementarian.org>

 *

 * Persistent cookie-path mappings. These are used by

 * profilers to convert a per-task EIP value into something

 * non-transitory that can be processed at a later date.

 * This is done by locking the dentry/vfsmnt pair in the

 * kernel until released by the tasks needing the persistent

 * objects. The tag is simply an unsigned long that refers

 * to the pair and can be looked up from userspace.

 */

​

#include <linux/syscalls.h>

#include <linux/export.h>

#include <linux/slab.h>

#include <linux/list.h>

#include <linux/mount.h>

#include <linux/capability.h>

#include <linux/dcache.h>

#include <linux/mm.h>

#include <linux/err.h>

#include <linux/errno.h>

#include <linux/dcookies.h>

#include <linux/mutex.h>

#include <linux/path.h>

#include <linux/compat.h>

#include <linux/uaccess.h>

​

/* The dcookies are allocated from a kmem_cache and

 * hashed onto a small number of lists. None of the

 * code here is particularly performance critical

 */

struct dcookie_struct {

    struct path path;

    struct list_head hash_list;

};

​

static LIST_HEAD(dcookie_users);

static DEFINE_MUTEX(dcookie_mutex);

static struct kmem_cache *dcookie_cache __read_mostly;

static struct list_head *dcookie_hashtable __read_mostly;

static size_t hash_size __read_mostly;

​

static inline int is_live(void)

{

    return !(list_empty(&dcookie_users));

}

​

​

/* The dentry is locked, its address will do for the cookie */

static inline unsigned long dcookie_value(struct dcookie_struct * dcs)

{

    return (unsigned long)dcs->path.dentry;

}

​

​

static size_t dcookie_hash(unsigned long dcookie)

{

    return (dcookie >> L1_CACHE_SHIFT) & (hash_size - 1);

}

​

​

static struct dcookie_struct * find_dcookie(unsigned long dcookie)

{

    struct dcookie_struct *found = NULL;

    struct dcookie_struct * dcs;

    struct list_head * pos;

    struct list_head * list;

​

    list = dcookie_hashtable + dcookie_hash(dcookie);

​

    list_for_each(pos, list) {

        dcs = list_entry(pos, struct dcookie_struct, hash_list);

        if (dcookie_value(dcs) == dcookie) {

            found = dcs;

            break;

        }

    }

​

    return found;

}

​

​

static void hash_dcookie(struct dcookie_struct * dcs)

{

    struct list_head * list = dcookie_hashtable + dcookie_hash(dcookie_value(dcs));

    list_add(&dcs->hash_list, list);

}

​

​