+static void helper_unlock(void)
+{
+ if (atomic_dec_and_test(&running_helpers))
+ wake_up(&running_helpers_waitq);
+}
+#else /* CONFIG_PM_SLEEP */
+#define usermodehelper_disabled 0
+
+static inline void helper_lock(void) {}
+static inline void helper_unlock(void) {}
+#endif /* CONFIG_PM_SLEEP */
+
+/**
+ * call_usermodehelper_setup - prepare to call a usermode helper
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @gfp_mask: gfp mask for memory allocation
+ *
+ * Returns either %NULL on allocation failure, or a subprocess_info
+ * structure. This should be passed to call_usermodehelper_exec to
+ * exec the process and free the structure.
+ */
+struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+ char **envp, gfp_t gfp_mask)
+{
+ struct subprocess_info *sub_info;
+ sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
+ if (!sub_info)
+ goto out;
+
+ INIT_WORK(&sub_info->work, __call_usermodehelper);
+ sub_info->path = path;
+ sub_info->argv = argv;
+ sub_info->envp = envp;
+ sub_info->cred = prepare_usermodehelper_creds();
+ if (!sub_info->cred) {
+ kfree(sub_info);
+ return NULL;
+ }
+
+ out:
+ return sub_info;
+}
+EXPORT_SYMBOL(call_usermodehelper_setup);
+
+/**
+ * call_usermodehelper_setkeys - set the session keys for usermode helper
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @session_keyring: the session keyring for the process
+ */
+void call_usermodehelper_setkeys(struct subprocess_info *info,
+ struct key *session_keyring)
+{
+#ifdef CONFIG_KEYS
+ struct thread_group_cred *tgcred = info->cred->tgcred;
+ key_put(tgcred->session_keyring);
+ tgcred->session_keyring = key_get(session_keyring);
+#else
+ BUG();
+#endif
+}
+EXPORT_SYMBOL(call_usermodehelper_setkeys);
+
+/**
+ * call_usermodehelper_setcleanup - set a cleanup function
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @cleanup: a cleanup function
+ *
+ * The cleanup function is just befor ethe subprocess_info is about to
+ * be freed. This can be used for freeing the argv and envp. The
+ * Function must be runnable in either a process context or the
+ * context in which call_usermodehelper_exec is called.
+ */
+void call_usermodehelper_setcleanup(struct subprocess_info *info,
+ void (*cleanup)(char **argv, char **envp))
+{
+ info->cleanup = cleanup;
+}
+EXPORT_SYMBOL(call_usermodehelper_setcleanup);
+
+/**
+ * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin
+ * @sub_info: a subprocess_info returned by call_usermodehelper_setup
+ * @filp: set to the write-end of a pipe
+ *
+ * This constructs a pipe, and sets the read end to be the stdin of the
+ * subprocess, and returns the write-end in *@filp.
+ */
+int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
+ struct file **filp)
+{
+ struct file *f;