module: convert to stop_machine_create/destroy.

The module code relies on a non-failing stop_machine call. So we create
the kstop threads in advance and with that make sure the call won't fail.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 21 insertions, 2 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 4299aefc20b8..f47cce910f25 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -757,8 +757,16 @@ sys_delete_module(const char __user *name_user, unsigned int flags)
                 return -EFAULT;
         name[MODULE_NAME_LEN-1] = '\0';
 
-        if (mutex_lock_interruptible(&module_mutex) != 0)
-                return -EINTR;
+        /* Create stop_machine threads since free_module relies on
+         * a non-failing stop_machine call. */
+        ret = stop_machine_create();
+        if (ret)
+                return ret;
+
+        if (mutex_lock_interruptible(&module_mutex) != 0) {
+                ret = -EINTR;
+                goto out_stop;
+        }
 
         mod = find_module(name);
         if (!mod) {
@@ -817,6 +825,8 @@ sys_delete_module(const char __user *name_user, unsigned int flags)
 
  out:
         mutex_unlock(&module_mutex);
+out_stop:
+        stop_machine_destroy();
         return ret;
 }
 
@@ -1875,6 +1885,13 @@ static noinline struct module *load_module(void __user *umod,
         /* vmalloc barfs on "unusual" numbers.  Check here */
         if (len > 64 * 1024 * 1024 || (hdr = vmalloc(len)) == NULL)
                 return ERR_PTR(-ENOMEM);
+
+        /* Create stop_machine threads since the error path relies on
+         * a non-failing stop_machine call. */
+        err = stop_machine_create();
+        if (err)
+                goto free_hdr;
+
         if (copy_from_user(hdr, umod, len) != 0) {
                 err = -EFAULT;
                 goto free_hdr;
@@ -2258,6 +2275,7 @@ static noinline struct module *load_module(void __user *umod,
         /* Get rid of temporary copy */
         vfree(hdr);
 
+        stop_machine_destroy();
         /* Done! */
         return mod;
 
@@ -2280,6 +2298,7 @@ static noinline struct module *load_module(void __user *umod,
         kfree(args);
  free_hdr:
         vfree(hdr);
+        stop_machine_destroy();
         return ERR_PTR(err);
 
  truncated: