module: remove rmmod --wait option.

The option to wait for a module reference count to reach zero was in
the initial module implementation, but it was never supported in
modprobe (you had to use rmmod --wait).  After discussion with Lucas,
It has been deprecated (with a 10 second sleep) in kmod for the last
year.

This finally removes it: the flag will evoke a printk warning and a
normal (non-blocking) remove attempt.

Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/include/linux/module.h b/include/linux/module.h
index 05f2447f8c15ba5c13b2ec329baf6feaea0b031e..15cd6b1b211e731c5c133dabd0d26e890a56e135 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -367,9 +367,6 @@ struct module
        /* What modules do I depend on? */
        struct list_head target_list;
 
-       /* Who is waiting for us to be unloaded */
-       struct task_struct *waiter;
-
        /* Destruction function. */
        void (*exit)(void);
 

diff --git a/kernel/module.c b/kernel/module.c
index dc582749fa1386db25af23929db4fc20b6c7acce..947105fd4cab8863c23be1714b8c27decb09087b 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -644,8 +644,6 @@ static int module_unload_init(struct module *mod)
 
        /* Hold reference count during initialization. */
        __this_cpu_write(mod->refptr->incs, 1);
-       /* Backwards compatibility macros put refcount during init. */
-       mod->waiter = current;
 
        return 0;
 }
@@ -771,16 +769,9 @@ static int __try_stop_module(void *_sref)
 
 static int try_stop_module(struct module *mod, int flags, int *forced)
 {
-       if (flags & O_NONBLOCK) {
-               struct stopref sref = { mod, flags, forced };
+       struct stopref sref = { mod, flags, forced };
 
-               return stop_machine(__try_stop_module, &sref, NULL);
-       } else {
-               /* We don't need to stop the machine for this. */
-               mod->state = MODULE_STATE_GOING;
-               synchronize_sched();
-               return 0;
-       }
+       return stop_machine(__try_stop_module, &sref, NULL);
 }
 
 unsigned long module_refcount(struct module *mod)
@@ -813,21 +804,6 @@ EXPORT_SYMBOL(module_refcount);
 /* This exists whether we can unload or not */
 static void free_module(struct module *mod);
 
-static void wait_for_zero_refcount(struct module *mod)
-{
-       /* Since we might sleep for some time, release the mutex first */
-       mutex_unlock(&module_mutex);
-       for (;;) {
-               pr_debug("Looking at refcount...\n");
-               set_current_state(TASK_UNINTERRUPTIBLE);
-               if (module_refcount(mod) == 0)
-                       break;
-               schedule();
-       }
-       current->state = TASK_RUNNING;
-       mutex_lock(&module_mutex);
-}
-
 SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                unsigned int, flags)
 {
@@ -842,6 +818,11 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                return -EFAULT;
        name[MODULE_NAME_LEN-1] = '\0';
 
+       if (!(flags & O_NONBLOCK)) {
+               printk(KERN_WARNING
+                      "waiting module removal not supported: please upgrade");
+       }
+
        if (mutex_lock_interruptible(&module_mutex) != 0)
                return -EINTR;
 
@@ -859,8 +840,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
 
        /* Doing init or already dying? */
        if (mod->state != MODULE_STATE_LIVE) {
-               /* FIXME: if (force), slam module count and wake up
-                   waiter --RR */
+               /* FIXME: if (force), slam module count damn the torpedoes */
                pr_debug("%s already dying\n", mod->name);
                ret = -EBUSY;
                goto out;
@@ -876,18 +856,11 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                }
        }
 
-       /* Set this up before setting mod->state */
-       mod->waiter = current;
-
        /* Stop the machine so refcounts can't move and disable module. */
        ret = try_stop_module(mod, flags, &forced);
        if (ret != 0)
                goto out;
 
-       /* Never wait if forced. */
-       if (!forced && module_refcount(mod) != 0)
-               wait_for_zero_refcount(mod);
-
        mutex_unlock(&module_mutex);
        /* Final destruction now no one is using it. */
        if (mod->exit != NULL)
@@ -1005,9 +978,6 @@ void module_put(struct module *module)
                __this_cpu_inc(module->refptr->decs);
 
                trace_module_put(module, _RET_IP_);
-               /* Maybe they're waiting for us to drop reference? */
-               if (unlikely(!module_is_live(module)))
-                       wake_up_process(module->waiter);
                preempt_enable();
        }
 }