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>

1 files changed, 8 insertions, 38 deletions

diff --git a/kernel/module.c b/kernel/module.c
index dc582749fa13..947105fd4cab 100644
--- 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();
         }
 }