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>

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>
Rusty Russell · Eric Lee · Eric Lee · Eric Lee · Eric Lee · Eric Lee
1 parent d8524ae9d6
Showing 2 changed files with 8 additions and 41 deletions Side-by-side Diff
include/linux/module.h
kernel/module.c
@@ -367,9 +367,6 @@
 	/* 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);
  
@@ -644,8 +644,6 @@
  
 	/* 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(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 @@
 /* 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 @@
 		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 @@
  
 	/* 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 @@
 		}
 	}
  
-	/* 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 @@
 		__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();
 	}
 }
...	...	@@ -367,9 +367,6 @@
367	367	/* What modules do I depend on? */
368	368	struct list_head target_list;
369	369
370		- /* Who is waiting for us to be unloaded */
371		- struct task_struct *waiter;
372		-
373	370	/* Destruction function. */
374	371	void (*exit)(void);
375	372
...	...	@@ -644,8 +644,6 @@
644	644
645	645	/* Hold reference count during initialization. */
646	646	__this_cpu_write(mod->refptr->incs, 1);
647		- /* Backwards compatibility macros put refcount during init. */
648		- mod->waiter = current;
649	647
650	648	return 0;
651	649	}
652	650
...	...	@@ -771,16 +769,9 @@
771	769
772	770	static int try_stop_module(struct module mod, int flags, int forced)
773	771	{
774		- if (flags & O_NONBLOCK) {
775		- struct stopref sref = { mod, flags, forced };
	772	+ struct stopref sref = { mod, flags, forced };
776	773
777		- return stop_machine(__try_stop_module, &sref, NULL);
778		- } else {
779		- /* We don't need to stop the machine for this. */
780		- mod->state = MODULE_STATE_GOING;
781		- synchronize_sched();
782		- return 0;
783		- }
	774	+ return stop_machine(__try_stop_module, &sref, NULL);
784	775	}
785	776
786	777	unsigned long module_refcount(struct module *mod)
...	...	@@ -813,21 +804,6 @@
813	804	/* This exists whether we can unload or not */
814	805	static void free_module(struct module *mod);
815	806
816		-static void wait_for_zero_refcount(struct module *mod)
817		-{
818		- /* Since we might sleep for some time, release the mutex first */
819		- mutex_unlock(&module_mutex);
820		- for (;;) {
821		- pr_debug("Looking at refcount...\n");
822		- set_current_state(TASK_UNINTERRUPTIBLE);
823		- if (module_refcount(mod) == 0)
824		- break;
825		- schedule();
826		- }
827		- current->state = TASK_RUNNING;
828		- mutex_lock(&module_mutex);
829		-}
830		-
831	807	SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
832	808	unsigned int, flags)
833	809	{
...	...	@@ -842,6 +818,11 @@
842	818	return -EFAULT;
843	819	name[MODULE_NAME_LEN-1] = '\0';
844	820
	821	+ if (!(flags & O_NONBLOCK)) {
	822	+ printk(KERN_WARNING
	823	+ "waiting module removal not supported: please upgrade");
	824	+ }
	825	+
845	826	if (mutex_lock_interruptible(&module_mutex) != 0)
846	827	return -EINTR;
847	828
...	...	@@ -859,8 +840,7 @@
859	840
860	841	/* Doing init or already dying? */
861	842	if (mod->state != MODULE_STATE_LIVE) {
862		- /* FIXME: if (force), slam module count and wake up
863		- waiter --RR */
	843	+ /* FIXME: if (force), slam module count damn the torpedoes */
864	844	pr_debug("%s already dying\n", mod->name);
865	845	ret = -EBUSY;
866	846	goto out;
867	847
...	...	@@ -876,18 +856,11 @@
876	856	}
877	857	}
878	858
879		- /* Set this up before setting mod->state */
880		- mod->waiter = current;
881		-
882	859	/* Stop the machine so refcounts can't move and disable module. */
883	860	ret = try_stop_module(mod, flags, &forced);
884	861	if (ret != 0)
885	862	goto out;
886	863
887		- /* Never wait if forced. */
888		- if (!forced && module_refcount(mod) != 0)
889		- wait_for_zero_refcount(mod);
890		-
891	864	mutex_unlock(&module_mutex);
892	865	/* Final destruction now no one is using it. */
893	866	if (mod->exit != NULL)
...	...	@@ -1005,9 +978,6 @@
1005	978	__this_cpu_inc(module->refptr->decs);
1006	979
1007	980	trace_module_put(module, _RET_IP_);
1008		- /* Maybe they're waiting for us to drop reference? */
1009		- if (unlikely(!module_is_live(module)))
1010		- wake_up_process(module->waiter);
1011	981	preempt_enable();
1012	982	}
1013	983	}