module: Remove preempt_disable() from module reference counting.

The preempt_disable() section in module_put() was added in commit
   e1783a2 ("module: Use this_cpu_xx to dynamically allocate counters")

while the per-CPU counter were switched to another API. The API requires
that during the RMW operation the CPU remained the same.

This counting API was later replaced with atomic_t in commit
   2f35c41 ("module: Replace module_ref with atomic_t refcnt")

Since this atomic_t replacement there is no need to keep preemption
disabled while the reference counter is modified.

Remove preempt_disable() from module_put(), __module_get() and
try_module_get().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Author: Sebastian Andrzej Siewior

kernel/module/main.c

@@ -820,10 +820,8 @@ static struct module_attribute modinfo_refcnt =
 void __module_get(struct module *module)
 {
 	if (module) {
-		preempt_disable();
 		atomic_inc(&module->refcnt);
 		trace_module_get(module, _RET_IP_);
-		preempt_enable();
 	}
 }
 EXPORT_SYMBOL(__module_get);
@@ -833,15 +831,12 @@ bool try_module_get(struct module *module)
 	bool ret = true;
 
 	if (module) {
-		preempt_disable();
 		/* Note: here, we can fail to get a reference */
 		if (likely(module_is_live(module) &&
 			   atomic_inc_not_zero(&module->refcnt) != 0))
 			trace_module_get(module, _RET_IP_);
 		else
 			ret = false;
-
-		preempt_enable();
 	}
 	return ret;
 }
@@ -852,11 +847,9 @@ void module_put(struct module *module)
 	int ret;
 
 	if (module) {
-		preempt_disable();
 		ret = atomic_dec_if_positive(&module->refcnt);
 		WARN_ON(ret < 0);	/* Failed to put refcount */
 		trace_module_put(module, _RET_IP_);
-		preempt_enable();
 	}
 }
 EXPORT_SYMBOL(module_put);