From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 23 Jul 2008 00:24:25 +0000 (-0500)
Subject: module: don't use stop_machine for waiting rmmod
X-Git-Tag: firefly_0821_release~19459^2~11
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=da39ba5e1d65e997a98f6eb93ba6e6eb505f6e3c;hp=93ded9b8fd42abe2c3607097963d8de6ad9117eb;p=firefly-linux-kernel-4.4.55.git

module: don't use stop_machine for waiting rmmod

rmmod has a little-used "-w" option, meaning that instead of failing if the
module is in use, it should block until the module becomes unused.

In this case, we don't need to use stop_machine: Max Krasnyansky
indicated that would be useful for SystemTap which loads/unloads new
modules frequently.

Cc: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---

diff --git a/kernel/module.c b/kernel/module.c
index 5f80478b746d..705e1d5d516c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -639,8 +639,8 @@ static int __try_stop_module(void *_sref)
 {
 	struct stopref *sref = _sref;
 
-	/* If it's not unused, quit unless we are told to block. */
-	if ((sref->flags & O_NONBLOCK) && module_refcount(sref->mod) != 0) {
+	/* If it's not unused, quit unless we're forcing. */
+	if (module_refcount(sref->mod) != 0) {
 		if (!(*sref->forced = try_force_unload(sref->flags)))
 			return -EWOULDBLOCK;
 	}
@@ -652,9 +652,16 @@ static int __try_stop_module(void *_sref)
 
 static int try_stop_module(struct module *mod, int flags, int *forced)
 {
-	struct stopref sref = { mod, flags, forced };
+	if (flags & O_NONBLOCK) {
+		struct stopref sref = { mod, flags, forced };
 
-	return stop_machine_run(__try_stop_module, &sref, NR_CPUS);
+		return stop_machine_run(__try_stop_module, &sref, NR_CPUS);
+	} else {
+		/* We don't need to stop the machine for this. */
+		mod->state = MODULE_STATE_GOING;
+		synchronize_sched();
+		return 0;
+	}
 }
 
 unsigned int module_refcount(struct module *mod)