From: Rakesh Pandit <rakesh@tuxera.com>
Date: Fri, 13 Oct 2017 12:45:50 +0000 (+0200)
Subject: lightnvm: prevent target type module removal when in use
X-Git-Tag: v4.19~2212^2~195
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=900148296b78c61aa8c443dc594c0da968c3be53;p=platform%2Fkernel%2Flinux-rpi.git

lightnvm: prevent target type module removal when in use

If target type module e.g. pblk here is unloaded (rmmod) while module
is in use (after creating target) system crashes.  We fix this by
using module API refcnt.

Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index ddae430..60e163b 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -22,6 +22,7 @@
 #include <linux/types.h>
 #include <linux/sem.h>
 #include <linux/bitmap.h>
+#include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/miscdevice.h>
 #include <linux/lightnvm.h>
@@ -316,6 +317,8 @@ static int nvm_create_tgt(struct nvm_dev *dev, struct nvm_ioctl_create *create)
 	list_add_tail(&t->list, &dev->targets);
 	mutex_unlock(&dev->mlock);
 
+	__module_get(tt->owner);
+
 	return 0;
 err_sysfs:
 	if (tt->exit)
@@ -351,6 +354,7 @@ static void __nvm_remove_target(struct nvm_target *t)
 
 	nvm_remove_tgt_dev(t->dev, 1);
 	put_disk(tdisk);
+	module_put(t->type->owner);
 
 	list_del(&t->list);
 	kfree(t);
diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 1b0f612..6df65d1 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -1044,6 +1044,7 @@ static struct nvm_tgt_type tt_pblk = {
 
 	.sysfs_init	= pblk_sysfs_init,
 	.sysfs_exit	= pblk_sysfs_exit,
+	.owner		= THIS_MODULE,
 };
 
 static int __init pblk_module_init(void)
diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
index 7dfa56e..7b80ac9 100644
--- a/include/linux/lightnvm.h
+++ b/include/linux/lightnvm.h
@@ -460,6 +460,7 @@ struct nvm_tgt_type {
 
 	/* For internal use */
 	struct list_head list;
+	struct module *owner;
 };
 
 extern struct nvm_tgt_type *nvm_find_target_type(const char *, int);