To avoid race conditions, traverse dev, media manager,
and targeet lists and also register, unregister entries
to/from them, should be always under the nvm_lock control.

Signed-off-by: Wenwei Tao <ww.tao0...@gmail.com>
---
 drivers/lightnvm/core.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index f659e60..39aec3a 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -333,19 +333,19 @@ EXPORT_SYMBOL(nvm_register);
 
 void nvm_unregister(char *disk_name)
 {
+       down_write(&nvm_lock);
        struct nvm_dev *dev = nvm_find_nvm_dev(disk_name);
 
        if (!dev) {
                pr_err("nvm: could not find device %s to unregister\n",
                                                                disk_name);
+               up_write(&nvm_lock);
                return;
        }
 
-       nvm_exit(dev);
-
-       down_write(&nvm_lock);
        list_del(&dev->devices);
        up_write(&nvm_lock);
+       nvm_exit(dev);
 }
 EXPORT_SYMBOL(nvm_unregister);
 
@@ -365,12 +365,15 @@ static int nvm_create_target(struct nvm_dev *dev,
        void *targetdata;
        int ret = 0;
 
+       down_write(&nvm_lock);
        if (!dev->mt) {
                /* register with device with a supported NVM manager */
                list_for_each_entry(mt, &nvm_mgrs, list) {
                        ret = mt->register_mgr(dev);
-                       if (ret < 0)
+                       if (ret < 0) {
+                               up_write(&nvm_lock);
                                return ret; /* initialization failed */
+                       }
                        if (ret > 0) {
                                dev->mt = mt;
                                break; /* successfully initialized */
@@ -379,6 +382,7 @@ static int nvm_create_target(struct nvm_dev *dev,
 
                if (!ret) {
                        pr_info("nvm: no compatible nvm manager found.\n");
+                       up_write(&nvm_lock);
                        return -ENODEV;
                }
        }
@@ -386,10 +390,10 @@ static int nvm_create_target(struct nvm_dev *dev,
        tt = nvm_find_target_type(create->tgttype);
        if (!tt) {
                pr_err("nvm: target type %s not found\n", create->tgttype);
+               up_write(&nvm_lock);
                return -EINVAL;
        }
 
-       down_write(&nvm_lock);
        list_for_each_entry(t, &dev->online_targets, list) {
                if (!strcmp(create->tgtname, t->disk->disk_name)) {
                        pr_err("nvm: target name already exists.\n");
@@ -472,8 +476,9 @@ static int __nvm_configure_create(struct nvm_ioctl_create 
*create)
 {
        struct nvm_dev *dev;
        struct nvm_ioctl_create_simple *s;
-
+       down_write(&nvm_lock);
        dev = nvm_find_nvm_dev(create->dev);
+       up_write(&nvm_lock);
        if (!dev) {
                pr_err("nvm: device not found\n");
                return -EINVAL;
@@ -532,7 +537,9 @@ static int nvm_configure_show(const char *val)
                return -EINVAL;
        }
 
+       down_write(&nvm_lock);
        dev = nvm_find_nvm_dev(devname);
+       up_write(&nvm_lock);
        if (!dev) {
                pr_err("nvm: device not found\n");
                return -EINVAL;
-- 
1.9.1

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