These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / fs / devpts / inode.c

diff --git a/kernel/fs/devpts/inode.c b/kernel/fs/devpts/inode.c
index add5663..706de32 100644 (file)
--- a/kernel/fs/devpts/inode.c
+++ b/kernel/fs/devpts/inode.c
@@ -142,6 +142,8 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode)
        if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
                return inode->i_sb;
 #endif
+       if (!devpts_mnt)
+               return NULL;
        return devpts_mnt->mnt_sb;
 }
 
@@ -525,10 +527,14 @@ static struct file_system_type devpts_fs_type = {
 int devpts_new_index(struct inode *ptmx_inode)
 {
        struct super_block *sb = pts_sb_from_inode(ptmx_inode);
-       struct pts_fs_info *fsi = DEVPTS_SB(sb);
+       struct pts_fs_info *fsi;
        int index;
        int ida_ret;
 
+       if (!sb)
+               return -ENODEV;
+
+       fsi = DEVPTS_SB(sb);
 retry:
        if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
                return -ENOMEM;
@@ -569,6 +575,26 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx)
        mutex_unlock(&allocated_ptys_lock);
 }
 
+/*
+ * pty code needs to hold extra references in case of last /dev/tty close
+ */
+
+void devpts_add_ref(struct inode *ptmx_inode)
+{
+       struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+
+       atomic_inc(&sb->s_active);
+       ihold(ptmx_inode);
+}
+
+void devpts_del_ref(struct inode *ptmx_inode)
+{
+       struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+
+       iput(ptmx_inode);
+       deactivate_super(sb);
+}
+
 /**
  * devpts_pty_new -- create a new inode in /dev/pts/
  * @ptmx_inode: inode of the master
@@ -584,11 +610,18 @@ struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
        struct dentry *dentry;
        struct super_block *sb = pts_sb_from_inode(ptmx_inode);
        struct inode *inode;
-       struct dentry *root = sb->s_root;
-       struct pts_fs_info *fsi = DEVPTS_SB(sb);
-       struct pts_mount_opts *opts = &fsi->mount_opts;
+       struct dentry *root;
+       struct pts_fs_info *fsi;
+       struct pts_mount_opts *opts;
        char s[12];
 
+       if (!sb)
+               return ERR_PTR(-ENODEV);
+
+       root = sb->s_root;
+       fsi = DEVPTS_SB(sb);
+       opts = &fsi->mount_opts;
+
        inode = new_inode(sb);
        if (!inode)
                return ERR_PTR(-ENOMEM);
@@ -676,12 +709,16 @@ static int __init init_devpts_fs(void)
        struct ctl_table_header *table;
 
        if (!err) {
+               struct vfsmount *mnt;
+
                table = register_sysctl_table(pty_root_table);
-               devpts_mnt = kern_mount(&devpts_fs_type);
-               if (IS_ERR(devpts_mnt)) {
-                       err = PTR_ERR(devpts_mnt);
+               mnt = kern_mount(&devpts_fs_type);
+               if (IS_ERR(mnt)) {
+                       err = PTR_ERR(mnt);
                        unregister_filesystem(&devpts_fs_type);
                        unregister_sysctl_table(table);
+               } else {
+                       devpts_mnt = mnt;
                }
        }
        return err;