From 154b9d7512ae012aca7b4e90af67a72419ad1941 Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Tue, 31 Oct 2017 00:15:53 +0100 Subject: [PATCH] debugfs: call debugfs_real_fops() only after debugfs_file_get() The current implementation of debugfs_real_fops() relies on a debugfs_fsdata instance to be installed at ->d_fsdata. With future patches introducing lazy allocation of these, this requirement will be guaranteed to be fullfilled only inbetween a debugfs_file_get()/debugfs_file_put() pair. The full proxies' fops implemented by debugfs happen to be the only offenders. Fix them up by moving their debugfs_real_fops() calls past those to debugfs_file_get(). full_proxy_release() is special as it doesn't invoke debugfs_file_get() at all. Leave it alone for now. Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/file.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 53f5c9a2af88..bc3549c95574 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -144,13 +144,13 @@ const struct file_operations debugfs_open_proxy_file_operations = { static ret_type full_proxy_ ## name(proto) \ { \ struct dentry *dentry = F_DENTRY(filp); \ - const struct file_operations *real_fops = \ - debugfs_real_fops(filp); \ + const struct file_operations *real_fops; \ ret_type r; \ \ r = debugfs_file_get(dentry); \ if (unlikely(r)) \ return r; \ + real_fops = debugfs_real_fops(filp); \ r = real_fops->name(args); \ debugfs_file_put(dentry); \ return r; \ @@ -177,13 +177,14 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, filp, static unsigned int full_proxy_poll(struct file *filp, struct poll_table_struct *wait) { - const struct file_operations *real_fops = debugfs_real_fops(filp); struct dentry *dentry = F_DENTRY(filp); unsigned int r = 0; + const struct file_operations *real_fops; if (debugfs_file_get(dentry)) return POLLHUP; + real_fops = debugfs_real_fops(filp); r = real_fops->poll(filp, wait); debugfs_file_put(dentry); return r;