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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 <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolai Stange 2017-10-31 00:15:53 +01:00 committed by Greg Kroah-Hartman
parent c9afbec270
commit 154b9d7512
1 changed files with 4 additions and 3 deletions
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7
fs/debugfs/file.c
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@ -144,13 +144,13 @@ const struct file_operations debugfs_open_proxy_file_operations = {
static ret_type full_proxy_ ## name(proto) \ static ret_type full_proxy_ ## name(proto) \
{ \ { \
struct dentry *dentry = F_DENTRY(filp); \ struct dentry *dentry = F_DENTRY(filp); \
const struct file_operations *real_fops = \ const struct file_operations *real_fops; \
debugfs_real_fops(filp); \
ret_type r; \ ret_type r; \
\ \
r = debugfs_file_get(dentry); \ r = debugfs_file_get(dentry); \
if (unlikely(r)) \ if (unlikely(r)) \
return r; \ return r; \
real_fops = debugfs_real_fops(filp); \
r = real_fops->name(args); \ r = real_fops->name(args); \
debugfs_file_put(dentry); \ debugfs_file_put(dentry); \
return r; \ return r; \
@ -177,13 +177,14 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, filp,
static unsigned int full_proxy_poll(struct file *filp, static unsigned int full_proxy_poll(struct file *filp,
struct poll_table_struct *wait) struct poll_table_struct *wait)
{ {
const struct file_operations *real_fops = debugfs_real_fops(filp);
struct dentry *dentry = F_DENTRY(filp); struct dentry *dentry = F_DENTRY(filp);
unsigned int r = 0; unsigned int r = 0;
const struct file_operations *real_fops;
if (debugfs_file_get(dentry)) if (debugfs_file_get(dentry))
return POLLHUP; return POLLHUP;
real_fops = debugfs_real_fops(filp);
r = real_fops->poll(filp, wait); r = real_fops->poll(filp, wait);
debugfs_file_put(dentry); debugfs_file_put(dentry);
return r; return r;