debugfs: call debugfs_real_fops() only after debugfs_file_get() (154b9d75) · Commits · 戴 / test

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>

fs/debugfs/file.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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;

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