From: yu kuai <yukuai3@huawei.com>
To: <gregkh@linuxfoundation.org>, <rafael@kernel.org>,
<viro@zeniv.linux.org.uk>, <rostedt@goodmis.org>,
<oleg@redhat.com>, <mchehab+samsung@kernel.org>, <corbet@lwn.net>,
<tytso@mit.edu>, <jmorris@namei.org>
Cc: <yukuai3@huawei.com>, <linux-kernel@vger.kernel.org>,
<linux-fsdevel@vger.kernel.org>, <zhengbin13@huawei.com>,
<yi.zhang@huawei.com>, <chenxiang66@hisilicon.com>,
<xiexiuqi@huawei.com>
Subject: [PATCH 2/3] fs/libfs.c: use 'spin_lock_nested' when taking 'd_lock' for dentry in simple_empty
Date: Fri, 15 Nov 2019 11:27:51 +0800 [thread overview]
Message-ID: <1573788472-87426-3-git-send-email-yukuai3@huawei.com> (raw)
In-Reply-To: <1573788472-87426-1-git-send-email-yukuai3@huawei.com>
simple_emtpty currently use 'spin_lock_nested' for 'child' to avoid
confusion for lockdep. However, it's not used for 'dentry'.
In that case, there will be a problem if the caller called 'simple_empty'
with a parent's 'd_lock' held:
spin_lock(&dentry->d_parent->d_lock)
call simple_empty(dentry)
spin_lock(&dentry->d_lock) --> lockdep will report this
spin_lock_nested(child->d_lock, spin_lock_nested)
spin_unlock(child_lock)
spin_unlock($dentry->d_lock)
return from simple_empty
spin_unlock(&dentry->d_patrent->d_lock)
So, use 'DENTRY_D_LOCK_NESTED' for 'dentry' and 'spin_lock_nested_2' for
child.
Signed-off-by: yu kuai <yukuai3@huawei.com>
---
fs/libfs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index 1463b03..62e9ba9 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -336,9 +336,9 @@ int simple_empty(struct dentry *dentry)
struct dentry *child;
int ret = 0;
- spin_lock(&dentry->d_lock);
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
list_for_each_entry(child, &dentry->d_subdirs, d_child) {
- spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
+ spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED_2);
if (simple_positive(child)) {
spin_unlock(&child->d_lock);
goto out;
--
2.7.4
next prev parent reply other threads:[~2019-11-15 3:20 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 3:27 [PATCH 0/3] fix potential infinite loop in debugfs_remove_recursive yu kuai
2019-11-15 3:27 ` [PATCH 1/3] dcache: add a new enum type for 'dentry_d_lock_class' yu kuai
2019-11-15 3:27 ` Greg KH
2019-11-15 4:12 ` Al Viro
2019-11-15 7:20 ` Greg KH
2019-11-15 10:08 ` yukuai (C)
2019-11-15 13:16 ` Al Viro
2019-11-15 13:38 ` Steven Rostedt
2019-11-15 13:39 ` Steven Rostedt
2019-11-15 13:48 ` Al Viro
2019-11-15 13:58 ` Steven Rostedt
2019-11-15 14:17 ` Al Viro
2019-11-15 17:54 ` Al Viro
2019-11-15 18:42 ` [RFC] simple_recursive_removal() Al Viro
2019-11-15 19:41 ` Al Viro
2019-11-15 21:18 ` Al Viro
2019-11-15 21:26 ` Steven Rostedt
2019-11-15 22:10 ` Al Viro
2019-11-16 12:04 ` Greg KH
2019-11-17 22:24 ` Al Viro
2019-11-18 6:37 ` Greg KH
2019-11-15 10:02 ` [PATCH 1/3] dcache: add a new enum type for 'dentry_d_lock_class' yukuai (C)
2019-11-15 3:27 ` yu kuai [this message]
2019-11-15 3:27 ` [PATCH 3/3] debugfs: fix potential infinite loop in debugfs_remove_recursive yu kuai
2019-11-30 2:02 [PATCH V2 0/3] " yu kuai
2019-11-30 2:02 ` [PATCH 2/3] fs/libfs.c: use 'spin_lock_nested' when taking 'd_lock' for dentry in simple_empty yu kuai
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