(2013/07/26 5:04), Oleg Nesterov wrote:
> On 07/25, Oleg Nesterov wrote:
>>
>> To simplify the review, this is how it looks with the patch applied:
>
> v2. We can use simply use list_for_each_entry_safe() and
> list_next_entry() should be calles under ->i_mutex. Although
> debugfs_remove_recursive() can race with itself anyway, but
> still.
>
> And the code looks much simpler. But I do not know what did
> I miss.
>
> Oleg.
>
> void debugfs_remove_recursive(struct dentry *dentry)
> {
> struct dentry *child, *next, *parent;
>
> if (IS_ERR_OR_NULL(dentry))
> return;
>
> parent = dentry->d_parent;
> if (!parent || !parent->d_inode)
> return;
>
> parent = dentry;
> down:
> mutex_lock(&parent->d_inode->i_mutex);
> list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
Perhaps, you can use list_for_each_entry_safe_continue() here, as below.
parent = dentry;
down:
child = list_first_entry_or_null(&parent->d_subdirs,
typeof(*child), d_u.d_child);
mutex_lock(&parent->d_inode->i_mutex);
restart:
list_for_each_entry_safe_continue(child, next, &parent->d_subdirs,
d_u.d_child) {
> if (!debugfs_positive(child))
> continue;
>
> /* XXX: simple_empty(child) instead ? */
> if (!list_empty(&child->d_subdirs)) {
> mutex_unlock(&parent->d_inode->i_mutex);
> parent = child;
> goto down;
> }
> up:
> __debugfs_remove(child, parent);
> }
Then, you can avoid jumping into the loop, just restart it from
parent as below.
mutex_unlock(&parent->d_inode->i_mutex);
child = parent;
parent = parent->d_parent;
mutex_lock(&parent->d_inode->i_mutex);
__debugfs_remove(child, parent);
if (child != dentry)
goto restart;
> mutex_unlock(&parent->d_inode->i_mutex);
> simple_release_fs(&debugfs_mount, &debugfs_mount_count);
> }
It's just an idea, which came up to my mind. :)
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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