On 07/26, Oleg Nesterov wrote:
>
> Testing: seems to work, but assumes that debugs was fixed too. Hopefully
> "debugfs: debugfs_remove_recursive() must not rely on list_empty(d_subdirs)"
> is fine.
>
> (We should probably make debugfs_remove_recursive() to return the error
> and trace_events.c should warn if it fails)
>
> However: I am still testing this patches, so this is still mostly for
> review. I'll report if I find anything,
I tried to play more with these patches, and didn't find anything wrong.
However, after I re-read 6/6 I think it should be updated:
- remove_event_file_dir() needs to check file->dir != NULL
it can be NULL if event_create_dir()->debugfs_create_dir()
fails, or if event_create_dir() fails before.
- I've also added spin_lock(d_lock) and d_inode != NULL check.
I do not think this is needed. Afaics __create_file() can't
leave the !debugfs_positive() file on ->d_subdirs list if
debugfs_get_inode() fails, dput()->d_kill() should remove it.
But I do not understand this code enough, and debugfs checks
d_inode != NULL all the time.
I am sending "PATCH v3 6/6" in reply to "PATCH v2 6/6". See the diff
below.
So I am waiting for your review. If you and Masami agree with these
changes I'll resend other fixes (1 from me and 2 from Steven) on top
of this series.
Oleg.
--- x/kernel/trace/trace_events.c
+++ x/kernel/trace/trace_events.c
@@ -431,12 +431,18 @@ static void remove_event_file_dir(struct
struct dentry *dir = file->dir;
struct dentry *child;
- /* ->i_mutex is not needed, nobody can create/remove a file */
- list_for_each_entry(child, &dir->d_subdirs, d_u.d_child)
- child->d_inode->i_private = NULL;
+ if (dir) {
+ spin_lock(&dir->d_lock); /* probably unneeded */
+ list_for_each_entry(child, &dir->d_subdirs, d_u.d_child) {
+ if (child->d_inode) /* probably unneeded */
+ child->d_inode->i_private = NULL;
+ }
+ spin_unlock(&dir->d_lock);
+
+ debugfs_remove_recursive(dir);
+ }
list_del(&file->list);
- debugfs_remove_recursive(dir);
remove_subsystem(file->system);
kmem_cache_free(file_cachep, file);
}
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