eventfs: Warn if an eventfs_inode is freed without is_freed being set

There should never be a case where an evenfs_inode is being freed without
is_freed being set. Add a WARN_ON_ONCE() if it ever happens. That would
mean there was one too many put_ei()s.

Link: https://lore.kernel.org/linux-trace-kernel/20240201161616.843551963@goodmis.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 515fdace1eeaf145a7120ce81af61d547c1f2d11..ca7daee7c8115e342e7f652b144dd6bfa2600d19 100644 (file)
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -73,6 +73,9 @@ enum {
 static void release_ei(struct kref *ref)
 {
        struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref);
+
+       WARN_ON_ONCE(!ei->is_freed);
+
        kfree(ei->entry_attrs);
        kfree_const(ei->name);
        kfree_rcu(ei, rcu);
@@ -84,6 +87,14 @@ static inline void put_ei(struct eventfs_inode *ei)
                kref_put(&ei->kref, release_ei);
 }
 
+static inline void free_ei(struct eventfs_inode *ei)
+{
+       if (ei) {
+               ei->is_freed = 1;
+               put_ei(ei);
+       }
+}
+
 static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei)
 {
        if (ei)
@@ -679,7 +690,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
 
        /* Was the parent freed? */
        if (list_empty(&ei->list)) {
-               put_ei(ei);
+               free_ei(ei);
                ei = NULL;
        }
        return ei;
@@ -770,7 +781,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
        return ei;
 
  fail:
-       put_ei(ei);
+       free_ei(ei);
        tracefs_failed_creating(dentry);
        return ERR_PTR(-ENOMEM);
 }
@@ -801,9 +812,8 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
        list_for_each_entry(ei_child, &ei->children, list)
                eventfs_remove_rec(ei_child, level + 1);
 
-       ei->is_freed = 1;
        list_del(&ei->list);
-       put_ei(ei);
+       free_ei(ei);
 }
 
 /**