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

Steven Rostedt
2024-01-31T21:36:47Z

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

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.

As put_ei() is also called on failure cases to free the ei, add a free_ei()
helper that sets the is_freed and then calls put_ei().

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
fs/tracefs/event_inode.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 31cbe38739fa..463920295237 100644
--- 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)
@@ -684,7 +695,7 @@ 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;
@@ -775,7 +786,7 @@ 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);
}
@@ -806,9 +817,8 @@ 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);
}

/**
--
2.43.0