Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Cross-merge networking fixes after downstream PR.

No conflicts or adjacent changes.

Link: https://patch.msgid.link/20240808170148.3629934-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 8783bebd0562..bd3e3069300e 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1634,6 +1634,29 @@ static inline void *event_file_data(struct file *filp)
 extern struct mutex event_mutex;
 extern struct list_head ftrace_events;
 
+/*
+ * When the trace_event_file is the filp->i_private pointer,
+ * it must be taken under the event_mutex lock, and then checked
+ * if the EVENT_FILE_FL_FREED flag is set. If it is, then the
+ * data pointed to by the trace_event_file can not be trusted.
+ *
+ * Use the event_file_file() to access the trace_event_file from
+ * the filp the first time under the event_mutex and check for
+ * NULL. If it is needed to be retrieved again and the event_mutex
+ * is still held, then the event_file_data() can be used and it
+ * is guaranteed to be valid.
+ */
+static inline struct trace_event_file *event_file_file(struct file *filp)
+{
+	struct trace_event_file *file;
+
+	lockdep_assert_held(&event_mutex);
+	file = READ_ONCE(file_inode(filp)->i_private);
+	if (!file || file->flags & EVENT_FILE_FL_FREED)
+		return NULL;
+	return file;
+}
+
 extern const struct file_operations event_trigger_fops;
 extern const struct file_operations event_hist_fops;
 extern const struct file_operations event_hist_debug_fops;