Re: [PATH v3] tracing: Fix race condition in kprobe initialization causing NULL pointer dereference
From: John Ogness <john.ogness@linutronix.de>
Date: 2025-09-30 09:14:00
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lkml
On 2025-09-30, chenyuan_fl@163.com wrote:
quoted hunk ↗ jump to hunk
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 842383fbc03b..98b838591edc 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h@@ -274,19 +274,19 @@ struct event_file_link { static inline bool trace_probe_test_flag(struct trace_probe *tp, unsigned int flag) { - return !!(tp->event->flags & flag); + return !!(smp_load_acquire(&tp->event->flags) & flag); } static inline void trace_probe_set_flag(struct trace_probe *tp, unsigned int flag) { - tp->event->flags |= flag; + smp_store_release(&tp->event->flags, tp->event->flags | flag); } static inline void trace_probe_clear_flag(struct trace_probe *tp, unsigned int flag) { - tp->event->flags &= ~flag; + smp_store_release(&tp->event->flags, tp->event->flags & ~flag); } static inline bool trace_probe_is_enabled(struct trace_probe *tp)
I don't have any feedback about the correctness with regards to tracing and kprobes. However, I recommend writing a comment at each necessary memory barrier site. The comment should mention the pairing memory barrier and the ordering it is guaranteeing. John