> diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h
> index 273c59a032512..4035054309d7c 100644
> --- a/include/linux/rcupdate_trace.h
> +++ b/include/linux/rcupdate_trace.h
> @@ -93,22 +93,20 @@ static inline void rcu_read_unlock_tasks_trace(struct
> srcu_ctr __percpu *scp)
> *
> * For more details, please see the documentation for rcu_read_lock().
> */
> -static inline void rcu_read_lock_trace(void)
> +static __always_inline void rcu_read_lock_trace(void)
> {
> int n;
> struct task_struct *t = current;
>
> - rcu_try_lock_acquire(&rcu_tasks_trace_srcu_struct.dep_map);
> n = READ_ONCE(t->trc_reader_nesting);
> WRITE_ONCE(t->trc_reader_nesting, n + 1);
> - if (n) {
> - // In case we interrupted a Tasks Trace RCU reader.
> - return;
> - }
> - barrier(); // nesting before scp to protect against interrupt handler.
> - t->trc_reader_scp = __srcu_read_lock_fast(&rcu_tasks_trace_srcu_struct);
> - if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU_NO_MB))
> - smp_mb(); // Placeholder for more selective ordering
> + if (!n) {
> + barrier(); // nesting before scp to protect against interrupt
> handler.
> + t->trc_reader_scp =
> __srcu_read_lock_fast(&rcu_tasks_trace_srcu_struct);
> + if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU_NO_MB))
> + smp_mb(); // Placeholder for more selective ordering
> + } // Else we interrupted a Tasks Trace RCU reader.
> + rcu_try_lock_acquire(&rcu_tasks_trace_srcu_struct.dep_map);
> }
>
> /**
> @@ -120,12 +118,13 @@ static inline void rcu_read_lock_trace(void)
> *
> * For more details, please see the documentation for rcu_read_unlock().
> */
> -static inline void rcu_read_unlock_trace(void)
> +static __always_inline void rcu_read_unlock_trace(void)
> {
> int n;
> struct srcu_ctr __percpu *scp;
> struct task_struct *t = current;
>
> + srcu_lock_release(&rcu_tasks_trace_srcu_struct.dep_map);
> n = READ_ONCE(t->trc_reader_nesting) - 1;
> if (n) {
> WRITE_ONCE(t->trc_reader_nesting, n);
> @@ -137,7 +136,6 @@ static inline void rcu_read_unlock_trace(void)
> smp_mb(); // Placeholder for more selective ordering
> __srcu_read_unlock_fast(&rcu_tasks_trace_srcu_struct, scp);
> }
> - srcu_lock_release(&rcu_tasks_trace_srcu_struct.dep_map);
> }
This isn't a bug, but the changelog notes that rcu_read_lock_tasks_trace()
already annotates inside the reader "on the lock side" and then says "Make
the trace variants match."
rcu_read_unlock_tasks_trace(), four functions above the changed code in the
same header, still calls srcu_lock_release() after __srcu_read_unlock_fast(),
i.e. the exact ordering being corrected in rcu_read_unlock_trace().
After this patch the two unlock helpers in the file disagree. This has no
functional effect (srcu_lock_release() is a lockdep annotation and compiles
away without CONFIG_DEBUG_LOCK_ALLOC), but would it be worth either flipping
rcu_read_unlock_tasks_trace() the same way, or saying in the changelog why
only the rcu_read_{,un}lock_trace() pair is being changed?
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/34975311706
