From: "Joel Fernandes (Google)" joel@joelfernandes.org
In the last patch in this series, we are making lockdep register hooks onto the irq_{disable,enable} tracepoints. These tracepoints use the _rcuidle tracepoint variant. In this series we switch the _rcuidle tracepoint callers to use SRCU instead of sched-RCU. Inorder to dereference the pointer to the probe functions, we could call srcu_dereference, however this API will call back into lockdep to check if the lock is held *before* the lockdep probe hooks have a chance to run and annotate the IRQ enabled/disabled state.
For this reason we need a notrace variant of srcu_dereference since otherwise we get lockdep splats. This patch adds the needed srcu_dereference_notrace variant.
Reviewed-by: Paul E. McKenney paulmck@linux.vnet.ibm.com Signed-off-by: Joel Fernandes (Google) joel@joelfernandes.org --- include/linux/srcu.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 2ec618979b20..a1c4947be877 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp) */ #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
+/** + * srcu_dereference_notrace - no tracing and no lockdep calls from here + */ +#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1) + /** * srcu_read_lock - register a new reader for an SRCU-protected structure. * @sp: srcu_struct in which to register the new reader.