Commit 7e2a2d06 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

srcu: Add srcu_read_lock_fast_notrace() and srcu_read_unlock_fast_notrace() 

This commit adds no-trace variants of the srcu_read_lock_fast() and
srcu_read_unlock_fast() functions for tracing use.

[ paulmck: Apply notrace feedback from Joel Fernandes, Steven Rostedt, and Mathieu Desnoyers. ]
[ paulmck: Apply excess-notrace feedback from Boqun Feng. ]

Link: https://lore.kernel.org/all/20250721162433.10454-1-paulmck@kernel.org


Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <bpf@vger.kernel.org>
parent f3949408

include/linux/srcu.h

+25 −0
Original line number Diff line number Diff line
@@ -282,6 +282,20 @@ static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct * 
	return retval;

}



/*

 * Used by tracing, cannot be traced and cannot call lockdep.

 * See srcu_read_lock_fast() for more information.

 */

static inline struct srcu_ctr __percpu *srcu_read_lock_fast_notrace(struct srcu_struct *ssp)

	__acquires(ssp)

{

	struct srcu_ctr __percpu *retval;



	srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_FAST);

	retval = __srcu_read_lock_fast(ssp);

	return retval;

}



/**

 * srcu_down_read_fast - register a new reader for an SRCU-protected structure.

 * @ssp: srcu_struct in which to register the new reader.
@@ -394,6 +408,17 @@ static inline void srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ct 
	RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_unlock_fast().");

}



/*

 * Used by tracing, cannot be traced and cannot call lockdep.

 * See srcu_read_unlock_fast() for more information.

 */

static inline void srcu_read_unlock_fast_notrace(struct srcu_struct *ssp,

						 struct srcu_ctr __percpu *scp) __releases(ssp)

{

	srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST);

	__srcu_read_unlock_fast(ssp, scp);

}



/**

 * srcu_up_read_fast - unregister a old reader from an SRCU-protected structure.

 * @ssp: srcu_struct in which to unregister the old reader.

include/linux/srcutree.h

+3 −2
Original line number Diff line number Diff line
@@ -240,7 +240,7 @@ static inline struct srcu_ctr __percpu *__srcu_ctr_to_ptr(struct srcu_struct *ss 
 * on architectures that support NMIs but do not supply NMI-safe

 * implementations of this_cpu_inc().

 */

static inline struct srcu_ctr __percpu *__srcu_read_lock_fast(struct srcu_struct *ssp)

static inline struct srcu_ctr __percpu notrace *__srcu_read_lock_fast(struct srcu_struct *ssp)

{

	struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp);
@@ -267,7 +267,8 @@ static inline struct srcu_ctr __percpu *__srcu_read_lock_fast(struct srcu_struct 
 * on architectures that support NMIs but do not supply NMI-safe

 * implementations of this_cpu_inc().

 */

static inline void __srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp)

static inline void notrace

__srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp)

{

	barrier();  /* Avoid leaking the critical section. */

	if (!IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE))