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Message-Id: <20250801001236.4091760-2-paulmck@kernel.org>
Date: Thu, 31 Jul 2025 17:12:32 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
kernel-team@...a.com,
rostedt@...dmis.org,
"Paul E. McKenney" <paulmck@...nel.org>,
Joel Fernandes <joelagnelf@...dia.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
bpf@...r.kernel.org
Subject: [PATCH v5 2/6] 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: Paul E. McKenney <paulmck@...nel.org>
Reviewed-by: Joel Fernandes <joelagnelf@...dia.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: <bpf@...r.kernel.org>
---
include/linux/srcu.h | 25 +++++++++++++++++++++++++
include/linux/srcutree.h | 5 +++--
2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 478c73d067f7d..7a692bf8f99b9 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -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.
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 043b5a67ef71e..4d2fee4d38289 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -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))
--
2.40.1
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