From: Frederic Weisbecker <frederic@xxxxxxxxxx>
Checking for races against concurrent (de-)offloading implies the
creation of !CONFIG_RCU_NOCB_CPU stubs to check if each relevant lock
is held. For now this only implies the nocb_lock but more are to be
expected.
Create instead a NOCB specific version of RCU_LOCKDEP_WARN() to avoid
the proliferation of stubs.
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>
---
include/linux/rcupdate.h | 7 +++++++
kernel/rcu/tree_nocb.h | 14 --------------
kernel/rcu/tree_plugin.h | 4 ++--
3 files changed, 9 insertions(+), 16 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 13f6f00aecf9..d48d3c237305 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -144,11 +144,18 @@ void rcu_init_nohz(void);
int rcu_nocb_cpu_offload(int cpu);
int rcu_nocb_cpu_deoffload(int cpu);
void rcu_nocb_flush_deferred_wakeup(void);
+
+#define RCU_NOCB_LOCKDEP_WARN(c, s) RCU_LOCKDEP_WARN(c, s)
+
#else /* #ifdef CONFIG_RCU_NOCB_CPU */
+
static inline void rcu_init_nohz(void) { }
static inline int rcu_nocb_cpu_offload(int cpu) { return -EINVAL; }
static inline int rcu_nocb_cpu_deoffload(int cpu) { return 0; }
static inline void rcu_nocb_flush_deferred_wakeup(void) { }
+
+#define RCU_NOCB_LOCKDEP_WARN(c, s)
+
#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
/*
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 3ce30841119a..f4112fc663a7 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -16,10 +16,6 @@
#ifdef CONFIG_RCU_NOCB_CPU
static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
-static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)
-{
- return lockdep_is_held(&rdp->nocb_lock);
-}
static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
{
@@ -1653,16 +1649,6 @@ static void show_rcu_nocb_state(struct rcu_data *rdp)
#else /* #ifdef CONFIG_RCU_NOCB_CPU */
-static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)
-{
- return 0;
-}
-
-static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
-{
- return false;
-}
-
/* No ->nocb_lock to acquire. */
static void rcu_nocb_lock(struct rcu_data *rdp)
{
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index c569da65b421..f752b2a1d887 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -24,10 +24,10 @@ static bool rcu_rdp_is_offloaded(struct rcu_data *rdp)
* timers have their own means of synchronization against the
* offloaded state updaters.
*/
- RCU_LOCKDEP_WARN(
+ RCU_NOCB_LOCKDEP_WARN(
!(lockdep_is_held(&rcu_state.barrier_mutex) ||
(IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_held()) ||
- rcu_lockdep_is_held_nocb(rdp) ||
+ lockdep_is_held(&rdp->nocb_lock) ||
(!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible()) &&
rdp == this_cpu_ptr(&rcu_data)) ||
rcu_current_is_nocb_kthread(rdp)),
--
2.40.1
