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rcu/nocb: Introduce RCU_NOCB_LOCKDEP_WARN()

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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@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
This commit is contained in:
Frederic Weisbecker 2024-05-30 15:45:42 +02:00 committed by Neeraj Upadhyay
parent 8400291e28
commit 7aeba709a0
3 changed files with 9 additions and 16 deletions
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7
include/linux/rcupdate.h
View File

@ -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 */
/*

14
kernel/rcu/tree_nocb.h
View File

@ -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)
{

4
kernel/rcu/tree_plugin.h
View File

@ -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)),