Mailing List Archive

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Make it global so that it can be used in the future inlined rcu_read_unlock().

Make it exported so that the inlined rcu_read_unlock() can be used in modules.

Make it taking a void-argument so that the caller can reduce instructions
obtaining the "current" task value and it can be used in THUNK later.

Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
include/linux/rcupdate.h | 2 ++
kernel/rcu/tree_plugin.h | 7 ++++---
2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 210f65baf47c..cc77d76a870b 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -68,6 +68,8 @@ static inline bool same_state_synchronize_rcu(unsigned long oldstate1, unsigned

#ifdef CONFIG_PREEMPT_RCU

+void rcu_read_unlock_special(void);
+
void __rcu_read_lock(void);
void __rcu_read_unlock(void);

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 3dbd5609185e..880b3fef1158 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -104,7 +104,6 @@ static void __init rcu_bootup_announce_oddness(void)

static void rcu_report_exp_rnp(struct rcu_node *rnp, bool wake);
static bool sync_rcu_exp_done(struct rcu_node *rnp);
-static void rcu_read_unlock_special(struct task_struct *t);

#define set_rcu_preempt_special(reason) do { \
WRITE_ONCE(current->rcu_read_unlock_special.b.reason, true); \
@@ -427,7 +426,7 @@ void __rcu_read_unlock(void)
if (rcu_preempt_read_exit() == 0) {
barrier(); // critical-section exit before .s check.
if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s)))
- rcu_read_unlock_special(t);
+ rcu_read_unlock_special();
}
if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
int rrln = rcu_preempt_depth();
@@ -627,8 +626,9 @@ static void rcu_preempt_deferred_qs_handler(struct irq_work *iwp)
* notify RCU core processing or task having blocked during the RCU
* read-side critical section.
*/
-static void rcu_read_unlock_special(struct task_struct *t)
+void rcu_read_unlock_special(void)
{
+ struct task_struct *t = current;
unsigned long flags;
bool irqs_were_disabled;
bool preempt_bh_were_disabled =
@@ -684,6 +684,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
}
rcu_preempt_deferred_qs_irqrestore(t, flags);
}
+EXPORT_SYMBOL_GPL(rcu_read_unlock_special);

/*
* Check that the list of blocked tasks for the newly completed grace
--
2.19.1.6.gb485710b