[PATCH 07/24] rcu/tree: move locking/unlocking to separate functions

Uladzislau Rezki (Sony)
2020-04-28T20:59:47Z

Introduce two helpers to lock and unlock an access to the
per-cpu "kfree_rcu_cpu" structure. The reason is to make
kfree_call_rcu() function to be more readable.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
kernel/rcu/tree.c | 31 +++++++++++++++++++++++--------
1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index eebd7f627794..bc6c2bc8fa32 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2925,6 +2925,27 @@ debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
#endif
}

+static inline struct kfree_rcu_cpu *
+krc_this_cpu_lock(unsigned long *flags)
+{
+ struct kfree_rcu_cpu *krcp;
+
+ local_irq_save(*flags); // For safely calling this_cpu_ptr().
+ krcp = this_cpu_ptr(&krc);
+ if (likely(krcp->initialized))
+ raw_spin_lock(&krcp->lock);
+
+ return krcp;
+}
+
+static inline void
+krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)
+{
+ if (likely(krcp->initialized))
+ raw_spin_unlock(&krcp->lock);
+ local_irq_restore(flags);
+}
+
/*
* This function is invoked in workqueue context after a grace period.
* It frees all the objects queued on ->bhead_free or ->head_free.
@@ -3150,11 +3171,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
struct kfree_rcu_cpu *krcp;
void *ptr;

- local_irq_save(flags); /* For safely calling this_cpu_ptr(). */
- krcp = this_cpu_ptr(&krc);
- if (krcp->initialized)
- raw_spin_lock(&krcp->lock);
-
+ krcp = krc_this_cpu_lock(&flags);
ptr = (void *)head - (unsigned long)func;

/* Queue the object but don't yet schedule the batch. */
@@ -3185,9 +3202,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
}

unlock_return:
- if (krcp->initialized)
- raw_spin_unlock(&krcp->lock);
- local_irq_restore(flags);
+ krc_this_cpu_unlock(krcp, flags);
}
EXPORT_SYMBOL_GPL(kfree_call_rcu);

--
2.20.1