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Subject[PATCH v2 06/16] rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions
Date
Introduce helpers to lock and unlock per-cpu "kfree_rcu_cpu"
structures. That will make kfree_call_rcu() more readable
and prevent programming errors.

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
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 6501fbcae3c7..c1f4b740cf14 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2901,6 +2901,27 @@ 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.
@@ -3126,11 +3147,7 @@ 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.
@@ -3161,9 +3178,7 @@ 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
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