70 lines
2.6 KiB
Diff
70 lines
2.6 KiB
Diff
From: Anna-Maria Gleixner <anna-maria@linutronix.de>
|
|
Date: Mon, 7 May 2018 16:44:57 +0200
|
|
Subject: [PATCH] locking/refcount: implement
|
|
refcount_dec_and_lock_irqsave()
|
|
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.16/older/patches-4.16.8-rt3.tar.xz
|
|
|
|
There are in-tree users of refcount_dec_and_lock() which must acquire the
|
|
spin lock with interrupts disabled. To workaround the lack of an irqsave
|
|
variant of refcount_dec_and_lock() they use local_irq_save() at the call
|
|
site. This causes extra code and creates in some places unneeded long
|
|
interrupt disabled times. These places need also extra treatment for
|
|
PREEMPT_RT due to the disconnect of the irq disabling and the lock
|
|
function.
|
|
|
|
Implement the missing irqsave variant of the function.
|
|
|
|
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
|
|
[bigeasy: s@atomic_dec_and_lock@refcount_dec_and_lock@g]
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
include/linux/refcount.h | 4 +++-
|
|
lib/refcount.c | 28 ++++++++++++++++++++++++++++
|
|
2 files changed, 31 insertions(+), 1 deletion(-)
|
|
|
|
--- a/include/linux/refcount.h
|
|
+++ b/include/linux/refcount.h
|
|
@@ -98,5 +98,7 @@ extern __must_check bool refcount_dec_if
|
|
extern __must_check bool refcount_dec_not_one(refcount_t *r);
|
|
extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
|
|
extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
|
|
-
|
|
+extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,
|
|
+ spinlock_t *lock,
|
|
+ unsigned long *flags);
|
|
#endif /* _LINUX_REFCOUNT_H */
|
|
--- a/lib/refcount.c
|
|
+++ b/lib/refcount.c
|
|
@@ -350,3 +350,31 @@ bool refcount_dec_and_lock(refcount_t *r
|
|
}
|
|
EXPORT_SYMBOL(refcount_dec_and_lock);
|
|
|
|
+/**
|
|
+ * refcount_dec_and_lock_irqsave - return holding spinlock with disabled
|
|
+ * interrupts if able to decrement refcount to 0
|
|
+ * @r: the refcount
|
|
+ * @lock: the spinlock to be locked
|
|
+ * @flags: saved IRQ-flags if the is acquired
|
|
+ *
|
|
+ * Same as refcount_dec_and_lock() above except that the spinlock is acquired
|
|
+ * with disabled interupts.
|
|
+ *
|
|
+ * Return: true and hold spinlock if able to decrement refcount to 0, false
|
|
+ * otherwise
|
|
+ */
|
|
+bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock,
|
|
+ unsigned long *flags)
|
|
+{
|
|
+ if (refcount_dec_not_one(r))
|
|
+ return false;
|
|
+
|
|
+ spin_lock_irqsave(lock, *flags);
|
|
+ if (!refcount_dec_and_test(r)) {
|
|
+ spin_unlock_irqrestore(lock, *flags);
|
|
+ return false;
|
|
+ }
|
|
+
|
|
+ return true;
|
|
+}
|
|
+EXPORT_SYMBOL(refcount_dec_and_lock_irqsave);
|