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Date: Thu, 29 Dec 2016 08:55:56 +0200
From: Elena Reshetova <elena.reshetova@...el.com>
To: kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
arnd@...db.de,
tglx@...utronix.de,
mingo@...hat.com,
h.peter.anvin@...el.com,
peterz@...radead.org,
will.deacon@....com,
dwindsor@...il.com,
gregkh@...uxfoundation.org,
ishkamiel@...il.com,
Elena Reshetova <elena.reshetova@...el.com>
Subject: [RFC PATCH 04/19] Because home-rolling your own is _awesome_, stop doing it. Provide kref_put_lock(), just like kref_put_mutex() but for a spinlock.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
include/linux/kref.h | 21 +++++++++++++++------
net/sunrpc/svcauth.c | 15 ++++++++++-----
2 files changed, 25 insertions(+), 11 deletions(-)
diff --git a/include/linux/kref.h b/include/linux/kref.h
index ad8050a..a5181bd 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -84,12 +84,21 @@ static inline int kref_put_mutex(struct kref *kref,
struct mutex *lock)
{
WARN_ON(release == NULL);
- if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
- mutex_lock(lock);
- if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
- mutex_unlock(lock);
- return 0;
- }
+
+ if (atomic_dec_and_mutex_lock(&kref->refcount, lock)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
+
+static inline int kref_put_lock(struct kref *kref,
+ void (*release)(struct kref *kref),
+ spinlock_t *lock)
+{
+ WARN_ON(release == NULL);
+
+ if (atomic_dec_and_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
diff --git a/net/sunrpc/svcauth.c b/net/sunrpc/svcauth.c
index e112da8..bb8db3c 100644
--- a/net/sunrpc/svcauth.c
+++ b/net/sunrpc/svcauth.c
@@ -126,13 +126,18 @@ EXPORT_SYMBOL_GPL(svc_auth_unregister);
static struct hlist_head auth_domain_table[DN_HASHMAX];
static DEFINE_SPINLOCK(auth_domain_lock);
+static void auth_domain_release(struct kref *kref)
+{
+ struct auth_domain *dom = container_of(kref, struct auth_domain, ref);
+
+ hlist_del(&dom->hash);
+ dom->flavour->domain_release(dom);
+ spin_unlock(&auth_domain_lock);
+}
+
void auth_domain_put(struct auth_domain *dom)
{
- if (atomic_dec_and_lock(&dom->ref.refcount, &auth_domain_lock)) {
- hlist_del(&dom->hash);
- dom->flavour->domain_release(dom);
- spin_unlock(&auth_domain_lock);
- }
+ kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock);
}
EXPORT_SYMBOL_GPL(auth_domain_put);
--
2.7.4
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