From: Peter Zijlstra <peterz@infradead.org>
To: elena.reshetova@intel.com, gregkh@linuxfoundation.org,
keescook@chromium.org, arnd@arndb.de, tglx@linutronix.de,
mingo@kernel.org, h.peter.anvin@intel.com, will.deacon@arm.com,
dwindsor@gmail.com, dhowells@redhat.com, peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com
Subject: [PATCH 2/5] kref: Implement using refcount_t
Date: Fri, 03 Feb 2017 14:26:00 +0100 [thread overview]
Message-ID: <20170203132737.365388918@infradead.org> (raw)
In-Reply-To: 20170203132558.474916683@infradead.org
[-- Attachment #1: peterz-ref-5a.patch --]
[-- Type: text/plain, Size: 2539 bytes --]
Use the refcount_t 'atomic' type to implement kref, this makes kref
more robust by bringing saturation semantics.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/kref.h | 29 +++++++++++------------------
1 file changed, 11 insertions(+), 18 deletions(-)
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -15,17 +15,14 @@
#ifndef _KREF_H_
#define _KREF_H_
-#include <linux/bug.h>
-#include <linux/atomic.h>
-#include <linux/kernel.h>
-#include <linux/mutex.h>
#include <linux/spinlock.h>
+#include <linux/refcount.h>
struct kref {
- atomic_t refcount;
+ refcount_t refcount;
};
-#define KREF_INIT(n) { .refcount = ATOMIC_INIT(n), }
+#define KREF_INIT(n) { .refcount = REFCOUNT_INIT(n), }
/**
* kref_init - initialize object.
@@ -33,12 +30,12 @@ struct kref {
*/
static inline void kref_init(struct kref *kref)
{
- atomic_set(&kref->refcount, 1);
+ refcount_set(&kref->refcount, 1);
}
-static inline int kref_read(const struct kref *kref)
+static inline unsigned int kref_read(const struct kref *kref)
{
- return atomic_read(&kref->refcount);
+ return refcount_read(&kref->refcount);
}
/**
@@ -47,11 +44,7 @@ static inline int kref_read(const struct
*/
static inline void kref_get(struct kref *kref)
{
- /* If refcount was 0 before incrementing then we have a race
- * condition when this kref is freeing by some other thread right now.
- * In this case one should use kref_get_unless_zero()
- */
- WARN_ON_ONCE(atomic_inc_return(&kref->refcount) < 2);
+ refcount_inc(&kref->refcount);
}
/**
@@ -75,7 +68,7 @@ static inline int kref_put(struct kref *
{
WARN_ON(release == NULL);
- if (atomic_dec_and_test(&kref->refcount)) {
+ if (refcount_dec_and_test(&kref->refcount)) {
release(kref);
return 1;
}
@@ -88,7 +81,7 @@ static inline int kref_put_mutex(struct
{
WARN_ON(release == NULL);
- if (atomic_dec_and_mutex_lock(&kref->refcount, lock)) {
+ if (refcount_dec_and_mutex_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
@@ -101,7 +94,7 @@ static inline int kref_put_lock(struct k
{
WARN_ON(release == NULL);
- if (atomic_dec_and_lock(&kref->refcount, lock)) {
+ if (refcount_dec_and_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
@@ -126,6 +119,6 @@ static inline int kref_put_lock(struct k
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
- return atomic_add_unless(&kref->refcount, 1, 0);
+ return refcount_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */
next prev parent reply other threads:[~2017-02-03 13:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-03 13:25 [PATCH 0/5] refcount_t and various related bits Peter Zijlstra
2017-02-03 13:25 ` [PATCH 1/5] refcount_t: A special purpose refcount type Peter Zijlstra
2017-02-03 18:09 ` Kees Cook
2017-02-03 23:37 ` Kees Cook
2017-02-03 13:26 ` Peter Zijlstra [this message]
2017-02-06 13:06 ` [PATCH 2/5] kref: Implement using refcount_t Greg KH
2017-02-03 13:26 ` [PATCH 3/5] x86: Implement __WARN using UD2 Peter Zijlstra
2017-02-03 13:26 ` [PATCH 4/5] atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra
2017-02-06 4:24 ` Boqun Feng
2017-02-06 6:32 ` Boqun Feng
2017-02-06 8:12 ` Peter Zijlstra
2017-02-03 13:26 ` [PATCH 5/5] refcount: Use atomic_try_cmpxchg() Peter Zijlstra
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