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Subject: rt: Add local irq locks
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 20 Jun 2011 09:03:47 +0200
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.21-rt34.tar.xz
Introduce locallock. For !RT this maps to preempt_disable()/
local_irq_disable() so there is not much that changes. For RT this will
map to a spinlock. This makes preemption possible and locked "ressource"
gets the lockdep anotation it wouldn't have otherwise. The locks are
recursive for owner == current. Also, all locks user migrate_disable()
which ensures that the task is not migrated to another CPU while the lock
is held and the owner is preempted.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/local_lock_internal.h | 126 ++++++++++++++++++++++++++++++++----
1 file changed, 113 insertions(+), 13 deletions(-)
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -7,33 +7,90 @@
#include <linux/lockdep.h>
typedef struct {
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#ifdef CONFIG_PREEMPT_RT
+ spinlock_t lock;
+ struct task_struct *owner;
+ int nestcnt;
+
+#elif defined(CONFIG_DEBUG_LOCK_ALLOC)
struct lockdep_map dep_map;
struct task_struct *owner;
#endif
} local_lock_t;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define LL_DEP_MAP_INIT(lockname) \
+#ifdef CONFIG_PREEMPT_RT
+
+#define INIT_LOCAL_LOCK(lockname) { \
+ __SPIN_LOCK_UNLOCKED((lockname).lock), \
+ .owner = NULL, \
+ .nestcnt = 0, \
+ }
+#else
+
+# ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define LL_DEP_MAP_INIT(lockname) \
.dep_map = { \
.name = #lockname, \
.wait_type_inner = LD_WAIT_CONFIG, \
}
-#else
-# define LL_DEP_MAP_INIT(lockname)
-#endif
+# else
+# define LL_DEP_MAP_INIT(lockname)
+# endif
#define INIT_LOCAL_LOCK(lockname) { LL_DEP_MAP_INIT(lockname) }
-#define __local_lock_init(lock) \
+#endif
+
+#ifdef CONFIG_PREEMPT_RT
+
+static inline void ___local_lock_init(local_lock_t *l)
+{
+ l->owner = NULL;
+ l->nestcnt = 0;
+}
+
+#define __local_lock_init(l) \
+do { \
+ spin_lock_init(&(l)->lock); \
+ ___local_lock_init(l); \
+} while (0)
+
+#else
+
+#define __local_lock_init(l) \
do { \
static struct lock_class_key __key; \
\
- debug_check_no_locks_freed((void *)lock, sizeof(*lock));\
- lockdep_init_map_wait(&(lock)->dep_map, #lock, &__key, 0, LD_WAIT_CONFIG);\
+ debug_check_no_locks_freed((void *)l, sizeof(*l)); \
+ lockdep_init_map_wait(&(l)->dep_map, #l, &__key, 0, LD_WAIT_CONFIG);\
} while (0)
+#endif
+
+#ifdef CONFIG_PREEMPT_RT
+
+static inline void local_lock_acquire(local_lock_t *l)
+{
+ if (l->owner != current) {
+ spin_lock(&l->lock);
+ DEBUG_LOCKS_WARN_ON(l->owner);
+ DEBUG_LOCKS_WARN_ON(l->nestcnt);
+ l->owner = current;
+ }
+ l->nestcnt++;
+}
+
+static inline void local_lock_release(local_lock_t *l)
+{
+ DEBUG_LOCKS_WARN_ON(l->nestcnt == 0);
+ DEBUG_LOCKS_WARN_ON(l->owner != current);
+ if (--l->nestcnt)
+ return;
+
+ l->owner = NULL;
+ spin_unlock(&l->lock);
+}
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#elif defined(CONFIG_DEBUG_LOCK_ALLOC)
static inline void local_lock_acquire(local_lock_t *l)
{
lock_map_acquire(&l->dep_map);
@@ -53,21 +110,50 @@ static inline void local_lock_acquire(lo
static inline void local_lock_release(local_lock_t *l) { }
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
+#ifdef CONFIG_PREEMPT_RT
+
#define __local_lock(lock) \
do { \
- preempt_disable(); \
+ migrate_disable(); \
local_lock_acquire(this_cpu_ptr(lock)); \
} while (0)
+#define __local_unlock(lock) \
+ do { \
+ local_lock_release(this_cpu_ptr(lock)); \
+ migrate_enable(); \
+ } while (0)
+
#define __local_lock_irq(lock) \
do { \
- local_irq_disable(); \
+ migrate_disable(); \
local_lock_acquire(this_cpu_ptr(lock)); \
} while (0)
#define __local_lock_irqsave(lock, flags) \
do { \
- local_irq_save(flags); \
+ migrate_disable(); \
+ flags = 0; \
+ local_lock_acquire(this_cpu_ptr(lock)); \
+ } while (0)
+
+#define __local_unlock_irq(lock) \
+ do { \
+ local_lock_release(this_cpu_ptr(lock)); \
+ migrate_enable(); \
+ } while (0)
+
+#define __local_unlock_irqrestore(lock, flags) \
+ do { \
+ local_lock_release(this_cpu_ptr(lock)); \
+ migrate_enable(); \
+ } while (0)
+
+#else
+
+#define __local_lock(lock) \
+ do { \
+ preempt_disable(); \
local_lock_acquire(this_cpu_ptr(lock)); \
} while (0)
@@ -77,6 +163,18 @@ static inline void local_lock_release(lo
preempt_enable(); \
} while (0)
+#define __local_lock_irq(lock) \
+ do { \
+ local_irq_disable(); \
+ local_lock_acquire(this_cpu_ptr(lock)); \
+ } while (0)
+
+#define __local_lock_irqsave(lock, flags) \
+ do { \
+ local_irq_save(flags); \
+ local_lock_acquire(this_cpu_ptr(lock)); \
+ } while (0)
+
#define __local_unlock_irq(lock) \
do { \
local_lock_release(this_cpu_ptr(lock)); \
@@ -88,3 +186,5 @@ static inline void local_lock_release(lo
local_lock_release(this_cpu_ptr(lock)); \
local_irq_restore(flags); \
} while (0)
+
+#endif
|
