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From c13ea7a1c00bf021e2dd8fc58b9b6a00c554f22b Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 20 Jun 2011 09:03:47 +0200
Subject: [PATCH 194/323] rt: Add local irq locks
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.215-rt107.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 | 111 ++++++++++++++++++++++++++--
1 file changed, 103 insertions(+), 8 deletions(-)
diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 3f02b818625ef..1b8ae034946fa 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -7,13 +7,39 @@
#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
+#ifdef CONFIG_PREEMPT_RT
+
+#define INIT_LOCAL_LOCK(lockname) { \
+ __SPIN_LOCK_UNLOCKED((lockname).lock), \
+ .owner = NULL, \
+ .nestcnt = 0, \
+ }
+
+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)
+
+#elif defined(CONFIG_DEBUG_LOCK_ALLOC)
+
# define LOCAL_LOCK_DEBUG_INIT(lockname) \
.dep_map = { \
.name = #lockname, \
@@ -21,7 +47,33 @@ typedef struct {
.lock_type = LD_LOCK_PERCPU, \
}, \
.owner = NULL,
+#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);
+}
+
+#elif defined(CONFIG_DEBUG_LOCK_ALLOC)
static inline void local_lock_acquire(local_lock_t *l)
{
lock_map_acquire(&l->dep_map);
@@ -47,6 +99,47 @@ static inline void local_lock_release(local_lock_t *l) { }
static inline void local_lock_debug_init(local_lock_t *l) { }
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
+#ifdef CONFIG_PREEMPT_RT
+
+#define __local_lock(lock) \
+ do { \
+ 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 { \
+ migrate_disable(); \
+ local_lock_acquire(this_cpu_ptr(lock)); \
+ } while (0)
+
+#define __local_lock_irqsave(lock, flags) \
+ do { \
+ 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 INIT_LOCAL_LOCK(lockname) { LOCAL_LOCK_DEBUG_INIT(lockname) }
#define __local_lock_init(lock) \
@@ -66,6 +159,12 @@ do { \
local_lock_acquire(this_cpu_ptr(lock)); \
} while (0)
+#define __local_unlock(lock) \
+ do { \
+ local_lock_release(this_cpu_ptr(lock)); \
+ preempt_enable(); \
+ } while (0)
+
#define __local_lock_irq(lock) \
do { \
local_irq_disable(); \
@@ -78,12 +177,6 @@ do { \
local_lock_acquire(this_cpu_ptr(lock)); \
} while (0)
-#define __local_unlock(lock) \
- do { \
- local_lock_release(this_cpu_ptr(lock)); \
- preempt_enable(); \
- } while (0)
-
#define __local_unlock_irq(lock) \
do { \
local_lock_release(this_cpu_ptr(lock)); \
@@ -95,3 +188,5 @@ do { \
local_lock_release(this_cpu_ptr(lock)); \
local_irq_restore(flags); \
} while (0)
+
+#endif
--
2.44.0
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