OpenCloudOS-Kernel/include/linux/local_lock_internal.h

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locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_LOCAL_LOCK_H
# error "Do not include directly, include linux/local_lock.h"
#endif
#include <linux/percpu-defs.h>
#include <linux/lockdep.h>
#ifndef CONFIG_PREEMPT_RT
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
typedef struct {
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
struct task_struct *owner;
#endif
} local_lock_t;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define LOCAL_LOCK_DEBUG_INIT(lockname) \
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
.dep_map = { \
.name = #lockname, \
.wait_type_inner = LD_WAIT_CONFIG, \
.lock_type = LD_LOCK_PERCPU, \
}, \
.owner = NULL,
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
static inline void local_lock_acquire(local_lock_t *l)
{
lock_map_acquire(&l->dep_map);
DEBUG_LOCKS_WARN_ON(l->owner);
l->owner = current;
}
static inline void local_lock_release(local_lock_t *l)
{
DEBUG_LOCKS_WARN_ON(l->owner != current);
l->owner = NULL;
lock_map_release(&l->dep_map);
}
static inline void local_lock_debug_init(local_lock_t *l)
{
l->owner = NULL;
}
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
#else /* CONFIG_DEBUG_LOCK_ALLOC */
# define LOCAL_LOCK_DEBUG_INIT(lockname)
static inline void local_lock_acquire(local_lock_t *l) { }
static inline void local_lock_release(local_lock_t *l) { }
static inline void local_lock_debug_init(local_lock_t *l) { }
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
#define INIT_LOCAL_LOCK(lockname) { LOCAL_LOCK_DEBUG_INIT(lockname) }
#define __local_lock_init(lock) \
do { \
static struct lock_class_key __key; \
\
debug_check_no_locks_freed((void *)lock, sizeof(*lock));\
lockdep_init_map_type(&(lock)->dep_map, #lock, &__key, \
0, LD_WAIT_CONFIG, LD_WAIT_INV, \
LD_LOCK_PERCPU); \
local_lock_debug_init(lock); \
} while (0)
locking: Introduce local_lock() preempt_disable() and local_irq_disable/save() are in principle per CPU big kernel locks. This has several downsides: - The protection scope is unknown - Violation of protection rules is hard to detect by instrumentation - For PREEMPT_RT such sections, unless in low level critical code, can violate the preemptability constraints. To address this PREEMPT_RT introduced the concept of local_locks which are strictly per CPU. The lock operations map to preempt_disable(), local_irq_disable/save() and the enabling counterparts on non RT enabled kernels. If lockdep is enabled local locks gain a lock map which tracks the usage context. This will catch cases where an area is protected by preempt_disable() but the access also happens from interrupt context. local locks have identified quite a few such issues over the years, the most recent example is: b7d5dc21072cd ("random: add a spinlock_t to struct batched_entropy") Aside of the lockdep coverage this also improves code readability as it precisely annotates the protection scope. PREEMPT_RT substitutes these local locks with 'sleeping' spinlocks to protect such sections while maintaining preemtability and CPU locality. local locks can replace: - preempt_enable()/disable() pairs - local_irq_disable/enable() pairs - local_irq_save/restore() pairs They are also used to replace code which implicitly disables preemption like: - get_cpu()/put_cpu() - get_cpu_var()/put_cpu_var() with PREEMPT_RT friendly constructs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-2-bigeasy@linutronix.de
2020-05-28 04:11:13 +08:00
#define __local_lock(lock) \
do { \
preempt_disable(); \
local_lock_acquire(this_cpu_ptr(lock)); \
} 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(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)); \
local_irq_enable(); \
} while (0)
#define __local_unlock_irqrestore(lock, flags) \
do { \
local_lock_release(this_cpu_ptr(lock)); \
local_irq_restore(flags); \
} while (0)
#else /* !CONFIG_PREEMPT_RT */
/*
* On PREEMPT_RT local_lock maps to a per CPU spinlock, which protects the
* critical section while staying preemptible.
*/
typedef spinlock_t local_lock_t;
#define INIT_LOCAL_LOCK(lockname) __LOCAL_SPIN_LOCK_UNLOCKED((lockname))
#define __local_lock_init(l) \
do { \
local_spin_lock_init((l)); \
} while (0)
#define __local_lock(__lock) \
do { \
migrate_disable(); \
spin_lock(this_cpu_ptr((__lock))); \
} while (0)
#define __local_lock_irq(lock) __local_lock(lock)
#define __local_lock_irqsave(lock, flags) \
do { \
typecheck(unsigned long, flags); \
flags = 0; \
__local_lock(lock); \
} while (0)
#define __local_unlock(__lock) \
do { \
spin_unlock(this_cpu_ptr((__lock))); \
migrate_enable(); \
} while (0)
#define __local_unlock_irq(lock) __local_unlock(lock)
#define __local_unlock_irqrestore(lock, flags) __local_unlock(lock)
#endif /* CONFIG_PREEMPT_RT */