From 6778948f9de86c3cfaf36725a7c87dcff9ba247f Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Mon, 11 Dec 2023 08:20:59 +0000
Subject: [PATCH] kernel_5.10 no rt
---
kernel/include/linux/rwsem.h | 101 ++++++++++++++++++++++++++++++--------------------
1 files changed, 60 insertions(+), 41 deletions(-)
diff --git a/kernel/include/linux/rwsem.h b/kernel/include/linux/rwsem.h
index 93c2235..e851cd5 100644
--- a/kernel/include/linux/rwsem.h
+++ b/kernel/include/linux/rwsem.h
@@ -19,51 +19,55 @@
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
#include <linux/osq_lock.h>
#endif
+#include <linux/android_vendor.h>
-struct rw_semaphore;
-
-#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
-#include <linux/rwsem-spinlock.h> /* use a generic implementation */
-#define __RWSEM_INIT_COUNT(name) .count = RWSEM_UNLOCKED_VALUE
-#else
-/* All arch specific implementations share the same struct */
+/*
+ * For an uncontended rwsem, count and owner are the only fields a task
+ * needs to touch when acquiring the rwsem. So they are put next to each
+ * other to increase the chance that they will share the same cacheline.
+ *
+ * In a contended rwsem, the owner is likely the most frequently accessed
+ * field in the structure as the optimistic waiter that holds the osq lock
+ * will spin on owner. For an embedded rwsem, other hot fields in the
+ * containing structure should be moved further away from the rwsem to
+ * reduce the chance that they will share the same cacheline causing
+ * cacheline bouncing problem.
+ */
struct rw_semaphore {
atomic_long_t count;
- struct list_head wait_list;
- raw_spinlock_t wait_lock;
+ /*
+ * Write owner or one of the read owners as well flags regarding
+ * the current state of the rwsem. Can be used as a speculative
+ * check to see if the write owner is running on the cpu.
+ */
+ atomic_long_t owner;
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
struct optimistic_spin_queue osq; /* spinner MCS lock */
- /*
- * Write owner. Used as a speculative check to see
- * if the owner is running on the cpu.
- */
- struct task_struct *owner;
+#endif
+ raw_spinlock_t wait_lock;
+ struct list_head wait_list;
+#ifdef CONFIG_DEBUG_RWSEMS
+ void *magic;
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
- /* NOTICE: m_count is a vendor variable used for the config
- * CONFIG_RWSEM_PRIO_AWARE. This is included here to maintain ABI
- * compatibility with our vendors */
- /* count for waiters preempt to queue in wait list */
- long m_count;
+ ANDROID_VENDOR_DATA(1);
+ ANDROID_OEM_DATA_ARRAY(1, 2);
};
-/*
- * Setting bit 0 of the owner field with other non-zero bits will indicate
- * that the rwsem is writer-owned with an unknown owner.
- */
-#define RWSEM_OWNER_UNKNOWN ((struct task_struct *)-1L)
+enum rwsem_waiter_type {
+ RWSEM_WAITING_FOR_WRITE,
+ RWSEM_WAITING_FOR_READ
+};
-extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
-extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
-
-/* Include the arch specific part */
-#include <asm/rwsem.h>
+struct rwsem_waiter {
+ struct list_head list;
+ struct task_struct *task;
+ enum rwsem_waiter_type type;
+ unsigned long timeout;
+ unsigned long last_rowner;
+};
/* In all implementations count != 0 means locked */
static inline int rwsem_is_locked(struct rw_semaphore *sem)
@@ -71,28 +75,40 @@
return atomic_long_read(&sem->count) != 0;
}
-#define __RWSEM_INIT_COUNT(name) .count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
-#endif
+#define RWSEM_UNLOCKED_VALUE 0L
+#define __RWSEM_COUNT_INIT(name) .count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
/* Common initializer macros and functions */
#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
+# define __RWSEM_DEP_MAP_INIT(lockname) \
+ .dep_map = { \
+ .name = #lockname, \
+ .wait_type_inner = LD_WAIT_SLEEP, \
+ },
#else
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif
+#ifdef CONFIG_DEBUG_RWSEMS
+# define __RWSEM_DEBUG_INIT(lockname) .magic = &lockname,
+#else
+# define __RWSEM_DEBUG_INIT(lockname)
+#endif
+
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
-#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED, .owner = NULL
+#define __RWSEM_OPT_INIT(lockname) .osq = OSQ_LOCK_UNLOCKED,
#else
#define __RWSEM_OPT_INIT(lockname)
#endif
#define __RWSEM_INITIALIZER(name) \
- { __RWSEM_INIT_COUNT(name), \
- .wait_list = LIST_HEAD_INIT((name).wait_list), \
- .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock) \
+ { __RWSEM_COUNT_INIT(name), \
+ .owner = ATOMIC_LONG_INIT(0), \
__RWSEM_OPT_INIT(name) \
+ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock),\
+ .wait_list = LIST_HEAD_INIT((name).wait_list), \
+ __RWSEM_DEBUG_INIT(name) \
__RWSEM_DEP_MAP_INIT(name) }
#define DECLARE_RWSEM(name) \
@@ -123,6 +139,7 @@
* lock for reading
*/
extern void down_read(struct rw_semaphore *sem);
+extern int __must_check down_read_interruptible(struct rw_semaphore *sem);
extern int __must_check down_read_killable(struct rw_semaphore *sem);
/*
@@ -168,9 +185,10 @@
* static then another method for expressing nested locking is
* the explicit definition of lock class keys and the use of
* lockdep_set_class() at lock initialization time.
- * See Documentation/locking/lockdep-design.txt for more details.)
+ * See Documentation/locking/lockdep-design.rst for more details.)
*/
extern void down_read_nested(struct rw_semaphore *sem, int subclass);
+extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass);
extern void down_write_nested(struct rw_semaphore *sem, int subclass);
extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass);
extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);
@@ -191,6 +209,7 @@
extern void up_read_non_owner(struct rw_semaphore *sem);
#else
# define down_read_nested(sem, subclass) down_read(sem)
+# define down_read_killable_nested(sem, subclass) down_read_killable(sem)
# define down_write_nest_lock(sem, nest_lock) down_write(sem)
# define down_write_nested(sem, subclass) down_write(sem)
# define down_write_killable_nested(sem, subclass) down_write_killable(sem)
--
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