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2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f 
 kernel/include/linux/rwsem.h
....@@ -19,55 +19,55 @@
1919 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
2020 #include <linux/osq_lock.h>
2121 #endif
22
+#include <linux/android_vendor.h>
2223 
23
-#ifdef CONFIG_PREEMPT_RT_FULL
24
-#include <linux/rwsem_rt.h>
25
-#else /* PREEMPT_RT_FULL */
26
-
27
-struct rw_semaphore;
28
-
29
-#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
30
-#include <linux/rwsem-spinlock.h> /* use a generic implementation */
31
-#define __RWSEM_INIT_COUNT(name)	.count = RWSEM_UNLOCKED_VALUE
32
-#else
33
-/* All arch specific implementations share the same struct */
24
+/*
25
+ * For an uncontended rwsem, count and owner are the only fields a task
26
+ * needs to touch when acquiring the rwsem. So they are put next to each
27
+ * other to increase the chance that they will share the same cacheline.
28
+ *
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+ * In a contended rwsem, the owner is likely the most frequently accessed
30
+ * field in the structure as the optimistic waiter that holds the osq lock
31
+ * will spin on owner. For an embedded rwsem, other hot fields in the
32
+ * containing structure should be moved further away from the rwsem to
33
+ * reduce the chance that they will share the same cacheline causing
34
+ * cacheline bouncing problem.
35
+ */
3436 struct rw_semaphore {
3537 	atomic_long_t count;
36
-	struct list_head wait_list;
37
-	raw_spinlock_t wait_lock;
38
+	/*
39
+	 * Write owner or one of the read owners as well flags regarding
40
+	 * the current state of the rwsem. Can be used as a speculative
41
+	 * check to see if the write owner is running on the cpu.
42
+	 */
43
+	atomic_long_t owner;
3844 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
3945 	struct optimistic_spin_queue osq; /* spinner MCS lock */
40
-	/*
41
-	 * Write owner. Used as a speculative check to see
42
-	 * if the owner is running on the cpu.
43
-	 */
44
-	struct task_struct *owner;
46
+#endif
47
+	raw_spinlock_t wait_lock;
48
+	struct list_head wait_list;
49
+#ifdef CONFIG_DEBUG_RWSEMS
50
+	void *magic;
4551 #endif
4652 #ifdef CONFIG_DEBUG_LOCK_ALLOC
4753 	struct lockdep_map	dep_map;
4854 #endif
49
-        /* NOTICE: m_count is a vendor variable used for the config
50
-         * CONFIG_RWSEM_PRIO_AWARE. This is included here to maintain ABI
51
-         * compatibility with our vendors */
52
-        /* count for waiters preempt to queue in wait list */
53
-	long m_count;
55
+	ANDROID_VENDOR_DATA(1);
56
+	ANDROID_OEM_DATA_ARRAY(1, 2);
5457 };
5558 
56
-/*
57
- * Setting bit 0 of the owner field with other non-zero bits will indicate
58
- * that the rwsem is writer-owned with an unknown owner.
59
- */
60
-#define RWSEM_OWNER_UNKNOWN	((struct task_struct *)-1L)
59
+enum rwsem_waiter_type {
60
+	RWSEM_WAITING_FOR_WRITE,
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+	RWSEM_WAITING_FOR_READ
62
+};
6163 
62
-extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
63
-extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem);
64
-extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
65
-extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem);
66
-extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
67
-extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
68
-
69
-/* Include the arch specific part */
70
-#include <asm/rwsem.h>
64
+struct rwsem_waiter {
65
+	struct list_head list;
66
+	struct task_struct *task;
67
+	enum rwsem_waiter_type type;
68
+	unsigned long timeout;
69
+	unsigned long last_rowner;
70
+};
7171 
7272 /* In all implementations count != 0 means locked */
7373 static inline int rwsem_is_locked(struct rw_semaphore *sem)
....@@ -75,28 +75,40 @@
7575 	return atomic_long_read(&sem->count) != 0;
7676 }
7777 
78
-#define __RWSEM_INIT_COUNT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
79
-#endif
78
+#define RWSEM_UNLOCKED_VALUE		0L
79
+#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
8080 
8181 /* Common initializer macros and functions */
8282 
8383 #ifdef CONFIG_DEBUG_LOCK_ALLOC
84
-# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
84
+# define __RWSEM_DEP_MAP_INIT(lockname)			\
85
+	.dep_map = {					\
86
+		.name = #lockname,			\
87
+		.wait_type_inner = LD_WAIT_SLEEP,	\
88
+	},
8589 #else
8690 # define __RWSEM_DEP_MAP_INIT(lockname)
8791 #endif
8892 
93
+#ifdef CONFIG_DEBUG_RWSEMS
94
+# define __RWSEM_DEBUG_INIT(lockname) .magic = &lockname,
95
+#else
96
+# define __RWSEM_DEBUG_INIT(lockname)
97
+#endif
98
+
8999 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
90
-#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED, .owner = NULL
100
+#define __RWSEM_OPT_INIT(lockname) .osq = OSQ_LOCK_UNLOCKED,
91101 #else
92102 #define __RWSEM_OPT_INIT(lockname)
93103 #endif
94104 
95105 #define __RWSEM_INITIALIZER(name)				\
96
-	{ __RWSEM_INIT_COUNT(name),				\
97
-	  .wait_list = LIST_HEAD_INIT((name).wait_list),	\
98
-	  .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock)	\
106
+	{ __RWSEM_COUNT_INIT(name),				\
107
+	  .owner = ATOMIC_LONG_INIT(0),				\
99108 	  __RWSEM_OPT_INIT(name)				\
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+	  .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock),\
110
+	  .wait_list = LIST_HEAD_INIT((name).wait_list),	\
111
+	  __RWSEM_DEBUG_INIT(name)				\
100112 	  __RWSEM_DEP_MAP_INIT(name) }
101113 
102114 #define DECLARE_RWSEM(name) \
....@@ -123,17 +135,11 @@
123135 	return !list_empty(&sem->wait_list);
124136 }
125137 
126
-#endif /* !PREEMPT_RT_FULL */
127
-
128
-/*
129
- * The functions below are the same for all rwsem implementations including
130
- * the RT specific variant.
131
- */
132
-
133138 /*
134139  * lock for reading
135140  */
136141 extern void down_read(struct rw_semaphore *sem);
142
+extern int __must_check down_read_interruptible(struct rw_semaphore *sem);
137143 extern int __must_check down_read_killable(struct rw_semaphore *sem);
138144 
139145 /*
....@@ -179,9 +185,10 @@
179185  * static then another method for expressing nested locking is
180186  * the explicit definition of lock class keys and the use of
181187  * lockdep_set_class() at lock initialization time.
182
- * See Documentation/locking/lockdep-design.txt for more details.)
188
+ * See Documentation/locking/lockdep-design.rst for more details.)
183189  */
184190 extern void down_read_nested(struct rw_semaphore *sem, int subclass);
191
+extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass);
185192 extern void down_write_nested(struct rw_semaphore *sem, int subclass);
186193 extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass);
187194 extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);
....@@ -202,6 +209,7 @@
202209 extern void up_read_non_owner(struct rw_semaphore *sem);
203210 #else
204211 # define down_read_nested(sem, subclass)		down_read(sem)
212
+# define down_read_killable_nested(sem, subclass)	down_read_killable(sem)
205213 # define down_write_nest_lock(sem, nest_lock)	down_write(sem)
206214 # define down_write_nested(sem, subclass)	down_write(sem)
207215 # define down_write_killable_nested(sem, subclass)	down_write_killable(sem)