1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
4  * Module Name: utlock - Reader/Writer lock interfaces
6  * Copyright (C) 2000 - 2023, Intel Corp.
21  * PARAMETERS:  lock                - Pointer to a valid RW lock
23  * RETURN:      Status
25  * DESCRIPTION: Reader/writer lock creation and deletion interfaces.
28 acpi_status acpi_ut_create_rw_lock(struct acpi_rw_lock *lock)  in acpi_ut_create_rw_lock()  argument
30 	acpi_status status;  in acpi_ut_create_rw_lock()  local
32 	lock->num_readers = 0;  in acpi_ut_create_rw_lock()
33 	status = acpi_os_create_mutex(&lock->reader_mutex);  in acpi_ut_create_rw_lock()
34 	if (ACPI_FAILURE(status)) {  in acpi_ut_create_rw_lock()
35 		return (status);  in acpi_ut_create_rw_lock()
38 	status = acpi_os_create_mutex(&lock->writer_mutex);  in acpi_ut_create_rw_lock()
39 	return (status);  in acpi_ut_create_rw_lock()
42 void acpi_ut_delete_rw_lock(struct acpi_rw_lock *lock)  in acpi_ut_delete_rw_lock()  argument
45 	acpi_os_delete_mutex(lock->reader_mutex);  in acpi_ut_delete_rw_lock()
46 	acpi_os_delete_mutex(lock->writer_mutex);  in acpi_ut_delete_rw_lock()
48 	lock->num_readers = 0;  in acpi_ut_delete_rw_lock()
49 	lock->reader_mutex = NULL;  in acpi_ut_delete_rw_lock()
50 	lock->writer_mutex = NULL;  in acpi_ut_delete_rw_lock()
58  * PARAMETERS:  lock                - Pointer to a valid RW lock
60  * RETURN:      Status
71 acpi_status acpi_ut_acquire_read_lock(struct acpi_rw_lock *lock)  in acpi_ut_acquire_read_lock()  argument
73 	acpi_status status;  in acpi_ut_acquire_read_lock()  local
75 	status = acpi_os_acquire_mutex(lock->reader_mutex, ACPI_WAIT_FOREVER);  in acpi_ut_acquire_read_lock()
76 	if (ACPI_FAILURE(status)) {  in acpi_ut_acquire_read_lock()
77 		return (status);  in acpi_ut_acquire_read_lock()
80 	/* Acquire the write lock only for the first reader */  in acpi_ut_acquire_read_lock()
82 	lock->num_readers++;  in acpi_ut_acquire_read_lock()
83 	if (lock->num_readers == 1) {  in acpi_ut_acquire_read_lock()
84 		status =  in acpi_ut_acquire_read_lock()
85 		    acpi_os_acquire_mutex(lock->writer_mutex,  in acpi_ut_acquire_read_lock()
89 	acpi_os_release_mutex(lock->reader_mutex);  in acpi_ut_acquire_read_lock()
90 	return (status);  in acpi_ut_acquire_read_lock()
93 acpi_status acpi_ut_release_read_lock(struct acpi_rw_lock *lock)  in acpi_ut_release_read_lock()  argument
95 	acpi_status status;  in acpi_ut_release_read_lock()  local
97 	status = acpi_os_acquire_mutex(lock->reader_mutex, ACPI_WAIT_FOREVER);  in acpi_ut_release_read_lock()
98 	if (ACPI_FAILURE(status)) {  in acpi_ut_release_read_lock()
99 		return (status);  in acpi_ut_release_read_lock()
102 	/* Release the write lock only for the very last reader */  in acpi_ut_release_read_lock()
104 	lock->num_readers--;  in acpi_ut_release_read_lock()
105 	if (lock->num_readers == 0) {  in acpi_ut_release_read_lock()
106 		acpi_os_release_mutex(lock->writer_mutex);  in acpi_ut_release_read_lock()
109 	acpi_os_release_mutex(lock->reader_mutex);  in acpi_ut_release_read_lock()
110 	return (status);  in acpi_ut_release_read_lock()
118  * PARAMETERS:  lock                - Pointer to a valid RW lock
120  * RETURN:      Status
123  *              release the writer mutex associated with the lock. Acquisition
124  *              of the lock is fully exclusive and will block all readers and
129 acpi_status acpi_ut_acquire_write_lock(struct acpi_rw_lock *lock)  in acpi_ut_acquire_write_lock()  argument
131 	acpi_status status;  in acpi_ut_acquire_write_lock()  local
133 	status = acpi_os_acquire_mutex(lock->writer_mutex, ACPI_WAIT_FOREVER);  in acpi_ut_acquire_write_lock()
134 	return (status);  in acpi_ut_acquire_write_lock()
137 void acpi_ut_release_write_lock(struct acpi_rw_lock *lock)  in acpi_ut_release_write_lock()  argument
140 	acpi_os_release_mutex(lock->writer_mutex);  in acpi_ut_release_write_lock()