aboutsummaryrefslogtreecommitdiff
path: root/Documentation/pcmcia/locking.txt
blob: 5f25de4cdb4206a10741d8ad2a011817aab0f109 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
This file explains the locking and exclusion scheme used in the PCCARD
and PCMCIA subsystems.


A) Overview, Locking Hierarchy:
===============================

pcmcia_socket_list_rwsem	- protects only the list of sockets
- skt_mutex			- serializes card insert / ejection
  - ops_mutex			- serializes socket operation


B) Exclusion
============

The following functions and callbacks to struct pcmcia_socket must
be called with "skt_mutex" held:

	socket_detect_change()
	send_event()
	socket_reset()
	socket_shutdown()
	socket_setup()
	socket_remove()
	socket_insert()
	socket_early_resume()
	socket_late_resume()
	socket_resume()
	socket_suspend()

	struct pcmcia_callback	*callback

The following functions and callbacks to struct pcmcia_socket must
be called with "ops_mutex" held:

	socket_reset()
	socket_setup()

	struct pccard_operations *ops

Note that send_event() and struct pcmcia_callback *callback must not be
called with "ops_mutex" held.


C) Protection
=============

1. Global Data:
---------------
struct list_head	pcmcia_socket_list;

protected by pcmcia_socket_list_rwsem;


2. Per-Socket Data:
-------------------
The resource_ops are on their own to provide proper locking.

The "main" struct pcmcia_socket is protected as follows (read-only fields
or single-use fields not mentioned):

- by pcmcia_socket_list_rwsem:
	struct list_head	socket_list;

- by thread_lock:
	unsigned int		thread_events;

- by skt_mutex:
	u_int			suspended_state;
	void			(*tune_bridge);
	struct pcmcia_callback	*callback;
	int			resume_status;

- by ops_mutex:
	socket_state_t		socket;
	u_int			state;
	u_short			lock_count;
	pccard_mem_map		cis_mem;
	void __iomem 		*cis_virt;
	struct { }		irq;
	io_window_t		io[];
	pccard_mem_map		win[];
	struct list_head	cis_cache;
	size_t			fake_cis_len;
	u8			*fake_cis;
	u_int			irq_mask;
	void 			(*zoom_video);
	int 			(*power_hook);
	u8			resource...;
	struct list_head	devices_list;
	u8			device_count;
	struct 			pcmcia_state;