cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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locking.rst (2565B)

      1=======
      2Locking
      3=======
      4
      5This file explains the locking and exclusion scheme used in the PCCARD
      6and PCMCIA subsystems.
      7
      8
      9A) Overview, Locking Hierarchy:
     10===============================
     11
     12pcmcia_socket_list_rwsem
     13	- protects only the list of sockets
     14
     15- skt_mutex
     16	- serializes card insert / ejection
     17
     18  - ops_mutex
     19	- serializes socket operation
     20
     21
     22B) Exclusion
     23============
     24
     25The following functions and callbacks to struct pcmcia_socket must
     26be called with "skt_mutex" held::
     27
     28	socket_detect_change()
     29	send_event()
     30	socket_reset()
     31	socket_shutdown()
     32	socket_setup()
     33	socket_remove()
     34	socket_insert()
     35	socket_early_resume()
     36	socket_late_resume()
     37	socket_resume()
     38	socket_suspend()
     39
     40	struct pcmcia_callback	*callback
     41
     42The following functions and callbacks to struct pcmcia_socket must
     43be called with "ops_mutex" held::
     44
     45	socket_reset()
     46	socket_setup()
     47
     48	struct pccard_operations	*ops
     49	struct pccard_resource_ops	*resource_ops;
     50
     51Note that send_event() and `struct pcmcia_callback *callback` must not be
     52called with "ops_mutex" held.
     53
     54
     55C) Protection
     56=============
     57
     581. Global Data:
     59---------------
     60struct list_head	pcmcia_socket_list;
     61
     62protected by pcmcia_socket_list_rwsem;
     63
     64
     652. Per-Socket Data:
     66-------------------
     67The resource_ops and their data are protected by ops_mutex.
     68
     69The "main" struct pcmcia_socket is protected as follows (read-only fields
     70or single-use fields not mentioned):
     71
     72- by pcmcia_socket_list_rwsem::
     73
     74	struct list_head	socket_list;
     75
     76- by thread_lock::
     77
     78	unsigned int		thread_events;
     79
     80- by skt_mutex::
     81
     82	u_int			suspended_state;
     83	void			(*tune_bridge);
     84	struct pcmcia_callback	*callback;
     85	int			resume_status;
     86
     87- by ops_mutex::
     88
     89	socket_state_t		socket;
     90	u_int			state;
     91	u_short			lock_count;
     92	pccard_mem_map		cis_mem;
     93	void __iomem 		*cis_virt;
     94	struct { }		irq;
     95	io_window_t		io[];
     96	pccard_mem_map		win[];
     97	struct list_head	cis_cache;
     98	size_t			fake_cis_len;
     99	u8			*fake_cis;
    100	u_int			irq_mask;
    101	void 			(*zoom_video);
    102	int 			(*power_hook);
    103	u8			resource...;
    104	struct list_head	devices_list;
    105	u8			device_count;
    106	struct 			pcmcia_state;
    107
    108
    1093. Per PCMCIA-device Data:
    110--------------------------
    111
    112The "main" struct pcmcia_device is protected as follows (read-only fields
    113or single-use fields not mentioned):
    114
    115
    116- by pcmcia_socket->ops_mutex::
    117
    118	struct list_head	socket_device_list;
    119	struct config_t		*function_config;
    120	u16			_irq:1;
    121	u16			_io:1;
    122	u16			_win:4;
    123	u16			_locked:1;
    124	u16			allow_func_id_match:1;
    125	u16			suspended:1;
    126	u16			_removed:1;
    127
    128- by the PCMCIA driver::
    129
    130	io_req_t		io;
    131	irq_req_t		irq;
    132	config_req_t		conf;
    133	window_handle_t		win;