=======
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Locking
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=======
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This file explains the locking and exclusion scheme used in the PCCARD
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and PCMCIA subsystems.
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A) Overview, Locking Hierarchy:
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===============================
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pcmcia_socket_list_rwsem
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- protects only the list of sockets
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- skt_mutex
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- serializes card insert / ejection
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- ops_mutex
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- serializes socket operation
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B) Exclusion
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============
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The following functions and callbacks to struct pcmcia_socket must
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be called with "skt_mutex" held::
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socket_detect_change()
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send_event()
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socket_reset()
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socket_shutdown()
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socket_setup()
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socket_remove()
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socket_insert()
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socket_early_resume()
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socket_late_resume()
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socket_resume()
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socket_suspend()
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struct pcmcia_callback *callback
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The following functions and callbacks to struct pcmcia_socket must
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be called with "ops_mutex" held::
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socket_reset()
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socket_setup()
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struct pccard_operations *ops
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struct pccard_resource_ops *resource_ops;
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Note that send_event() and `struct pcmcia_callback *callback` must not be
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called with "ops_mutex" held.
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C) Protection
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=============
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1. Global Data:
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---------------
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struct list_head pcmcia_socket_list;
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protected by pcmcia_socket_list_rwsem;
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2. Per-Socket Data:
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-------------------
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The resource_ops and their data are protected by ops_mutex.
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The "main" struct pcmcia_socket is protected as follows (read-only fields
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or single-use fields not mentioned):
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- by pcmcia_socket_list_rwsem::
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struct list_head socket_list;
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- by thread_lock::
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unsigned int thread_events;
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- by skt_mutex::
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u_int suspended_state;
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void (*tune_bridge);
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struct pcmcia_callback *callback;
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int resume_status;
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- by ops_mutex::
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socket_state_t socket;
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u_int state;
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u_short lock_count;
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pccard_mem_map cis_mem;
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void __iomem *cis_virt;
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struct { } irq;
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io_window_t io[];
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pccard_mem_map win[];
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struct list_head cis_cache;
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size_t fake_cis_len;
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u8 *fake_cis;
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u_int irq_mask;
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void (*zoom_video);
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int (*power_hook);
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u8 resource...;
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struct list_head devices_list;
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u8 device_count;
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struct pcmcia_state;
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3. Per PCMCIA-device Data:
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--------------------------
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The "main" struct pcmcia_device is protected as follows (read-only fields
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or single-use fields not mentioned):
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- by pcmcia_socket->ops_mutex::
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struct list_head socket_device_list;
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struct config_t *function_config;
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u16 _irq:1;
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u16 _io:1;
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u16 _win:4;
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u16 _locked:1;
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u16 allow_func_id_match:1;
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u16 suspended:1;
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u16 _removed:1;
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- by the PCMCIA driver::
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io_req_t io;
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irq_req_t irq;
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config_req_t conf;
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window_handle_t win;
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