Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / Documentation / pcmcia / locking.txt

diff --git a/kernel/Documentation/pcmcia/locking.txt b/kernel/Documentation/pcmcia/locking.txt
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+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
+       struct pccard_resource_ops      *resource_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 and their data are protected by ops_mutex.
+
+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;
+
+
+3. Per PCMCIA-device Data:
+--------------------------
+
+The "main" struct pcmcia_devie is protected as follows (read-only fields
+or single-use fields not mentioned):
+
+
+- by pcmcia_socket->ops_mutex:
+       struct list_head        socket_device_list;
+       struct config_t         *function_config;
+       u16                     _irq:1;
+       u16                     _io:1;
+       u16                     _win:4;
+       u16                     _locked:1;
+       u16                     allow_func_id_match:1;
+       u16                     suspended:1;
+       u16                     _removed:1;
+
+- by the PCMCIA driver:
+       io_req_t                io;
+       irq_req_t               irq;
+       config_req_t            conf;
+       window_handle_t         win;