| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | This file explains the locking and exclusion scheme used in the PCCARD |
| 2 | and PCMCIA subsystems. |
| 3 | |
| 4 | |
| 5 | A) Overview, Locking Hierarchy: |
| 6 | =============================== |
| 7 | |
| 8 | pcmcia_socket_list_rwsem - protects only the list of sockets |
| 9 | - skt_mutex - serializes card insert / ejection |
| 10 | - ops_mutex - serializes socket operation |
| 11 | |
| 12 | |
| 13 | B) Exclusion |
| 14 | ============ |
| 15 | |
| 16 | The following functions and callbacks to struct pcmcia_socket must |
| 17 | be called with "skt_mutex" held: |
| 18 | |
| 19 | socket_detect_change() |
| 20 | send_event() |
| 21 | socket_reset() |
| 22 | socket_shutdown() |
| 23 | socket_setup() |
| 24 | socket_remove() |
| 25 | socket_insert() |
| 26 | socket_early_resume() |
| 27 | socket_late_resume() |
| 28 | socket_resume() |
| 29 | socket_suspend() |
| 30 | |
| 31 | struct pcmcia_callback *callback |
| 32 | |
| 33 | The following functions and callbacks to struct pcmcia_socket must |
| 34 | be called with "ops_mutex" held: |
| 35 | |
| 36 | socket_reset() |
| 37 | socket_setup() |
| 38 | |
| 39 | struct pccard_operations *ops |
| 40 | struct pccard_resource_ops *resource_ops; |
| 41 | |
| 42 | Note that send_event() and struct pcmcia_callback *callback must not be |
| 43 | called with "ops_mutex" held. |
| 44 | |
| 45 | |
| 46 | C) Protection |
| 47 | ============= |
| 48 | |
| 49 | 1. Global Data: |
| 50 | --------------- |
| 51 | struct list_head pcmcia_socket_list; |
| 52 | |
| 53 | protected by pcmcia_socket_list_rwsem; |
| 54 | |
| 55 | |
| 56 | 2. Per-Socket Data: |
| 57 | ------------------- |
| 58 | The resource_ops and their data are protected by ops_mutex. |
| 59 | |
| 60 | The "main" struct pcmcia_socket is protected as follows (read-only fields |
| 61 | or single-use fields not mentioned): |
| 62 | |
| 63 | - by pcmcia_socket_list_rwsem: |
| 64 | struct list_head socket_list; |
| 65 | |
| 66 | - by thread_lock: |
| 67 | unsigned int thread_events; |
| 68 | |
| 69 | - by skt_mutex: |
| 70 | u_int suspended_state; |
| 71 | void (*tune_bridge); |
| 72 | struct pcmcia_callback *callback; |
| 73 | int resume_status; |
| 74 | |
| 75 | - by ops_mutex: |
| 76 | socket_state_t socket; |
| 77 | u_int state; |
| 78 | u_short lock_count; |
| 79 | pccard_mem_map cis_mem; |
| 80 | void __iomem *cis_virt; |
| 81 | struct { } irq; |
| 82 | io_window_t io[]; |
| 83 | pccard_mem_map win[]; |
| 84 | struct list_head cis_cache; |
| 85 | size_t fake_cis_len; |
| 86 | u8 *fake_cis; |
| 87 | u_int irq_mask; |
| 88 | void (*zoom_video); |
| 89 | int (*power_hook); |
| 90 | u8 resource...; |
| 91 | struct list_head devices_list; |
| 92 | u8 device_count; |
| 93 | struct pcmcia_state; |
| 94 | |
| 95 | |
| 96 | 3. Per PCMCIA-device Data: |
| 97 | -------------------------- |
| 98 | |
| 99 | The "main" struct pcmcia_device is protected as follows (read-only fields |
| 100 | or single-use fields not mentioned): |
| 101 | |
| 102 | |
| 103 | - by pcmcia_socket->ops_mutex: |
| 104 | struct list_head socket_device_list; |
| 105 | struct config_t *function_config; |
| 106 | u16 _irq:1; |
| 107 | u16 _io:1; |
| 108 | u16 _win:4; |
| 109 | u16 _locked:1; |
| 110 | u16 allow_func_id_match:1; |
| 111 | u16 suspended:1; |
| 112 | u16 _removed:1; |
| 113 | |
| 114 | - by the PCMCIA driver: |
| 115 | io_req_t io; |
| 116 | irq_req_t irq; |
| 117 | config_req_t conf; |
| 118 | window_handle_t win; |