Input: implement proper locking in input core
Also add some kerneldoc documentation to input.h
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/input.h b/include/linux/input.h
index adfbe4f..d09e5e8 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -845,7 +845,7 @@
* defining effect parameters
*
* This structure is sent through ioctl from the application to the driver.
- * To create a new effect aplication should set its @id to -1; the kernel
+ * To create a new effect application should set its @id to -1; the kernel
* will return assigned @id which can later be used to update or delete
* this effect.
*
@@ -925,9 +925,82 @@
#define BIT(x) (1UL<<((x)%BITS_PER_LONG))
#define LONG(x) ((x)/BITS_PER_LONG)
+/**
+ * struct input_dev - represents an input device
+ * @name: name of the device
+ * @phys: physical path to the device in the system hierarchy
+ * @uniq: unique identification code for the device (if device has it)
+ * @id: id of the device (struct input_id)
+ * @evbit: bitmap of types of events supported by the device (EV_KEY,
+ * EV_REL, etc.)
+ * @keybit: bitmap of keys/buttons this device has
+ * @relbit: bitmap of relative axes for the device
+ * @absbit: bitmap of absolute axes for the device
+ * @mscbit: bitmap of miscellaneous events supported by the device
+ * @ledbit: bitmap of leds present on the device
+ * @sndbit: bitmap of sound effects supported by the device
+ * @ffbit: bitmap of force feedback effects supported by the device
+ * @swbit: bitmap of switches present on the device
+ * @keycodemax: size of keycode table
+ * @keycodesize: size of elements in keycode table
+ * @keycode: map of scancodes to keycodes for this device
+ * @setkeycode: optional method to alter current keymap, used to implement
+ * sparse keymaps. If not supplied default mechanism will be used
+ * @getkeycode: optional method to retrieve current keymap. If not supplied
+ * default mechanism will be used
+ * @ff: force feedback structure associated with the device if device
+ * supports force feedback effects
+ * @repeat_key: stores key code of the last key pressed; used to implement
+ * software autorepeat
+ * @timer: timer for software autorepeat
+ * @sync: set to 1 when there were no new events since last EV_SYNC
+ * @abs: current values for reports from absolute axes
+ * @rep: current values for autorepeat parameters (delay, rate)
+ * @key: reflects current state of device's keys/buttons
+ * @led: reflects current state of device's LEDs
+ * @snd: reflects current state of sound effects
+ * @sw: reflects current state of device's switches
+ * @absmax: maximum values for events coming from absolute axes
+ * @absmin: minimum values for events coming from absolute axes
+ * @absfuzz: describes noisiness for axes
+ * @absflat: size of the center flat position (used by joydev)
+ * @open: this method is called when the very first user calls
+ * input_open_device(). The driver must prepare the device
+ * to start generating events (start polling thread,
+ * request an IRQ, submit URB, etc.)
+ * @close: this method is called when the very last user calls
+ * input_close_device().
+ * @flush: purges the device. Most commonly used to get rid of force
+ * feedback effects loaded into the device when disconnecting
+ * from it
+ * @event: event handler for events sent _to_ the device, like EV_LED
+ * or EV_SND. The device is expected to carry out the requested
+ * action (turn on a LED, play sound, etc.) The call is protected
+ * by @event_lock and must not sleep
+ * @grab: input handle that currently has the device grabbed (via
+ * EVIOCGRAB ioctl). When a handle grabs a device it becomes sole
+ * recipient for all input events coming from the device
+ * @event_lock: this spinlock is is taken when input core receives
+ * and processes a new event for the device (in input_event()).
+ * Code that accesses and/or modifies parameters of a device
+ * (such as keymap or absmin, absmax, absfuzz, etc.) after device
+ * has been registered with input core must take this lock.
+ * @mutex: serializes calls to open(), close() and flush() methods
+ * @users: stores number of users (input handlers) that opened this
+ * device. It is used by input_open_device() and input_close_device()
+ * to make sure that dev->open() is only called when the first
+ * user opens device and dev->close() is called when the very
+ * last user closes the device
+ * @going_away: marks devices that are in a middle of unregistering and
+ * causes input_open_device*() fail with -ENODEV.
+ * @dev: driver model's view of this device
+ * @h_list: list of input handles associated with the device. When
+ * accessing the list dev->mutex must be held
+ * @node: used to place the device onto input_dev_list
+ */
struct input_dev {
- void *private;
+ void *private; /* do not use */
const char *name;
const char *phys;
@@ -955,8 +1028,6 @@
unsigned int repeat_key;
struct timer_list timer;
- int state;
-
int sync;
int abs[ABS_MAX + 1];
@@ -979,8 +1050,11 @@
struct input_handle *grab;
- struct mutex mutex; /* serializes open and close operations */
+ spinlock_t event_lock;
+ struct mutex mutex;
+
unsigned int users;
+ int going_away;
struct device dev;
union { /* temporarily so while we switching to struct device */
@@ -1046,7 +1120,9 @@
/**
* struct input_handler - implements one of interfaces for input devices
* @private: driver-specific data
- * @event: event handler
+ * @event: event handler. This method is being called by input core with
+ * interrupts disabled and dev->event_lock spinlock held and so
+ * it may not sleep
* @connect: called when attaching a handler to an input device
* @disconnect: disconnects a handler from input device
* @start: starts handler for given handle. This function is called by
@@ -1058,10 +1134,18 @@
* @name: name of the handler, to be shown in /proc/bus/input/handlers
* @id_table: pointer to a table of input_device_ids this driver can
* handle
- * @blacklist: prointer to a table of input_device_ids this driver should
+ * @blacklist: pointer to a table of input_device_ids this driver should
* ignore even if they match @id_table
* @h_list: list of input handles associated with the handler
* @node: for placing the driver onto input_handler_list
+ *
+ * Input handlers attach to input devices and create input handles. There
+ * are likely several handlers attached to any given input device at the
+ * same time. All of them will get their copy of input event generated by
+ * the device.
+ *
+ * Note that input core serializes calls to connect() and disconnect()
+ * methods.
*/
struct input_handler {
@@ -1083,6 +1167,18 @@
struct list_head node;
};
+/**
+ * struct input_handle - links input device with an input handler
+ * @private: handler-specific data
+ * @open: counter showing whether the handle is 'open', i.e. should deliver
+ * events from its device
+ * @name: name given to the handle by handler that created it
+ * @dev: input device the handle is attached to
+ * @handler: handler that works with the device through this handle
+ * @d_node: used to put the handle on device's list of attached handles
+ * @h_node: used to put the handle on handler's list of handles from which
+ * it gets events
+ */
struct input_handle {
void *private;
@@ -1205,7 +1301,7 @@
* @max_effects: maximum number of effects supported by device
* @effects: pointer to an array of effects currently loaded into device
* @effect_owners: array of effect owners; when file handle owning
- * an effect gets closed the effcet is automatically erased
+ * an effect gets closed the effect is automatically erased
*
* Every force-feedback device must implement upload() and playback()
* methods; erase() is optional. set_gain() and set_autocenter() need