linux/net/rfkill/rfkill-input.c
Henrique de Moraes Holschuh 78236571a5 rfkill: rate-limit rfkill-input workqueue usage (v3)
Limit the number of "expensive" rfkill workqueue operations per second, in
order to not hog system resources too much when faced with a rogue source
of rfkill input events.

The old rfkill-input code (before it was refactored) had such a limit in
place.  It used to drop new events that were past the rate limit.  This
behaviour was not implemented as an anti-DoS measure, but rather as an
attempt to work around deficiencies in input device drivers which would
issue multiple KEY_FOO events too soon for a given key FOO (i.e. ones that
do not implement mechanical debouncing properly).

However, we can't really expect such issues to be worked around by every
input handler out there, and also by every userspace client of input
devices.  It is the input device driver's responsability to do debouncing
instead of spamming the input layer with bogus events.

The new limiter code is focused only on anti-DoS behaviour, and tries to
not lose events (instead, it coalesces them when possible).

The transmitters are updated once every 200ms, maximum.  Care is taken not
to delay a request to _enter_ rfkill transmitter Emergency Power Off (EPO)
mode.

If mistriggered (e.g. by a jiffies counter wrap), the code delays processing
*once* by 200ms.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-10-31 19:00:10 -04:00

460 lines
11 KiB
C

/*
* Input layer to RF Kill interface connector
*
* Copyright (c) 2007 Dmitry Torokhov
*/
/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/init.h>
#include <linux/rfkill.h>
#include <linux/sched.h>
#include "rfkill-input.h"
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION("Input layer to RF switch connector");
MODULE_LICENSE("GPL");
enum rfkill_input_master_mode {
RFKILL_INPUT_MASTER_DONOTHING = 0,
RFKILL_INPUT_MASTER_RESTORE = 1,
RFKILL_INPUT_MASTER_UNBLOCKALL = 2,
RFKILL_INPUT_MASTER_MAX, /* marker */
};
/* Delay (in ms) between consecutive switch ops */
#define RFKILL_OPS_DELAY 200
static enum rfkill_input_master_mode rfkill_master_switch_mode =
RFKILL_INPUT_MASTER_UNBLOCKALL;
module_param_named(master_switch_mode, rfkill_master_switch_mode, uint, 0);
MODULE_PARM_DESC(master_switch_mode,
"SW_RFKILL_ALL ON should: 0=do nothing; 1=restore; 2=unblock all");
enum rfkill_global_sched_op {
RFKILL_GLOBAL_OP_EPO = 0,
RFKILL_GLOBAL_OP_RESTORE,
RFKILL_GLOBAL_OP_UNLOCK,
RFKILL_GLOBAL_OP_UNBLOCK,
};
/*
* Currently, the code marked with RFKILL_NEED_SWSET is inactive.
* If handling of EV_SW SW_WLAN/WWAN/BLUETOOTH/etc is needed in the
* future, when such events are added, that code will be necessary.
*/
struct rfkill_task {
struct delayed_work dwork;
/* ensures that task is serialized */
struct mutex mutex;
/* protects everything below */
spinlock_t lock;
/* pending regular switch operations (1=pending) */
unsigned long sw_pending[BITS_TO_LONGS(RFKILL_TYPE_MAX)];
#ifdef RFKILL_NEED_SWSET
/* set operation pending (1=pending) */
unsigned long sw_setpending[BITS_TO_LONGS(RFKILL_TYPE_MAX)];
/* desired state for pending set operation (1=unblock) */
unsigned long sw_newstate[BITS_TO_LONGS(RFKILL_TYPE_MAX)];
#endif
/* should the state be complemented (1=yes) */
unsigned long sw_togglestate[BITS_TO_LONGS(RFKILL_TYPE_MAX)];
bool global_op_pending;
enum rfkill_global_sched_op op;
/* last time it was scheduled */
unsigned long last_scheduled;
};
static void __rfkill_handle_global_op(enum rfkill_global_sched_op op)
{
unsigned int i;
switch (op) {
case RFKILL_GLOBAL_OP_EPO:
rfkill_epo();
break;
case RFKILL_GLOBAL_OP_RESTORE:
rfkill_restore_states();
break;
case RFKILL_GLOBAL_OP_UNLOCK:
rfkill_remove_epo_lock();
break;
case RFKILL_GLOBAL_OP_UNBLOCK:
rfkill_remove_epo_lock();
for (i = 0; i < RFKILL_TYPE_MAX; i++)
rfkill_switch_all(i, RFKILL_STATE_UNBLOCKED);
break;
default:
/* memory corruption or bug, fail safely */
rfkill_epo();
WARN(1, "Unknown requested operation %d! "
"rfkill Emergency Power Off activated\n",
op);
}
}
#ifdef RFKILL_NEED_SWSET
static void __rfkill_handle_normal_op(const enum rfkill_type type,
const bool sp, const bool s, const bool c)
{
enum rfkill_state state;
if (sp)
state = (s) ? RFKILL_STATE_UNBLOCKED :
RFKILL_STATE_SOFT_BLOCKED;
else
state = rfkill_get_global_state(type);
if (c)
state = rfkill_state_complement(state);
rfkill_switch_all(type, state);
}
#else
static void __rfkill_handle_normal_op(const enum rfkill_type type,
const bool c)
{
enum rfkill_state state;
state = rfkill_get_global_state(type);
if (c)
state = rfkill_state_complement(state);
rfkill_switch_all(type, state);
}
#endif
static void rfkill_task_handler(struct work_struct *work)
{
struct rfkill_task *task = container_of(work,
struct rfkill_task, dwork.work);
bool doit = true;
mutex_lock(&task->mutex);
spin_lock_irq(&task->lock);
while (doit) {
if (task->global_op_pending) {
enum rfkill_global_sched_op op = task->op;
task->global_op_pending = false;
memset(task->sw_pending, 0, sizeof(task->sw_pending));
spin_unlock_irq(&task->lock);
__rfkill_handle_global_op(op);
/* make sure we do at least one pass with
* !task->global_op_pending */
spin_lock_irq(&task->lock);
continue;
} else if (!rfkill_is_epo_lock_active()) {
unsigned int i = 0;
while (!task->global_op_pending &&
i < RFKILL_TYPE_MAX) {
if (test_and_clear_bit(i, task->sw_pending)) {
bool c;
#ifdef RFKILL_NEED_SWSET
bool sp, s;
sp = test_and_clear_bit(i,
task->sw_setpending);
s = test_bit(i, task->sw_newstate);
#endif
c = test_and_clear_bit(i,
task->sw_togglestate);
spin_unlock_irq(&task->lock);
#ifdef RFKILL_NEED_SWSET
__rfkill_handle_normal_op(i, sp, s, c);
#else
__rfkill_handle_normal_op(i, c);
#endif
spin_lock_irq(&task->lock);
}
i++;
}
}
doit = task->global_op_pending;
}
spin_unlock_irq(&task->lock);
mutex_unlock(&task->mutex);
}
static struct rfkill_task rfkill_task = {
.dwork = __DELAYED_WORK_INITIALIZER(rfkill_task.dwork,
rfkill_task_handler),
.mutex = __MUTEX_INITIALIZER(rfkill_task.mutex),
.lock = __SPIN_LOCK_UNLOCKED(rfkill_task.lock),
};
static unsigned long rfkill_ratelimit(const unsigned long last)
{
const unsigned long delay = msecs_to_jiffies(RFKILL_OPS_DELAY);
return (time_after(jiffies, last + delay)) ? 0 : delay;
}
static void rfkill_schedule_ratelimited(void)
{
if (!delayed_work_pending(&rfkill_task.dwork)) {
schedule_delayed_work(&rfkill_task.dwork,
rfkill_ratelimit(rfkill_task.last_scheduled));
rfkill_task.last_scheduled = jiffies;
}
}
static void rfkill_schedule_global_op(enum rfkill_global_sched_op op)
{
unsigned long flags;
spin_lock_irqsave(&rfkill_task.lock, flags);
rfkill_task.op = op;
rfkill_task.global_op_pending = true;
if (op == RFKILL_GLOBAL_OP_EPO && !rfkill_is_epo_lock_active()) {
/* bypass the limiter for EPO */
cancel_delayed_work(&rfkill_task.dwork);
schedule_delayed_work(&rfkill_task.dwork, 0);
rfkill_task.last_scheduled = jiffies;
} else
rfkill_schedule_ratelimited();
spin_unlock_irqrestore(&rfkill_task.lock, flags);
}
#ifdef RFKILL_NEED_SWSET
/* Use this if you need to add EV_SW SW_WLAN/WWAN/BLUETOOTH/etc handling */
static void rfkill_schedule_set(enum rfkill_type type,
enum rfkill_state desired_state)
{
unsigned long flags;
if (rfkill_is_epo_lock_active())
return;
spin_lock_irqsave(&rfkill_task.lock, flags);
if (!rfkill_task.global_op_pending) {
set_bit(type, rfkill_task.sw_pending);
set_bit(type, rfkill_task.sw_setpending);
clear_bit(type, rfkill_task.sw_togglestate);
if (desired_state)
set_bit(type, rfkill_task.sw_newstate);
else
clear_bit(type, rfkill_task.sw_newstate);
rfkill_schedule_ratelimited();
}
spin_unlock_irqrestore(&rfkill_task.lock, flags);
}
#endif
static void rfkill_schedule_toggle(enum rfkill_type type)
{
unsigned long flags;
if (rfkill_is_epo_lock_active())
return;
spin_lock_irqsave(&rfkill_task.lock, flags);
if (!rfkill_task.global_op_pending) {
set_bit(type, rfkill_task.sw_pending);
change_bit(type, rfkill_task.sw_togglestate);
rfkill_schedule_ratelimited();
}
spin_unlock_irqrestore(&rfkill_task.lock, flags);
}
static void rfkill_schedule_evsw_rfkillall(int state)
{
if (state) {
switch (rfkill_master_switch_mode) {
case RFKILL_INPUT_MASTER_UNBLOCKALL:
rfkill_schedule_global_op(RFKILL_GLOBAL_OP_UNBLOCK);
break;
case RFKILL_INPUT_MASTER_RESTORE:
rfkill_schedule_global_op(RFKILL_GLOBAL_OP_RESTORE);
break;
case RFKILL_INPUT_MASTER_DONOTHING:
rfkill_schedule_global_op(RFKILL_GLOBAL_OP_UNLOCK);
break;
default:
/* memory corruption or driver bug! fail safely */
rfkill_schedule_global_op(RFKILL_GLOBAL_OP_EPO);
WARN(1, "Unknown rfkill_master_switch_mode (%d), "
"driver bug or memory corruption detected!\n",
rfkill_master_switch_mode);
break;
}
} else
rfkill_schedule_global_op(RFKILL_GLOBAL_OP_EPO);
}
static void rfkill_event(struct input_handle *handle, unsigned int type,
unsigned int code, int data)
{
if (type == EV_KEY && data == 1) {
enum rfkill_type t;
switch (code) {
case KEY_WLAN:
t = RFKILL_TYPE_WLAN;
break;
case KEY_BLUETOOTH:
t = RFKILL_TYPE_BLUETOOTH;
break;
case KEY_UWB:
t = RFKILL_TYPE_UWB;
break;
case KEY_WIMAX:
t = RFKILL_TYPE_WIMAX;
break;
default:
return;
}
rfkill_schedule_toggle(t);
return;
} else if (type == EV_SW) {
switch (code) {
case SW_RFKILL_ALL:
rfkill_schedule_evsw_rfkillall(data);
return;
default:
return;
}
}
}
static int rfkill_connect(struct input_handler *handler, struct input_dev *dev,
const struct input_device_id *id)
{
struct input_handle *handle;
int error;
handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
if (!handle)
return -ENOMEM;
handle->dev = dev;
handle->handler = handler;
handle->name = "rfkill";
/* causes rfkill_start() to be called */
error = input_register_handle(handle);
if (error)
goto err_free_handle;
error = input_open_device(handle);
if (error)
goto err_unregister_handle;
return 0;
err_unregister_handle:
input_unregister_handle(handle);
err_free_handle:
kfree(handle);
return error;
}
static void rfkill_start(struct input_handle *handle)
{
/* Take event_lock to guard against configuration changes, we
* should be able to deal with concurrency with rfkill_event()
* just fine (which event_lock will also avoid). */
spin_lock_irq(&handle->dev->event_lock);
if (test_bit(EV_SW, handle->dev->evbit)) {
if (test_bit(SW_RFKILL_ALL, handle->dev->swbit))
rfkill_schedule_evsw_rfkillall(test_bit(SW_RFKILL_ALL,
handle->dev->sw));
/* add resync for further EV_SW events here */
}
spin_unlock_irq(&handle->dev->event_lock);
}
static void rfkill_disconnect(struct input_handle *handle)
{
input_close_device(handle);
input_unregister_handle(handle);
kfree(handle);
}
static const struct input_device_id rfkill_ids[] = {
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
.evbit = { BIT_MASK(EV_KEY) },
.keybit = { [BIT_WORD(KEY_WLAN)] = BIT_MASK(KEY_WLAN) },
},
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
.evbit = { BIT_MASK(EV_KEY) },
.keybit = { [BIT_WORD(KEY_BLUETOOTH)] = BIT_MASK(KEY_BLUETOOTH) },
},
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
.evbit = { BIT_MASK(EV_KEY) },
.keybit = { [BIT_WORD(KEY_UWB)] = BIT_MASK(KEY_UWB) },
},
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
.evbit = { BIT_MASK(EV_KEY) },
.keybit = { [BIT_WORD(KEY_WIMAX)] = BIT_MASK(KEY_WIMAX) },
},
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_SWBIT,
.evbit = { BIT(EV_SW) },
.swbit = { [BIT_WORD(SW_RFKILL_ALL)] = BIT_MASK(SW_RFKILL_ALL) },
},
{ }
};
static struct input_handler rfkill_handler = {
.event = rfkill_event,
.connect = rfkill_connect,
.disconnect = rfkill_disconnect,
.start = rfkill_start,
.name = "rfkill",
.id_table = rfkill_ids,
};
static int __init rfkill_handler_init(void)
{
if (rfkill_master_switch_mode >= RFKILL_INPUT_MASTER_MAX)
return -EINVAL;
/*
* The penalty to not doing this is a possible RFKILL_OPS_DELAY delay
* at the first use. Acceptable, but if we can avoid it, why not?
*/
rfkill_task.last_scheduled =
jiffies - msecs_to_jiffies(RFKILL_OPS_DELAY) - 1;
return input_register_handler(&rfkill_handler);
}
static void __exit rfkill_handler_exit(void)
{
input_unregister_handler(&rfkill_handler);
cancel_delayed_work_sync(&rfkill_task.dwork);
rfkill_remove_epo_lock();
}
module_init(rfkill_handler_init);
module_exit(rfkill_handler_exit);