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Input: use full RCU API

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RT guys alerted me to the fact that in their tree spinlocks
are preemptible and it is better to use full RCU API
(rcu_read_lock()/rcu_read_unlock()) to be safe.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Dmitry Torokhov 2007-10-13 15:46:55 -04:00
parent 70093178b6
commit 82ba56c273
4 changed files with 32 additions and 48 deletions
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22
drivers/input/evdev.c
View File

@ -63,10 +63,7 @@ static void evdev_pass_event(struct evdev_client *client,
}
/*
* Pass incoming event to all connected clients. Note that we are
* caleld under a spinlock with interrupts off so we don't need
* to use rcu_read_lock() here. Writers will be using syncronize_sched()
* instead of synchrnoize_rcu().
* Pass incoming event to all connected clients.
*/
static void evdev_event(struct input_handle *handle,
unsigned int type, unsigned int code, int value)
@ -80,6 +77,8 @@ static void evdev_event(struct input_handle *handle,
event.code = code;
event.value = value;
rcu_read_lock();
client = rcu_dereference(evdev->grab);
if (client)
evdev_pass_event(client, &event);
@ -87,6 +86,8 @@ static void evdev_event(struct input_handle *handle,
list_for_each_entry_rcu(client, &evdev->client_list, node)
evdev_pass_event(client, &event);
rcu_read_unlock();
wake_up_interruptible(&evdev->wait);
}
@ -142,12 +143,7 @@ static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
return error;
rcu_assign_pointer(evdev->grab, client);
/*
* We don't use synchronize_rcu() here because read-side
* critical section is protected by a spinlock instead
* of rcu_read_lock().
*/
synchronize_sched();
synchronize_rcu();
return 0;
}
@ -158,7 +154,7 @@ static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
return -EINVAL;
rcu_assign_pointer(evdev->grab, NULL);
synchronize_sched();
synchronize_rcu();
input_release_device(&evdev->handle);
return 0;
@ -170,7 +166,7 @@ static void evdev_attach_client(struct evdev *evdev,
spin_lock(&evdev->client_lock);
list_add_tail_rcu(&client->node, &evdev->client_list);
spin_unlock(&evdev->client_lock);
synchronize_sched();
synchronize_rcu();
}
static void evdev_detach_client(struct evdev *evdev,
@ -179,7 +175,7 @@ static void evdev_detach_client(struct evdev *evdev,
spin_lock(&evdev->client_lock);
list_del_rcu(&client->node);
spin_unlock(&evdev->client_lock);
synchronize_sched();
synchronize_rcu();
}
static int evdev_open_device(struct evdev *evdev)

36
drivers/input/input.c
View File

@ -65,16 +65,16 @@ static int input_defuzz_abs_event(int value, int old_val, int fuzz)
/*
* Pass event through all open handles. This function is called with
* dev->event_lock held and interrupts disabled. Because of that we
* do not need to use rcu_read_lock() here although we are using RCU
* to access handle list. Note that because of that write-side uses
* synchronize_sched() instead of synchronize_ru().
* dev->event_lock held and interrupts disabled.
*/
static void input_pass_event(struct input_dev *dev,
unsigned int type, unsigned int code, int value)
{
struct input_handle *handle = rcu_dereference(dev->grab);
struct input_handle *handle;
rcu_read_lock();
handle = rcu_dereference(dev->grab);
if (handle)
handle->handler->event(handle, type, code, value);
else
@ -82,6 +82,7 @@ static void input_pass_event(struct input_dev *dev,
if (handle->open)
handle->handler->event(handle,
type, code, value);
rcu_read_unlock();
}
/*
@ -293,9 +294,11 @@ void input_inject_event(struct input_handle *handle,
if (is_event_supported(type, dev->evbit, EV_MAX)) {
spin_lock_irqsave(&dev->event_lock, flags);
rcu_read_lock();
grab = rcu_dereference(dev->grab);
if (!grab || grab == handle)
input_handle_event(dev, type, code, value);
rcu_read_unlock();
spin_unlock_irqrestore(&dev->event_lock, flags);
}
@ -325,11 +328,7 @@ int input_grab_device(struct input_handle *handle)
}
rcu_assign_pointer(dev->grab, handle);
/*
* Not using synchronize_rcu() because read-side is protected
* by a spinlock with interrupts off instead of rcu_read_lock().
*/
synchronize_sched();
synchronize_rcu();
out:
mutex_unlock(&dev->mutex);
@ -344,7 +343,7 @@ static void __input_release_device(struct input_handle *handle)
if (dev->grab == handle) {
rcu_assign_pointer(dev->grab, NULL);
/* Make sure input_pass_event() notices that grab is gone */
synchronize_sched();
synchronize_rcu();
list_for_each_entry(handle, &dev->h_list, d_node)
if (handle->open && handle->handler->start)
@ -404,7 +403,7 @@ int input_open_device(struct input_handle *handle)
* Make sure we are not delivering any more events
* through this handle
*/
synchronize_sched();
synchronize_rcu();
}
}
@ -451,11 +450,11 @@ void input_close_device(struct input_handle *handle)
if (!--handle->open) {
/*
* synchronize_sched() makes sure that input_pass_event()
* synchronize_rcu() makes sure that input_pass_event()
* completed and that no more input events are delivered
* through this handle
*/
synchronize_sched();
synchronize_rcu();
}
mutex_unlock(&dev->mutex);
@ -1477,12 +1476,7 @@ int input_register_handle(struct input_handle *handle)
return error;
list_add_tail_rcu(&handle->d_node, &dev->h_list);
mutex_unlock(&dev->mutex);
/*
* We don't use synchronize_rcu() here because we rely
* on dev->event_lock to protect read-side critical
* section in input_pass_event().
*/
synchronize_sched();
synchronize_rcu();
/*
* Since we are supposed to be called from ->connect()
@ -1521,7 +1515,7 @@ void input_unregister_handle(struct input_handle *handle)
mutex_lock(&dev->mutex);
list_del_rcu(&handle->d_node);
mutex_unlock(&dev->mutex);
synchronize_sched();
synchronize_rcu();
}
EXPORT_SYMBOL(input_unregister_handle);

11
drivers/input/joydev.c
View File

@ -149,8 +149,10 @@ static void joydev_event(struct input_handle *handle,
event.time = jiffies_to_msecs(jiffies);
rcu_read_lock();
list_for_each_entry_rcu(client, &joydev->client_list, node)
joydev_pass_event(client, &event);
rcu_read_unlock();
wake_up_interruptible(&joydev->wait);
}
@ -178,12 +180,7 @@ static void joydev_attach_client(struct joydev *joydev,
spin_lock(&joydev->client_lock);
list_add_tail_rcu(&client->node, &joydev->client_list);
spin_unlock(&joydev->client_lock);
/*
* We don't use synchronize_rcu() here because read-side
* critical section is protected by a spinlock (dev->event_lock)
* instead of rcu_read_lock().
*/
synchronize_sched();
synchronize_rcu();
}
static void joydev_detach_client(struct joydev *joydev,
@ -192,7 +189,7 @@ static void joydev_detach_client(struct joydev *joydev,
spin_lock(&joydev->client_lock);
list_del_rcu(&client->node);
spin_unlock(&joydev->client_lock);
synchronize_sched();
synchronize_rcu();
}
static int joydev_open_device(struct joydev *joydev)

11
drivers/input/mousedev.c
View File

@ -265,6 +265,7 @@ static void mousedev_notify_readers(struct mousedev *mousedev,
unsigned int new_head;
int wake_readers = 0;
rcu_read_lock();
list_for_each_entry_rcu(client, &mousedev->client_list, node) {
/* Just acquire the lock, interrupts already disabled */
@ -309,6 +310,7 @@ static void mousedev_notify_readers(struct mousedev *mousedev,
wake_readers = 1;
}
}
rcu_read_unlock();
if (wake_readers)
wake_up_interruptible(&mousedev->wait);
@ -499,12 +501,7 @@ static void mousedev_attach_client(struct mousedev *mousedev,
spin_lock(&mousedev->client_lock);
list_add_tail_rcu(&client->node, &mousedev->client_list);
spin_unlock(&mousedev->client_lock);
/*
* We don't use synchronize_rcu() here because read-side
* critical section is protected by a spinlock (dev->event_lock)
* instead of rcu_read_lock().
*/
synchronize_sched();
synchronize_rcu();
}
static void mousedev_detach_client(struct mousedev *mousedev,
@ -513,7 +510,7 @@ static void mousedev_detach_client(struct mousedev *mousedev,
spin_lock(&mousedev->client_lock);
list_del_rcu(&client->node);
spin_unlock(&mousedev->client_lock);
synchronize_sched();
synchronize_rcu();
}
static int mousedev_release(struct inode *inode, struct file *file)