The destruction of a input device in uinput is triggered by an ioctl(). If
a process tries to destroy an input device while other is uploading a
force feedback effect by evdev to the same device, they'll deadlock:
uinput-driver D ffff88001f994540 3120 2403 2374
ffff88001dc459e8 0000000000000046 ffff88001dc45988 ffffffff8106a2d8
ffffffff81a4a980 ffffffff81a4a980 ffff88001f994540 ffff88001ea3c540
ffff88001f9948e0 00000000810297b8 0000000100000001 ffff88001f9948e0
Call Trace:
[<ffffffff8106a2d8>] ? __lock_acquire+0xb3a/0xc01
[<ffffffff81068a7b>] ? mark_lock+0x22/0x3a2
[<ffffffff81068e62>] ? mark_held_locks+0x67/0x82
[<ffffffff813148c6>] ? __mutex_lock_common+0x1f0/0x35d
[<ffffffff813148d6>] __mutex_lock_common+0x200/0x35d
[<ffffffff81251699>] ? evdev_cleanup+0x2f/0x103
[<ffffffff8106763a>] ? lock_release_holdtime+0x2c/0x111
[<ffffffff81251699>] ? evdev_cleanup+0x2f/0x103
[<ffffffff81158b16>] ? kobject_put+0x47/0x4b
[<ffffffff81314adc>] mutex_lock_nested+0x35/0x3a
[<ffffffff81251699>] evdev_cleanup+0x2f/0x103
[<ffffffff81251798>] evdev_disconnect+0x2b/0x44
[<ffffffff8124cc02>] input_unregister_device+0x11a/0x1c9
[<ffffffff81258505>] uinput_destroy_device+0x2d/0x5d
[<ffffffff8125854d>] uinput_release+0x18/0x26
[<ffffffff810cc5b9>] __fput+0xf0/0x18b
[<ffffffff810cc669>] fput+0x15/0x17
[<ffffffff810c99f8>] filp_close+0x67/0x72
[<ffffffff81049255>] put_files_struct+0x74/0xc8
[<ffffffff810492f0>] exit_files+0x47/0x4f
[<ffffffff8104ab49>] do_exit+0x228/0x89b
[<ffffffff81316002>] ? _spin_unlock_irq+0x2b/0x37
[<ffffffff8104b235>] do_group_exit+0x79/0xa9
[<ffffffff81054a37>] get_signal_to_deliver+0x318/0x339
[<ffffffff810103fb>] do_notify_resume+0x8c/0x875
[<ffffffff8106763a>] ? lock_release_holdtime+0x2c/0x111
[<ffffffff81316002>] ? _spin_unlock_irq+0x2b/0x37
[<ffffffff81069007>] ? trace_hardirqs_on_caller+0xf6/0x11a
[<ffffffff81069038>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81316002>] ? _spin_unlock_irq+0x2b/0x37
[<ffffffff81043f97>] ? finish_task_switch+0x5f/0xc2
[<ffffffff81043f38>] ? finish_task_switch+0x0/0xc2
[<ffffffff810d71e2>] ? do_vfs_ioctl+0x398/0x3c6
[<ffffffff810119af>] ? retint_signal+0x11/0xc2
[<ffffffff81069007>] ? trace_hardirqs_on_caller+0xf6/0x11a
[<ffffffff81011a03>] retint_signal+0x65/0xc2
uinput-app D 0000000000000002 3120 2413 2374
ffff88001d941be8 0000000000000046 ffff88001d941b38 ffffffff81068a7b
ffffffff81a4a980 ffffffff81a4a980 ffff88001d96a2a0 ffff88001f994540
ffff88001d96a640 000000000000004e ffff88001d941bc8 ffff88001d96a640
Call Trace:
[<ffffffff81068a7b>] ? mark_lock+0x22/0x3a2
[<ffffffff810297b8>] ? pvclock_clocksource_read+0x42/0x7e
[<ffffffff81068a7b>] ? mark_lock+0x22/0x3a2
[<ffffffff813142c6>] schedule_timeout+0x22/0xc6
[<ffffffff81316002>] ? _spin_unlock_irq+0x2b/0x37
[<ffffffff81069007>] ? trace_hardirqs_on_caller+0xf6/0x11a
[<ffffffff81069038>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81316002>] ? _spin_unlock_irq+0x2b/0x37
[<ffffffff813141a2>] wait_for_common+0xb7/0x100
[<ffffffff8103fcde>] ? default_wake_function+0x0/0xf
[<ffffffff81314275>] wait_for_completion+0x18/0x1a
[<ffffffff81258acf>] uinput_dev_upload_effect+0x80/0x93
[<ffffffff8124e6d1>] input_ff_upload+0x1eb/0x276
[<ffffffff8125130f>] evdev_ioctl_handler+0x6f1/0x709
[<ffffffff81017a68>] ? sched_clock+0x9/0xc
[<ffffffff8106763a>] ? lock_release_holdtime+0x2c/0x111
[<ffffffff81251344>] evdev_ioctl+0xb/0xd
[<ffffffff810d6dfc>] vfs_ioctl+0x2a/0x78
[<ffffffff810d71e2>] do_vfs_ioctl+0x398/0x3c6
[<ffffffff810cb067>] ? fsnotify_modify+0x62/0x6a
[<ffffffff810110ca>] ? sysret_check+0x46/0x81
[<ffffffff810d7252>] sys_ioctl+0x42/0x65
[<ffffffff8101107a>] system_call_fastpath+0x16/0x1b
This patch fixes the problem by flushing all pending FF uploads before
destroying the device and preventing new uploads during this operation
Signed-off-by: Aristeu Rozanski <aris@xxxxxxxxxx>
---
drivers/input/misc/uinput.c | 41 +++++++++++++++++++++++++++++++++++++----
include/linux/uinput.h | 1 +
2 files changed, 38 insertions(+), 4 deletions(-)
--- a/drivers/input/misc/uinput.c 2009-02-13 19:21:24.000000000 -0500
+++ b/drivers/input/misc/uinput.c 2009-02-13 19:21:30.000000000 -0500
@@ -61,6 +61,9 @@ static int uinput_request_alloc_id(struc
spin_lock(&udev->requests_lock);
+ if (unlikely(udev->requests_flushed))
+ goto out;
+
for (id = 0; id < UINPUT_NUM_REQUESTS; id++)
if (!udev->requests[id]) {
request->id = id;
@@ -69,6 +72,7 @@ static int uinput_request_alloc_id(struc
break;
}
+out:
spin_unlock(&udev->requests_lock);
return err;
}
@@ -107,6 +111,34 @@ static int uinput_request_submit(struct
return request->retval;
}
+static inline void uinput_init_requests(struct uinput_device *udev)
+{
+ spin_lock_init(&udev->requests_lock);
+ init_waitqueue_head(&udev->requests_waitq);
+ udev->requests_flushed = 0;
+}
+
+static void uinput_flush_requests(struct uinput_device *udev)
+{
+ struct uinput_request *request;
+ int id;
+
+ /*
+ * get rid of all pending requests and set requests_flushed to prevent
+ * more requests to be filled until we unregister the input device
+ */
+ spin_lock(&udev->requests_lock);
+ udev->requests_flushed = 1;
+ for (id = 0; id < UINPUT_NUM_REQUESTS; id++) {
+ request = udev->requests[id];
+ if (request == NULL)
+ continue;
+ request->retval = -ENODEV;
+ uinput_request_done(udev, request);
+ }
+ spin_unlock(&udev->requests_lock);
+}
+
static void uinput_dev_set_gain(struct input_dev *dev, u16 gain)
{
uinput_dev_event(dev, EV_FF, FF_GAIN, gain);
@@ -167,9 +199,11 @@ static void uinput_destroy_device(struct
if (udev->dev) {
name = udev->dev->name;
phys = udev->dev->phys;
- if (udev->state == UIST_CREATED)
+ if (udev->state == UIST_CREATED) {
+ uinput_flush_requests(udev);
input_unregister_device(udev->dev);
- else
+ uinput_init_requests(udev);
+ } else
input_free_device(udev->dev);
kfree(name);
kfree(phys);
@@ -224,8 +258,7 @@ static int uinput_open(struct inode *ino
lock_kernel();
mutex_init(&newdev->mutex);
- spin_lock_init(&newdev->requests_lock);
- init_waitqueue_head(&newdev->requests_waitq);
+ uinput_init_requests(newdev);
init_waitqueue_head(&newdev->waitq);
newdev->state = UIST_NEW_DEVICE;
--- a/include/linux/uinput.h 2009-02-13 19:21:24.000000000 -0500
+++ b/include/linux/uinput.h 2009-02-13 19:21:30.000000000 -0500
@@ -74,6 +74,7 @@ struct uinput_device {
struct uinput_request *requests[UINPUT_NUM_REQUESTS];
wait_queue_head_t requests_waitq;
spinlock_t requests_lock;
+ int requests_flushed;
};
#endif /* __KERNEL__ */
--
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