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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2017-09-01 17:13:43 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2017-09-21 16:31:22 -0700
commite8b95728f724797f958912fd9b765a695595d3a6 (patch)
tree0d3f91f4dc14bf8eb728def1697283cce9177aab /include
parentbbc8608755da42e7494c00dce24a636007972def (diff)
Input: uinput - avoid FF flush when destroying device
Normally, when input device supporting force feedback effects is being destroyed, we try to "flush" currently playing effects, so that the physical device does not continue vibrating (or executing other effects). Unfortunately this does not work well for uinput as flushing of the effects deadlocks with the destroy action: - if device is being destroyed because the file descriptor is being closed, then there is noone to even service FF requests; - if device is being destroyed because userspace sent UI_DEV_DESTROY, while theoretically it could be possible to service FF requests, userspace is unlikely to do so (they'd need to make sure FF handling happens on a separate thread) even if kernel solves the issue with FF ioctls deadlocking with UI_DEV_DESTROY ioctl on udev->mutex. To avoid lockups like the one below, let's install a custom input device flush handler, and avoid trying to flush force feedback effects when we destroying the device, and instead rely on uinput to shut off the device properly. NMI watchdog: Watchdog detected hard LOCKUP on cpu 3 ... <<EOE>> [<ffffffff817a0307>] _raw_spin_lock_irqsave+0x37/0x40 [<ffffffff810e633d>] complete+0x1d/0x50 [<ffffffffa00ba08c>] uinput_request_done+0x3c/0x40 [uinput] [<ffffffffa00ba587>] uinput_request_submit.part.7+0x47/0xb0 [uinput] [<ffffffffa00bb62b>] uinput_dev_erase_effect+0x5b/0x76 [uinput] [<ffffffff815d91ad>] erase_effect+0xad/0xf0 [<ffffffff815d929d>] flush_effects+0x4d/0x90 [<ffffffff815d4cc0>] input_flush_device+0x40/0x60 [<ffffffff815daf1c>] evdev_cleanup+0xac/0xc0 [<ffffffff815daf5b>] evdev_disconnect+0x2b/0x60 [<ffffffff815d74ac>] __input_unregister_device+0xac/0x150 [<ffffffff815d75f7>] input_unregister_device+0x47/0x70 [<ffffffffa00bac45>] uinput_destroy_device+0xb5/0xc0 [uinput] [<ffffffffa00bb2de>] uinput_ioctl_handler.isra.9+0x65e/0x740 [uinput] [<ffffffff811231ab>] ? do_futex+0x12b/0xad0 [<ffffffffa00bb3f8>] uinput_ioctl+0x18/0x20 [uinput] [<ffffffff81241248>] do_vfs_ioctl+0x298/0x480 [<ffffffff81337553>] ? security_file_ioctl+0x43/0x60 [<ffffffff812414a9>] SyS_ioctl+0x79/0x90 [<ffffffff817a04ee>] entry_SYSCALL_64_fastpath+0x12/0x71 Reported-by: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com> Reported-by: Clément VUCHENER <clement.vuchener@gmail.com> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=193741 Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/input.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/input.h b/include/linux/input.h
index a65e3b24fb18..fb5e23c7ed98 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -529,6 +529,7 @@ int input_ff_event(struct input_dev *dev, unsigned int type, unsigned int code,
int input_ff_upload(struct input_dev *dev, struct ff_effect *effect, struct file *file);
int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file);
+int input_ff_flush(struct input_dev *dev, struct file *file);
int input_ff_create_memless(struct input_dev *dev, void *data,
int (*play_effect)(struct input_dev *, void *, struct ff_effect *));