diff options
| author | Colin Xu <colin.xu@intel.com> | 2021-02-02 03:19:23 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2021-02-23 15:52:59 +0300 |
| commit | a6829c350ec6bec47752826c9738122308e1588c (patch) | |
| tree | 03a3e48d1f56bc97ea4fed156d17841537a66f6a /drivers/virtio/virtio_input.c | |
| parent | d1e9aa9c34a776d43de819d3d334833aff5cca5a (diff) | |
| download | linux-a6829c350ec6bec47752826c9738122308e1588c.tar.xz | |
virtio_input: Prevent EV_MSC/MSC_TIMESTAMP loop storm for MT.
In 'commit 29cc309d8bf1 ("HID: hid-multitouch: forward MSC_TIMESTAMP")',
EV_MSC/MSC_TIMESTAMP is added to each before EV_SYN event. EV_MSC is
configured as INPUT_PASS_TO_ALL.
In case of a touch device which report MSC_TIMESTAMP:
BE pass EV_MSC/MSC_TIMESTAMP to FE on receiving event from evdev.
FE pass EV_MSC/MSC_TIMESTAMP back to BE.
BE writes EV_MSC/MSC_TIMESTAMP to evdev due to INPUT_PASS_TO_ALL.
BE receives extra EV_MSC/MSC_TIMESTAMP and pass to FE.
>>> Each new frame becomes larger and larger.
Disable EV_MSC/MSC_TIMESTAMP forwarding for MT.
V2: Rebase.
Signed-off-by: Colin Xu <colin.xu@intel.com>
Link: https://lore.kernel.org/r/20210202001923.6227-1-colin.xu@intel.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'drivers/virtio/virtio_input.c')
| -rw-r--r-- | drivers/virtio/virtio_input.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c index f1f6208edcf5..244965c20d9b 100644 --- a/drivers/virtio/virtio_input.c +++ b/drivers/virtio/virtio_input.c @@ -64,6 +64,21 @@ static int virtinput_send_status(struct virtio_input *vi, unsigned long flags; int rc; + /* + * Since 29cc309d8bf1 (HID: hid-multitouch: forward MSC_TIMESTAMP), + * EV_MSC/MSC_TIMESTAMP is added to each before EV_SYN event. + * EV_MSC is configured as INPUT_PASS_TO_ALL. + * In case of touch device: + * BE pass EV_MSC/MSC_TIMESTAMP to FE on receiving event from evdev. + * FE pass EV_MSC/MSC_TIMESTAMP back to BE. + * BE writes EV_MSC/MSC_TIMESTAMP to evdev due to INPUT_PASS_TO_ALL. + * BE receives extra EV_MSC/MSC_TIMESTAMP and pass to FE. + * >>> Each new frame becomes larger and larger. + * Disable EV_MSC/MSC_TIMESTAMP forwarding for MT. + */ + if (vi->idev->mt && type == EV_MSC && code == MSC_TIMESTAMP) + return 0; + stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC); if (!stsbuf) return -ENOMEM; |