[PATCH RFC xf86-input-libinput] Swap the registered input device on DEVICE_OFF when needed
Peter Hutterer
peter.hutterer at who-t.net
Fri Oct 14 07:13:52 UTC 2016
If we don't swap out the pInfo previously passed to xf86AddEnabledDevice(),
the thread eventually calls read_input on a struct that has been deleted.
Avoid this by swapping out the to-be-destroyed pInfo with the first one we
find.
FIXME: incomplete, this doesn't do any driver checking.
Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
Hans: I'm not a big fan of copying the fields into our custom InputInfoRec,
it makes the inner workings of xf86AddEnabledDevice() and the thread
effectively input driver ABI. This one is a slightly nicer (yet incomplete)
solution, what do you think?
src/xf86libinput.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/src/xf86libinput.c b/src/xf86libinput.c
index 69f7ae3..dcd3018 100644
--- a/src/xf86libinput.c
+++ b/src/xf86libinput.c
@@ -87,6 +87,7 @@
struct xf86libinput_driver {
struct libinput *libinput;
int device_enabled_count;
+ void *registered_InputInfoPtr;
};
static struct xf86libinput_driver driver_context;
@@ -583,6 +584,7 @@ xf86libinput_on(DeviceIntPtr dev)
if (driver_context.device_enabled_count == 0) {
#if HAVE_THREADED_INPUT
xf86AddEnabledDevice(pInfo);
+ driver_context.registered_InputInfoPtr = pInfo;
#else
/* Can't use xf86AddEnabledDevice on an epollfd */
AddEnabledDevice(pInfo->fd);
@@ -1138,6 +1140,28 @@ xf86libinput_destroy(DeviceIntPtr dev)
struct xf86libinput *driver_data = pInfo->private;
struct xf86libinput_device *shared_device = driver_data->shared_device;
+ /* If the device being destroyed is the one we used for
+ * xf86AddEnabledDevice(), we need to swap it out for one that is
+ * still live. xf86AddEnabledDevice() buffers some data and once the
+ * deletes pInfo (when DEVICE_OFF completes) the thread will keep
+ * calling that struct's read_input because we never removed it.
+ * Avoid this by removing ours and substituting one that's still
+ * valid, the fd is the same anyway (libinput's epollfd).
+ */
+ if (pInfo == driver_context.registered_InputInfoPtr &&
+ driver_context.device_enabled_count > 0) {
+ InputInfoPtr next = xf86FirstLocalDevice();
+ while (next == pInfo)
+ next = pInfo->next;
+
+ input_lock();
+ xf86RemoveEnabledDevice(pInfo);
+ if (next) /* shouldn't ever be NULL anyway */
+ xf86AddEnabledDevice(next);
+ driver_context.registered_InputInfoPtr = next;
+ input_unlock();
+ }
+
xorg_list_del(&driver_data->shared_device_link);
if (driver_data->tablet_tool)
--
2.7.4
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