[PATCH xserver 1/2] Hold input lock for deviceProc

[Keith Packard]

This ensures that the deviceProc is never called while the input
thread is processing data from the device.

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 dix/devices.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/dix/devices.c b/dix/devices.c
index 9de84a6..56aae85 100644
--- a/dix/devices.c
+++ b/dix/devices.c
@@ -399,9 +399,11 @@ EnableDevice(DeviceIntPtr dev, BOOL sendevent)
         }
     }
 
+    input_lock();
     if ((*prev != dev) || !dev->inited ||
         ((ret = (*dev->deviceProc) (dev, DEVICE_ON)) != Success)) {
         ErrorF("[dix] couldn't enable device %d\n", dev->id);
+        input_unlock();
         return FALSE;
     }
     dev->enabled = TRUE;
@@ -410,6 +412,7 @@ EnableDevice(DeviceIntPtr dev, BOOL sendevent)
     for (prev = &inputInfo.devices; *prev; prev = &(*prev)->next);
     *prev = dev;
     dev->next = NULL;
+    input_unlock();
 
     enabled = TRUE;
     XIChangeDeviceProperty(dev, XIGetKnownProperty(XI_PROP_ENABLED),
@@ -488,20 +491,20 @@ DisableDevice(DeviceIntPtr dev, BOOL sendevent)
     if (dev->spriteInfo->paired)
         dev->spriteInfo->paired = NULL;
 
+    input_lock();
     (void) (*dev->deviceProc) (dev, DEVICE_OFF);
     dev->enabled = FALSE;
 
-    FreeSprite(dev);
-
     /* now that the device is disabled, we can reset the event reader's
      * last.slave */
-    input_lock();
     for (other = inputInfo.devices; other; other = other->next) {
         if (other->last.slave == dev)
             other->last.slave = NULL;
     }
     input_unlock();
 
+    FreeSprite(dev);
+
     LeaveWindow(dev);
     SetFocusOut(dev);
 
@@ -569,7 +572,9 @@ ActivateDevice(DeviceIntPtr dev, BOOL sendevent)
     if (!dev || !dev->deviceProc)
         return BadImplementation;
 
+    input_lock();
     ret = (*dev->deviceProc) (dev, DEVICE_INIT);
+    input_unlock();
     dev->inited = (ret == Success);
     if (!dev->inited)
         return ret;
@@ -935,6 +940,8 @@ FreeAllDeviceClasses(ClassesPtr classes)
  * enable it again and free associated structs. If you want the device to just
  * be disabled, DisableDevice().
  * Don't call this function directly, use RemoveDevice() instead.
+ *
+ * Called with input lock held.
  */
 static void
 CloseDevice(DeviceIntPtr dev)
@@ -1071,6 +1078,11 @@ void
 AbortDevices(void)
 {
     DeviceIntPtr dev;
+
+    /* Do not call input_lock as we don't know what
+     * state the input thread might be in, and that could
+     * cause a dead-lock.
+     */
     nt_list_for_each_entry(dev, inputInfo.devices, next) {
         if (!IsMaster(dev))
             (*dev->deviceProc) (dev, DEVICE_ABORT);
@@ -1135,6 +1147,8 @@ RemoveDevice(DeviceIntPtr dev, BOOL sendevent)
         flags[dev->id] = XIDeviceDisabled;
     }
 
+    input_lock();
+
     prev = NULL;
     for (tmp = inputInfo.devices; tmp; (prev = tmp), (tmp = next)) {
         next = tmp->next;
@@ -1167,6 +1181,8 @@ RemoveDevice(DeviceIntPtr dev, BOOL sendevent)
         }
     }
 
+    input_unlock();
+
     if (ret == Success && initialized) {
         inputInfo.numDevices--;
         SendDevicePresenceEvent(deviceid, DeviceRemoved);
-- 
2.8.1