[PATCH xserver] os: Lock input while messing with input device list

[Keith Packard]

The list of input devices may be changed by hotplugging while the
server is active, and those changes may come from either the main
thread or the input thread. That means the list of input devices needs
to be protected by a mutex.

This prevents input drivers from receiving I/O ready callbacks after
removing a device.

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 os/inputthread.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/os/inputthread.c b/os/inputthread.c
index 390b66b..40a0443 100644
--- a/os/inputthread.c
+++ b/os/inputthread.c
@@ -197,12 +197,14 @@ InputThreadRegisterDev(int fd,
     dev->readInputProc = readInputProc;
     dev->readInputArgs = readInputArgs;
 
+    input_lock();
     xorg_list_add(&dev->node, &inputThreadInfo->devs);
 
     FD_SET(fd, &inputThreadInfo->fds);
 
     InputThreadFillPipe(hotplugPipeWrite);
     DebugF("input-thread: registered device %d\n", fd);
+    input_unlock();
 
     return 1;
 }
@@ -228,6 +230,7 @@ InputThreadUnregisterDev(int fd)
         return 1;
     }
 
+    input_lock();
     xorg_list_for_each_entry(dev, &inputThreadInfo->devs, node)
         if (dev->fd == fd) {
             found_device = TRUE;
@@ -235,12 +238,17 @@ InputThreadUnregisterDev(int fd)
         }
 
     /* fd didn't match any registered device. */
-    if (!found_device)
+    if (!found_device) {
+        input_unlock();
         return 0;
+    }
 
     xorg_list_del(&dev->node);
 
     FD_CLR(fd, &inputThreadInfo->fds);
+
+    input_unlock();
+
     free(dev);
 
     InputThreadFillPipe(hotplugPipeWrite);
@@ -292,14 +300,14 @@ InputThreadDoWork(void *arg)
 
         DebugF("input-thread: %s generating events\n", __func__);
 
+        input_lock();
         /* Call the device drivers to generate input events for us */
         xorg_list_for_each_entry_safe(dev, next, &inputThreadInfo->devs, node) {
             if (FD_ISSET(dev->fd, &readyFds) && dev->readInputProc) {
-                input_lock();
                 dev->readInputProc(dev->fd, X_NOTIFY_READ, dev->readInputArgs);
-                input_unlock();
             }
         }
+        input_unlock();
 
         /* Kick main thread to process the generated input events and drain
          * events from hotplug pipe */
-- 
2.8.1