[PATCH xserver 3/6] Create a threaded mechanism for input

Keith Packard keithp at keithp.com
Tue Dec 8 15:44:51 PST 2015


The current SIGIO signal handler method, used at generation of input events,
has a bunch of oddities. This patch introduces an alternative way using a
thread, which is used to select()s all input device file descriptors.

A mutex was used to control the access to input structures by the main and input
threads. Two pipes to emit alert events (such hotplug ones) and guarantee the
proper communication between them was also used.

Co-authored-by: Fernando Carrijo <fcarrijo at freedesktop.org>
Signed-off-by: Tiago Vignatti <tiago.vignatti at nokia.com>

v2: Fix non-Xorg link, and disable by default on non-Linux

This also splits out the actual enabling of input threads to
DDX-specific patches which follow

Signed-off-by: Adam Jackson <ajax at redhat.com>
Signed-off-by: Keith Packard <keithp at keithp.com>
---
 configure.ac          |  29 ++++
 dix/globals.c         |   2 +
 dix/main.c            |  15 +-
 include/Makefile.am   |   1 +
 include/input.h       |   9 ++
 include/inputthread.h |  45 ++++++
 include/misc.h        |   1 +
 mi/mieq.c             |  46 +-----
 os/Makefile.am        |   1 +
 os/inputthread.c      | 381 ++++++++++++++++++++++++++++++++++++++++++++++++++
 os/utils.c            |   7 +-
 11 files changed, 482 insertions(+), 55 deletions(-)
 create mode 100644 include/inputthread.h
 create mode 100644 os/inputthread.c

diff --git a/configure.ac b/configure.ac
index 2e38efa..46a645e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -828,6 +828,35 @@ SDK_REQUIRED_MODULES="$XPROTO $RANDRPROTO $RENDERPROTO $XEXTPROTO $INPUTPROTO $K
 # Make SDK_REQUIRED_MODULES available for inclusion in xorg-server.pc
 AC_SUBST(SDK_REQUIRED_MODULES)
 
+# input thread setup
+case $host_os in
+linux*)
+	THREAD_DEFAULT=yes ;;
+*)
+	THREAD_DEFAULT=no ;;
+esac
+AC_ARG_ENABLE(input-thread, AS_HELP_STRING([--enable-input-thread],
+	     [Enable input threads]),
+	     [INPUTTHREAD=$enableval], [INPUTTHREAD=$THREAD_DEFAULT])
+if test "x$INPUTTHREAD" = "xyes" ; then
+    case $host_os in
+    linux*|openbsd*|gnu*|k*bsd*-gnu)
+	    THREAD_LIB=-lpthread ;;
+    netbsd*)
+	    THREAD_CFLAGS="-D_POSIX_THREAD_SAFE_FUNCTIONS"
+	    THREAD_LIB="-lpthread" ;;
+    freebsd*)
+	    THREAD_CFLAGS="-D_THREAD_SAFE"
+	    THREAD_LIB="-pthread" ;;
+    dragonfly*)
+	    THREAD_LIB="-pthread" ;;
+    solaris*)
+	    THREAD_CFLAGS="-D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS" ;;
+    esac
+    SYS_LIBS="$SYS_LIBS $THREAD_LIB"
+    CFLAGS="$CFLAGS $THREAD_CFLAGS"
+fi
+
 REQUIRED_MODULES="$FIXESPROTO $DAMAGEPROTO $XCMISCPROTO $XTRANS $BIGREQSPROTO $SDK_REQUIRED_MODULES"
 
 dnl systemd socket activation
diff --git a/dix/globals.c b/dix/globals.c
index f36a938..9d81364 100644
--- a/dix/globals.c
+++ b/dix/globals.c
@@ -132,3 +132,5 @@ Bool explicit_display = FALSE;
 char *ConnectionInfo;
 
 CARD32 TimeOutValue = DEFAULT_TIMEOUT * MILLI_PER_SECOND;
+
+pthread_mutex_t input_mutex = PTHREAD_MUTEX_INITIALIZER;
diff --git a/dix/main.c b/dix/main.c
index 661ab03..bc2eed0 100644
--- a/dix/main.c
+++ b/dix/main.c
@@ -120,15 +120,10 @@ Equipment Corporation.
 
 extern void Dispatch(void);
 
-#ifdef XQUARTZ
-#include <pthread.h>
-
-BOOL serverRunning = FALSE;
+Bool serverRunning;
 pthread_mutex_t serverRunningMutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t serverRunningCond = PTHREAD_COND_INITIALIZER;
 
-#endif
-
 int
 dix_main(int argc, char *argv[], char *envp[])
 {
@@ -286,24 +281,22 @@ dix_main(int argc, char *argv[], char *envp[])
             }
         }
 
-#ifdef XQUARTZ
         /* Let the other threads know the server is done with its init */
         pthread_mutex_lock(&serverRunningMutex);
         serverRunning = TRUE;
         pthread_cond_broadcast(&serverRunningCond);
         pthread_mutex_unlock(&serverRunningMutex);
-#endif
 
         NotifyParentProcess();
 
+	InputThreadInit();
+
         Dispatch();
 
-#ifdef XQUARTZ
         /* Let the other threads know the server is no longer running */
         pthread_mutex_lock(&serverRunningMutex);
         serverRunning = FALSE;
         pthread_mutex_unlock(&serverRunningMutex);
-#endif
 
         UndisplayDevices();
         DisableAllDevices();
@@ -328,6 +321,8 @@ dix_main(int argc, char *argv[], char *envp[])
 
         CloseInput();
 
+        InputThreadFini();
+
         for (i = 0; i < screenInfo.numScreens; i++)
             screenInfo.screens[i]->root = NullWindow;
 
diff --git a/include/Makefile.am b/include/Makefile.am
index 70b83ff..cd56447 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -71,6 +71,7 @@ EXTRA_DIST = 	\
 	dix-config-apple-verbatim.h \
 	dixfontstubs.h eventconvert.h eventstr.h inpututils.h \
 	probes.h \
+	inputthread.h \
 	protocol-versions.h \
 	swaprep.h \
 	swapreq.h \
diff --git a/include/input.h b/include/input.h
index 5bc60f0..abb7a49 100644
--- a/include/input.h
+++ b/include/input.h
@@ -56,6 +56,7 @@ SOFTWARE.
 #include "xkbrules.h"
 #include "events.h"
 #include "list.h"
+#include "inputthread.h"
 #include <X11/extensions/XI2.h>
 
 #define DEVICE_INIT	0
@@ -712,10 +713,18 @@ extern _X_HIDDEN void input_constrain_cursor(DeviceIntPtr pDev, ScreenPtr screen
                                              int *out_x, int *out_y,
                                              int *nevents, InternalEvent* events);
 
+extern _X_EXPORT pthread_mutex_t input_mutex;
+
 static inline void input_lock(void) {
+    pthread_mutex_lock(&input_mutex);
 }
 
 static inline void input_unlock(void) {
+    pthread_mutex_unlock(&input_mutex);
 }
 
+extern _X_EXPORT Bool serverRunning;
+extern _X_EXPORT pthread_mutex_t serverRunningMutex;
+extern _X_EXPORT pthread_cond_t serverRunningCond;
+
 #endif                          /* INPUT_H */
diff --git a/include/inputthread.h b/include/inputthread.h
new file mode 100644
index 0000000..aab8cb9
--- /dev/null
+++ b/include/inputthread.h
@@ -0,0 +1,45 @@
+/* inputthread.h -- Threaded generation of input events.
+ *
+ * Copyright © 2007-2008 Tiago Vignatti <vignatti at freedesktop org>
+ * Copyright © 2010 Nokia
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: Fernando Carrijo <fcarrijo at freedesktop org>
+ *          Tiago Vignatti <vignatti at freedesktop org>
+ */
+
+#ifndef _INPUTTHREAD_H_
+#define _INPUTTHREAD_H_
+
+#include "os.h"
+
+extern void InputThreadPreInit(void);
+extern void InputThreadInit(void);
+extern void InputThreadFini(void);
+
+extern int InputThreadRegisterDev(int fd,
+                                  NotifyFdProcPtr readInputProc,
+                                  void *readInputArgs);
+
+extern int InputThreadUnregisterDev(int fd);
+
+extern _X_EXPORT Bool InputThreadEnable;
+
+#endif /* _INPUTTHREAD_H_ */
diff --git a/include/misc.h b/include/misc.h
index 56e138c..006f768 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -79,6 +79,7 @@ OF THIS SOFTWARE.
 
 #include <stddef.h>
 #include <stdint.h>
+#include <pthread.h>
 
 #ifndef MAXSCREENS
 #define MAXSCREENS	16
diff --git a/mi/mieq.c b/mi/mieq.c
index 8fbe6c3..ff6261b 100644
--- a/mi/mieq.c
+++ b/mi/mieq.c
@@ -87,14 +87,6 @@ typedef struct _EventQueue {
 
 static EventQueueRec miEventQueue;
 
-#ifdef XQUARTZ
-#include  <pthread.h>
-static pthread_mutex_t miEventQueueMutex = PTHREAD_MUTEX_INITIALIZER;
-
-extern BOOL serverRunning;
-extern pthread_mutex_t serverRunningMutex;
-extern pthread_cond_t serverRunningCond;
-
 static inline void
 wait_for_server_init(void)
 {
@@ -106,7 +98,6 @@ wait_for_server_init(void)
         pthread_mutex_unlock(&serverRunningMutex);
     }
 }
-#endif
 
 static size_t
 mieqNumEnqueued(EventQueuePtr eventQueue)
@@ -250,10 +241,7 @@ mieqEnqueue(DeviceIntPtr pDev, InternalEvent *e)
     Time time;
     size_t n_enqueued;
 
-#ifdef XQUARTZ
     wait_for_server_init();
-    pthread_mutex_lock(&miEventQueueMutex);
-#endif
 
     verify_internal_event(e);
 
@@ -296,9 +284,6 @@ mieqEnqueue(DeviceIntPtr pDev, InternalEvent *e)
             xorg_backtrace();
         }
 
-#ifdef XQUARTZ
-        pthread_mutex_unlock(&miEventQueueMutex);
-#endif
         return;
     }
 
@@ -319,9 +304,6 @@ mieqEnqueue(DeviceIntPtr pDev, InternalEvent *e)
 
     miEventQueue.lastMotion = isMotion;
     miEventQueue.tail = (oldtail + 1) % miEventQueue.nevents;
-#ifdef XQUARTZ
-    pthread_mutex_unlock(&miEventQueueMutex);
-#endif
 }
 
 /**
@@ -342,31 +324,19 @@ mieqEnqueue(DeviceIntPtr pDev, InternalEvent *e)
 void
 mieqSwitchScreen(DeviceIntPtr pDev, ScreenPtr pScreen, Bool set_dequeue_screen)
 {
-#ifdef XQUARTZ
-    pthread_mutex_lock(&miEventQueueMutex);
-#endif
     EnqueueScreen(pDev) = pScreen;
     if (set_dequeue_screen)
         DequeueScreen(pDev) = pScreen;
-#ifdef XQUARTZ
-    pthread_mutex_unlock(&miEventQueueMutex);
-#endif
 }
 
 void
 mieqSetHandler(int event, mieqHandler handler)
 {
-#ifdef XQUARTZ
-    pthread_mutex_lock(&miEventQueueMutex);
-#endif
     if (handler && miEventQueue.handlers[event])
         ErrorF("[mi] mieq: warning: overriding existing handler %p with %p for "
                "event %d\n", miEventQueue.handlers[event], handler, event);
 
     miEventQueue.handlers[event] = handler;
-#ifdef XQUARTZ
-    pthread_mutex_unlock(&miEventQueueMutex);
-#endif
 }
 
 /**
@@ -581,9 +551,7 @@ mieqProcessInputEvents(void)
     size_t n_enqueued;
     static Bool inProcessInputEvents = FALSE;
 
-#ifdef XQUARTZ
-    pthread_mutex_lock(&miEventQueueMutex);
-#endif
+    input_lock();
 
     /*
      * report an error if mieqProcessInputEvents() is called recursively;
@@ -621,9 +589,7 @@ mieqProcessInputEvents(void)
 
         miEventQueue.head = (miEventQueue.head + 1) % miEventQueue.nevents;
 
-#ifdef XQUARTZ
-        pthread_mutex_unlock(&miEventQueueMutex);
-#endif
+        input_unlock();
 
         master = (dev) ? GetMaster(dev, MASTER_ATTACHED) : NULL;
 
@@ -647,14 +613,10 @@ mieqProcessInputEvents(void)
               event.device_event.flags & TOUCH_POINTER_EMULATED)))
             miPointerUpdateSprite(dev);
 
-#ifdef XQUARTZ
-        pthread_mutex_lock(&miEventQueueMutex);
-#endif
+        input_lock();
     }
 
     inProcessInputEvents = FALSE;
 
-#ifdef XQUARTZ
-    pthread_mutex_unlock(&miEventQueueMutex);
-#endif
+    input_unlock();
 }
diff --git a/os/Makefile.am b/os/Makefile.am
index a1bbb4d..fc49a73 100644
--- a/os/Makefile.am
+++ b/os/Makefile.am
@@ -14,6 +14,7 @@ libos_la_SOURCES = 	\
 	backtrace.c	\
 	client.c	\
 	connection.c	\
+	inputthread.c	\
 	io.c		\
 	mitauth.c	\
 	oscolor.c	\
diff --git a/os/inputthread.c b/os/inputthread.c
new file mode 100644
index 0000000..f0535d0
--- /dev/null
+++ b/os/inputthread.c
@@ -0,0 +1,381 @@
+/* inputthread.c -- Threaded generation of input events.
+ *
+ * Copyright © 2007-2008 Tiago Vignatti <vignatti at freedesktop org>
+ * Copyright © 2010 Nokia
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: Fernando Carrijo <fcarrijo at freedesktop org>
+ *          Tiago Vignatti <vignatti at freedesktop org>
+ */
+
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include <X11/Xpoll.h>
+#include "inputthread.h"
+#include "inputstr.h"
+#include "opaque.h"
+#include "osdep.h"
+
+Bool InputThreadEnable = TRUE;
+
+/**
+ * An input device as seen by the threaded input facility
+ */
+typedef struct _InputThreadDevice {
+    struct xorg_list list;
+    NotifyFdProcPtr readInputProc;
+    void *readInputArgs;
+    int fd;
+} InputThreadDevice;
+
+/**
+ * The threaded input facility.
+ *
+ * For now, we have one instance for all input devices.
+ */
+typedef struct {
+    pthread_t thread;
+    struct xorg_list devs;
+    fd_set fds;
+    int readPipe;
+    int writePipe;
+} InputThreadInfo;
+
+static InputThreadInfo *inputThreadInfo;
+
+static int hotplugPipeRead = -1;
+static int hotplugPipeWrite = -1;
+
+/**
+ * Notify a thread about the availability of new asynchronously enqueued input
+ * events.
+ *
+ * @see WaitForSomething()
+ */
+static void
+InputThreadFillPipe(int writeHead)
+{
+    int ret;
+    char byte = 0;
+    fd_set writePipe;
+
+    FD_ZERO(&writePipe);
+
+    while (1) {
+        ret = write(writeHead, &byte, 1);
+        if (!ret)
+            FatalError("input-thread: write() returned 0");
+        if (ret > 0) {
+            break;
+        }
+        if (errno != EAGAIN)
+            FatalError("input-thread: filling pipe");
+
+        DebugF("input-thread: pipe full\n");
+        FD_SET(writeHead, &writePipe);
+        Select(writeHead + 1, NULL, &writePipe, NULL, NULL);
+    }
+}
+
+/**
+ * Consume eventual notifications left by a thread.
+ *
+ * @see WaitForSomething()
+ * @see InputThreadFillPipe()
+ */
+static int
+InputThreadReadPipe(int readHead)
+{
+    int ret, array[10];
+
+    ret = read(readHead, &array, sizeof(array));
+    if (ret >= 0)
+        return ret;
+
+    if (errno != EAGAIN)
+        FatalError("input-thread: draining pipe (%d)", errno);
+
+    return 1;
+}
+
+/**
+ * Register an input device in the threaded input facility
+ *
+ * @param fd File descriptor which identifies the input device
+ * @param readInputProc Procedure used to read input from the device
+ * @param readInputArgs Arguments to be consumed by the above procedure
+ *
+ * return 1 if success; 0 otherwise.
+ */
+int
+InputThreadRegisterDev(int fd,
+                       NotifyFdProcPtr readInputProc,
+                       void *readInputArgs)
+{
+    InputThreadDevice *new;
+
+    if (!inputThreadInfo)
+        return SetNotifyFd(fd, readInputProc, X_NOTIFY_READ, readInputArgs);
+
+    new = calloc(1, sizeof(InputThreadDevice));
+    if (new == NULL) {
+        DebugF("input-thread: could not register device\n");
+        return 0;
+    }
+
+    new->fd = fd;
+    new->readInputProc = readInputProc;
+    new->readInputArgs = readInputArgs;
+
+    xorg_list_add(&new->list, &inputThreadInfo->devs);
+
+    FD_SET(fd, &inputThreadInfo->fds);
+
+    InputThreadFillPipe(hotplugPipeWrite);
+    DebugF("input-thread: registered device %d\n", fd);
+
+    return 1;
+}
+
+/**
+ * Unregister a device in the threaded input facility
+ *
+ * @param fd File descriptor which identifies the input device
+ *
+ * @return 1 if success; 0 otherwise.
+ */
+int
+InputThreadUnregisterDev(int fd)
+{
+    InputThreadDevice *dev;
+
+    /* return silently if input thread is already finished (e.g., at
+     * DisableDevice time, evdev tries to call this function again through
+     * xf86RemoveEnabledDevice */
+    if (!inputThreadInfo) {
+        RemoveNotifyFd(fd);
+        return 0;
+    }
+
+    xorg_list_for_each_entry(dev, &inputThreadInfo->devs, list)
+        if (dev->fd == fd)
+            break;
+
+    /* fd didn't match any registered device. */
+    if (&dev->list == &inputThreadInfo->devs)
+        return 0;
+
+    xorg_list_del(&dev->list);
+
+    FD_CLR(fd, &inputThreadInfo->fds);
+    free(dev);
+
+    InputThreadFillPipe(hotplugPipeWrite);
+    DebugF("input-thread: unregistered device: %d\n", fd);
+
+    return 1;
+}
+
+/**
+ * The workhorse of threaded input event generation.
+ *
+ * Or if you prefer: The WaitForSomething for input devices. :)
+ *
+ * Runs in parallel with the server main thread, listening to input devices in
+ * an endless loop. Whenever new input data is made available, calls the
+ * proper device driver's routines which are ultimately responsible for the
+ * generation of input events.
+ *
+ * @see InputThreadPreInit()
+ * @see InputThreadInit()
+ */
+
+static void*
+InputThreadDoWork(void *arg)
+{
+    fd_set readyFds;
+    InputThreadDevice *dev, *next;
+
+    FD_ZERO(&readyFds);
+
+    while (1)
+    {
+        XFD_COPYSET(&inputThreadInfo->fds, &readyFds);
+        FD_SET(hotplugPipeRead, &readyFds);
+
+        DebugF("input-thread: InputThreadDoWork waiting for devices\n");
+
+        if (Select(MAXSELECT, &readyFds, NULL, NULL, NULL) < 0) {
+            if (errno == EINVAL)
+                FatalError("input-thread: InputThreadDoWork (%s)", strerror(errno));
+            else if (errno != EINTR)
+                ErrorF("input-thread: InputThreadDoWork (%s)\n", strerror(errno));
+        }
+
+        DebugF("input-thread: InputThreadDoWork generating events\n");
+
+        /* Call the device drivers to generate input events for us */
+        xorg_list_for_each_entry_safe(dev, next, &inputThreadInfo->devs, list)
+            if (FD_ISSET(dev->fd, &readyFds) && dev->readInputProc) {
+                input_lock();
+                dev->readInputProc(dev->fd, X_NOTIFY_READ, dev->readInputArgs);
+                input_unlock();
+            }
+
+        /* Kick main thread to process the generated input events and drain
+         * events from hotplug pipe */
+        InputThreadFillPipe(inputThreadInfo->writePipe);
+        InputThreadReadPipe(hotplugPipeRead);
+    }
+}
+
+static void
+InputThreadWakeup(void *blockData, int err, void *pReadmask)
+{
+    InputThreadReadPipe(inputThreadInfo->readPipe);
+}
+
+/**
+ * Pre-initialize the facility used for threaded generation of input events
+ *
+ */
+void
+InputThreadPreInit(void)
+{
+    int fds[2], hotplugPipe[2];
+
+    if (!InputThreadEnable)
+        return;
+
+    if (pipe(fds) < 0)
+        FatalError("input-thread: could not create pipe");
+
+     if (pipe(hotplugPipe) < 0)
+        FatalError("input-thread: could not create pipe");
+
+    inputThreadInfo = malloc(sizeof(InputThreadInfo));
+    if (!inputThreadInfo)
+        FatalError("input-thread: could not allocate memory");
+
+    inputThreadInfo->thread = 0;
+    xorg_list_init(&inputThreadInfo->devs);
+    FD_ZERO(&inputThreadInfo->fds);
+
+    /* By making read head non-blocking, we ensure that while the main thread
+     * is busy servicing client requests, the dedicated input thread can work
+     * in parallel.
+     */
+    inputThreadInfo->readPipe = fds[0];
+    fcntl(inputThreadInfo->readPipe, F_SETFL, O_NONBLOCK | O_CLOEXEC);
+    AddGeneralSocket(inputThreadInfo->readPipe);
+    RegisterBlockAndWakeupHandlers((BlockHandlerProcPtr)NoopDDA,
+                                   InputThreadWakeup, NULL);
+
+    inputThreadInfo->writePipe = fds[1];
+
+    hotplugPipeRead = hotplugPipe[0];
+    fcntl(hotplugPipeRead, F_SETFL, O_NONBLOCK | O_CLOEXEC);
+    hotplugPipeWrite = hotplugPipe[1];
+}
+
+/**
+ * Start the threaded generation of input events. This routine complements what
+ * was previously done by InputThreadPreInit(), being only responsible for
+ * creating the dedicated input thread.
+ *
+ */
+void
+InputThreadInit(void)
+{
+    pthread_attr_t attr;
+
+    /* If the driver hasn't asked for input thread support by calling
+     * InputThreadPreInit, then do nothing here
+     */
+    if (!inputThreadInfo)
+        return;
+
+    pthread_attr_init(&attr);
+
+    /* For OSes that differentiate between processes and threads, the following
+     * lines have sense. Linux uses the 1:1 thread model. The scheduler handles
+     * every thread as a normal process. Therefore this probably has no meaning
+     * if we are under Linux.
+     */
+    if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM) != 0)
+        ErrorF("input-thread: error setting thread scope\n");
+
+    if (pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN) != 0)
+        ErrorF("input-thread: error setting thread stack size\n");
+
+    DebugF("input-thread: creating thread\n");
+    pthread_create(&inputThreadInfo->thread, &attr,
+                   &InputThreadDoWork, NULL);
+
+    pthread_attr_destroy (&attr);
+}
+
+/**
+ * Stop the threaded generation of input events
+ *
+ * This function is supposed to be called at server shutdown time only.
+ */
+void
+InputThreadFini(void)
+{
+    InputThreadDevice *dev, *next;
+
+    if (!inputThreadInfo)
+        return;
+
+    pthread_cancel(inputThreadInfo->thread);
+    pthread_join(inputThreadInfo->thread, NULL);
+
+    xorg_list_for_each_entry_safe(dev, next, &inputThreadInfo->devs, list) {
+        FD_CLR(dev->fd, &inputThreadInfo->fds);
+        free(dev);
+    }
+    xorg_list_init(&inputThreadInfo->devs);
+    FD_ZERO(&inputThreadInfo->fds);
+
+    RemoveGeneralSocket(inputThreadInfo->readPipe);
+    RemoveBlockAndWakeupHandlers((BlockHandlerProcPtr)NoopDDA,
+                                 InputThreadWakeup, NULL);
+    close(inputThreadInfo->readPipe);
+    close(inputThreadInfo->writePipe);
+    inputThreadInfo->readPipe = -1;
+    inputThreadInfo->writePipe = -1;
+
+    close(hotplugPipeRead);
+    close(hotplugPipeWrite);
+    hotplugPipeRead = -1;
+    hotplugPipeWrite = -1;
+
+    free(inputThreadInfo);
+    inputThreadInfo = NULL;
+}
diff --git a/os/utils.c b/os/utils.c
index 903fbc9..1fbcce8 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -586,7 +586,7 @@ UseMsg(void)
     ErrorF("-xinerama              Disable XINERAMA extension\n");
 #endif
     ErrorF
-        ("-dumbSched             Disable smart scheduling, enable old behavior\n");
+        ("-dumbSched             Disable smart scheduling and threaded input, enable old behavior\n");
     ErrorF("-schedInterval int     Set scheduler interval in msec\n");
     ErrorF("-sigstop               Enable SIGSTOP based startup\n");
     ErrorF("+extension name        Enable extension\n");
@@ -1004,11 +1004,12 @@ ProcessCommandLine(int argc, char *argv[])
             i = skip - 1;
         }
 #endif
-#if HAVE_SETITIMER
         else if (strcmp(argv[i], "-dumbSched") == 0) {
+            InputThreadEnable = FALSE;
+#if HAVE_SETITIMER
             SmartScheduleSignalEnable = FALSE;
-        }
 #endif
+        }
         else if (strcmp(argv[i], "-schedInterval") == 0) {
             if (++i < argc) {
                 SmartScheduleInterval = atoi(argv[i]);
-- 
2.6.2



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