Attachment 126759 Details for Bug 97880 – proposed patch v4

[patch] proposed patch v4

0001-input-fix-VT-switch-disabling-devices.patch (text/plain), 5.36 KB, created by Mihail Konev on 2016-09-24 10:18:20 UTC

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Creator: Mihail Konev

Created: 2016-09-24 10:18:20 UTC

Size: 5.36 KB

patch

obsolete

>From 4b8473e003a72c7093913d8f87d7337a1e3d727e Mon Sep 17 00:00:00 2001
>From: Mihail Konev <k.mvc@ya.ru>
>Date: Fri, 23 Sep 2016 15:04:26 +0000
>Subject: [PATCH xserver] input: fix VT switch disabling devices
>
>Make sure device removes are processed before doing a VT switch,
>so that no removes are "overwritten" with attachments afterwards
>(before the main thread releases the input lock, letting them be
>processed), which would leave affected devices disabled.
>
>Pass a timeout to input poll instead of telling it to wait forever,
>so that no deadlock before VT switch is possible if main thread
>waits for release processing only by the time input thread
>is already done and does another poll.
>
>When preparing a VT switch, temprorarily decrease polling
>timeout, so there is (likely) no noticeable stall.
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97880
>Regressed-in: 52d6a1e832a5e62289dd4f32824ae16a78dfd7e8
>Signed-off-by: Mihail Konev <k.mvc@ya.ru>
>---
>
>The patch could be wrong in regard to namings (InputThreadWait vs. input_wait)
>and multiple input threads (struct InputThreadInfo).
>
> hw/xfree86/common/xf86Events.c |  4 ++++
> include/input.h                |  4 ++++
> os/inputthread.c               | 39 ++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 46 insertions(+), 1 deletion(-)
>
>diff --git a/hw/xfree86/common/xf86Events.c b/hw/xfree86/common/xf86Events.c
>index 9a8f432a0556..8290c117116e 100644
>--- a/hw/xfree86/common/xf86Events.c
>+++ b/hw/xfree86/common/xf86Events.c
>@@ -430,6 +430,7 @@ xf86VTLeave(void)
>      * Keep the order: Disable Device > LeaveVT
>      *                        EnterVT > EnableDevice
>      */
>+    InputThreadPollTimeoutSmall();
>     for (ih = InputHandlers; ih; ih = ih->next) {
>         if (ih->is_input)
>             xf86DisableInputHandler(ih);
>@@ -439,6 +440,9 @@ xf86VTLeave(void)
>     for (pInfo = xf86InputDevs; pInfo; pInfo = pInfo->next)
>         xf86DisableInputDeviceForVTSwitch(pInfo);
> 
>+    InputThreadWaitForProcessingAllRemoves();
>+    InputThreadPollTimeoutNormal();
>+
>     input_lock();
>     for (i = 0; i < xf86NumScreens; i++)
>         xf86Screens[i]->LeaveVT(xf86Screens[i]);
>diff --git a/include/input.h b/include/input.h
>index e0f6b9b01d97..1afb3f89a33a 100644
>--- a/include/input.h
>+++ b/include/input.h
>@@ -719,6 +719,10 @@ extern _X_EXPORT void input_lock(void);
> extern _X_EXPORT void input_unlock(void);
> extern _X_EXPORT void input_force_unlock(void);
> 
>+extern _X_EXPORT void InputThreadPollTimeoutSmall(void);
>+extern _X_EXPORT void InputThreadPollTimeoutNormal(void);
>+extern _X_EXPORT void InputThreadWaitForProcessingAllRemoves(void);
>+
> extern void InputThreadPreInit(void);
> extern void InputThreadInit(void);
> extern void InputThreadFini(void);
>diff --git a/os/inputthread.c b/os/inputthread.c
>index 6aa0a9ce6fb5..fab3c30954e5 100644
>--- a/os/inputthread.c
>+++ b/os/inputthread.c
>@@ -90,6 +90,12 @@ static pthread_mutex_t input_mutex;
> static Bool input_mutex_initialized;
> #endif
> 
>+int input_poll_timeout_ms;
>+
>+static Bool waiting_for_processing_all_removes = FALSE;
>+static int unprocessed_removes_count = 0;
>+static pthread_barrier_t all_removes_processed_barrier;
>+
> void
> input_lock(void)
> {
>@@ -125,6 +131,25 @@ input_force_unlock(void)
>     }
> }
> 
>+void
>+InputThreadPollTimeoutSmall(void)
>+{
>+    input_poll_timeout_ms = 4;
>+}
>+
>+void
>+InputThreadPollTimeoutNormal(void)
>+{
>+    input_poll_timeout_ms = 200;
>+}
>+
>+void
>+InputThreadWaitForProcessingAllRemoves(void)
>+{
>+    waiting_for_processing_all_removes = TRUE;
>+    pthread_barrier_wait(&all_removes_processed_barrier);
>+}
>+
> /**
>  * Notify a thread about the availability of new asynchronously enqueued input
>  * events.
>@@ -267,6 +292,7 @@ InputThreadUnregisterDev(int fd)
> 
>     dev->state = device_state_removed;
>     inputThreadInfo->changed = TRUE;
>+    unprocessed_removes_count++;
> 
>     input_unlock();
> 
>@@ -348,13 +374,19 @@ InputThreadDoWork(void *arg)
>                     ospoll_remove(inputThreadInfo->fds, dev->fd);
>                     xorg_list_del(&dev->node);
>                     free(dev);
>+                    unprocessed_removes_count--;
>                     break;
>                 }
>             }
>             input_unlock();
>         }
> 
>-        if (ospoll_wait(inputThreadInfo->fds, -1) < 0) {
>+        if (waiting_for_processing_all_removes && !unprocessed_removes_count) {
>+            waiting_for_processing_all_removes = FALSE;
>+            pthread_barrier_wait(&all_removes_processed_barrier);
>+        }
>+
>+        if (ospoll_wait(inputThreadInfo->fds, input_poll_timeout_ms) < 0) {
>             if (errno == EINVAL)
>                 FatalError("input-thread: %s (%s)", __func__, strerror(errno));
>             else if (errno != EINTR)
>@@ -400,6 +432,8 @@ InputThreadPreInit(void)
>     if (!inputThreadInfo)
>         FatalError("input-thread: could not allocate memory");
> 
>+    pthread_barrier_init(&all_removes_processed_barrier, NULL, 2);
>+
>     inputThreadInfo->thread = 0;
>     xorg_list_init(&inputThreadInfo->devs);
>     inputThreadInfo->fds = ospoll_create();
>@@ -434,6 +468,7 @@ InputThreadPreInit(void)
>     pthread_setname_np ("MainThread");
> #endif
> 
>+    InputThreadPollTimeoutNormal();
> }
> 
> /**
>@@ -517,6 +552,8 @@ int xthread_sigmask(int how, const sigset_t *set, sigset_t *oldset)
> 
> Bool InputThreadEnable = FALSE;
> 
>+void input_wait_for_processing_all_removes(void) {};
>+
> void input_lock(void) {}
> void input_unlock(void) {}
> void input_force_unlock(void) {}
>-- 
>2.9.2
>

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