[PATCH] Fix drain_console unregistration

[Tomáš Trnka]

Bug introduced by 9dca441670d261a9a9fb6108960ed48f3d58fb7f
xfree86: add a hook to replace the new console handler.

console_handler was not being set, making the server eat up CPU spinning
in WaitForSomething selecting consoleFd over and over again, every time
trying to unregister drain_console without success due to
console_handler being NULL.

Let's just fix the unregistration in xf86SetConsoleHandler() and use that.

But wait, there could be a catch: If some driver replaced the handler using
xf86SetConsoleHandler(), the unregistration in xf86CloseConsole will unregister
that one. I don't understand Xorg well enough to know whether this poses a
problem (could mess up driver deinit somehow or something like that). As it is,
xf86SetConsoleHandler() doesn't offer any way to prevent this (i.e. check which
handler is currently registered).

I had been using it for two days on my machine that previously hit 100% CPU
several times a day. That has now gone away without any new problems appearing.

Signed-off-by: Tomas Trnka <tomastrnka at gmx.com>
---
 hw/xfree86/common/xf86Events.c         |    9 ++++-----
 hw/xfree86/os-support/linux/lnx_init.c |   14 ++++++--------
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/hw/xfree86/common/xf86Events.c b/hw/xfree86/common/xf86Events.c
index 84c0d18..8511ea1 100644
--- a/hw/xfree86/common/xf86Events.c
+++ b/hw/xfree86/common/xf86Events.c
@@ -603,16 +603,15 @@ xf86AddGeneralHandler(int fd, InputHandlerProc proc, pointer data)
 InputHandlerProc
 xf86SetConsoleHandler(InputHandlerProc proc, pointer data)
 {
-    static InputHandlerProc handler = NULL;
-    InputHandlerProc old_handler = handler;
+    static IHPtr handler = NULL;
+    IHPtr old_handler = handler;
 
     if (old_handler)
         xf86RemoveGeneralHandler(old_handler);
 
-    xf86AddGeneralHandler(xf86Info.consoleFd, proc, data);
-    handler = proc;
+    handler = xf86AddGeneralHandler(xf86Info.consoleFd, proc, data);
 
-    return old_handler;
+    return (old_handler) ? old_handler->ihproc : NULL;
 }
 
 static void
diff --git a/hw/xfree86/os-support/linux/lnx_init.c b/hw/xfree86/os-support/linux/lnx_init.c
index 77dfb2f..adcc467 100644
--- a/hw/xfree86/os-support/linux/lnx_init.c
+++ b/hw/xfree86/os-support/linux/lnx_init.c
@@ -47,15 +47,12 @@ static char vtname[11];
 static struct termios tty_attr; /* tty state to restore */
 static int tty_mode; /* kbd mode to restore */
 
-static void *console_handler;
-
 static void
 drain_console(int fd, void *closure)
 {
     errno = 0;
     if (tcflush(fd, TCIOFLUSH) == -1 && errno == EIO) {
-	xf86RemoveGeneralHandler(console_handler);
-	console_handler = NULL;
+        xf86SetConsoleHandler(NULL, NULL);
     }
 }
 
@@ -259,10 +256,11 @@ xf86CloseConsole(void)
         return;
     }
 
-    if (console_handler) {
-	xf86RemoveGeneralHandler(console_handler);
-	console_handler = NULL;
-    };
+    /*
+     * unregister the drain_console handler
+     * - what to do if someone else changed it in the meantime?
+     */
+    xf86SetConsoleHandler(NULL, NULL);
 
     /* Back to text mode ... */
     SYSCALL(ret = ioctl(xf86Info.consoleFd, KDSETMODE, KD_TEXT));
-- 
1.7.6.4