[PATCH/RFC] xfree86: add a hook to replace the new console handler.

[Tiago Vignatti]

On Mon, Sep 06, 2010 at 03:56:31AM +0200, ext Peter Hutterer wrote:
> This hook is only necessary for the keyboard driver to remove the race
> condition between drain_console() and the driver's ReadInput (Bug 29969).
> 
> The idea is that a driver that needs to handle events from the console
> calls xf86ReplaceConsoleHandler() with it's own ReadInput (or NULL) and thus
> removes the drain_console call. It's the driver's responsibility to restore
> the previous behaviour when the driver is unloaded.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> CC: Thomas Hellstrom <thellstrom at vmware.com>
> ---
> compile-tested only but something like this may fix the issue, given the
> matching code in the keyboard driver?
> 
> since we haven't bumped the API yet for 1.10 and I've got a lot of changes
> anyway, queing this one up for input abi 12 would be easy.
> 
>  hw/xfree86/common/xf86.h               |    1 +
>  hw/xfree86/common/xf86Events.c         |   19 +++++++++++++++++++
>  hw/xfree86/os-support/linux/lnx_init.c |    4 +---
>  3 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/xfree86/common/xf86.h b/hw/xfree86/common/xf86.h
> index 886c25b..ad271f1 100644
> --- a/hw/xfree86/common/xf86.h
> +++ b/hw/xfree86/common/xf86.h
> @@ -208,6 +208,7 @@ extern _X_EXPORT void xf86InterceptSigIll(void (*sigillhandler)(void));
>  extern _X_EXPORT Bool xf86EnableVTSwitch(Bool new);
>  extern _X_EXPORT void xf86ProcessActionEvent(ActionEvent action, void *arg);
>  extern _X_EXPORT void xf86PrintBacktrace(void);
> +extern _X_EXPORT InputHandlerProc xf86SetConsoleHandler(InputHandlerProc handler, pointer data);

xf86Xinput.h isn't more appropriated? 

  
>  /* xf86Helper.c */
>  
> diff --git a/hw/xfree86/common/xf86Events.c b/hw/xfree86/common/xf86Events.c
> index 2e82848..8b6cd2b 100644
> --- a/hw/xfree86/common/xf86Events.c
> +++ b/hw/xfree86/common/xf86Events.c
> @@ -600,6 +600,25 @@ xf86AddGeneralHandler(int fd, InputHandlerProc proc, pointer data)
>      return ih;
>  }
>  
> +/**
> + * Set the handler for the console's fd. Replaces (and returns) the previous
> + * handler or NULL, whichever appropriate.
> + */
> +InputHandlerProc
> +xf86SetConsoleHandler(InputHandlerProc proc, pointer data)
> +{
> +    static InputHandlerProc handler = NULL;
> +    InputHandlerProc old_handler = handler;
> +
> +    if (old_handler)
> +        xf86RemoveGeneralHandler(old_handler);
> +
> +    xf86AddGeneralHandler(xf86Info.consoleFd, proc, data);
> +    handler = proc;
> +
> +    return old_handler;
> +}
> +
>  static void
>  removeInputHandler(IHPtr ih)
>  {
> diff --git a/hw/xfree86/os-support/linux/lnx_init.c b/hw/xfree86/os-support/linux/lnx_init.c
> index 92bfde4..bf61ceb 100644
> --- a/hw/xfree86/os-support/linux/lnx_init.c
> +++ b/hw/xfree86/os-support/linux/lnx_init.c
> @@ -277,9 +277,7 @@ xf86OpenConsole(void)
>              tcsetattr(xf86Info.consoleFd, TCSANOW, &nTty);
>  
>              /* need to keep the buffer clean, else the kernel gets angry */
> -	    if (xf86Info.allowEmptyInput)
> -		console_handler = xf86AddGeneralHandler(xf86Info.consoleFd,
> -							drain_console, NULL);
> +	    xf86SetConsoleHandler(drain_console, NULL);
>  
>  	    /* we really should have a InitOSInputDevices() function instead
>  	     * of Init?$#*&Device(). So I just place it here */
> -- 

For the patch: 
Reviewed-by: Tiago Vignatti <tiago.vignatti at nokia.com>

BTW, this one also mess Fernando's patchset: 

http://lists.x.org/archives/xorg-devel/2010-August/012470.html

             Tiago