1. Patchew
  2. Xen
  3. View series

[PATCH] Input: xen-kbdfront - drop keys to shrink modalias

Jason Andryuk posted 1 patch 1 year, 6 months ago
Failed in applying to current master (apply log)
There is a newer version of this series
drivers/input/misc/xen-kbdfront.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
[PATCH] Input: xen-kbdfront - drop keys to shrink modalias
Posted by Jason Andryuk 1 year, 6 months ago 
xen kbdfront registers itself as being able to deliver *any* key since
it doesn't know what keys the backend may produce.

Unfortunately, the generated modalias gets too large and uevent creation
fails with -ENOMEM.

This can lead to gdm not using the keyboard since there is no seat
associated [1] and the debian installer crashing [2].

Trim the ranges of key capabilities by removing some BTN_* ranges.
While doing this, some neighboring undefined ranges are removed to trim
it further.

This removes:
BTN_DPAD_UP(0x220)..BTN_DPAD_RIGHT(0x223)
Empty space 0x224..0x229

Emtpy space 0x2bd..0x2bf
BTN_TRIGGER_HAPPY(0x2c0)..BTN_TRIGGER_HAPPY40(0x2e7)
Empty space 0x2e8..0x2ff

The modalias shrinks from 2082 to 1754 bytes.

[1] https://github.com/systemd/systemd/issues/22944
[2] https://lore.kernel.org/xen-devel/87o8dw52jc.fsf@vps.thesusis.net/T/

Cc: Phillip Susi <phill@thesusis.net>
Cc: stable@vger.kernel.org
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
---
 drivers/input/misc/xen-kbdfront.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index 8d8ebdc2039b..23f37211be78 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -256,7 +256,14 @@ static int xenkbd_probe(struct xenbus_device *dev,
 		__set_bit(EV_KEY, kbd->evbit);
 		for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
 			__set_bit(i, kbd->keybit);
-		for (i = KEY_OK; i < KEY_MAX; i++)
+		/* In theory we want to go KEY_OK..KEY_MAX, but that grows the
+		 * modalias line too long.  KEY_KBD_LCD_MENU5 is the last
+		 * defined non-button key. There is a gap of buttons from
+		 * BTN_DPAD_UP..BTN_DPAD_RIGHT and KEY_ALS_TOGGLE is the next
+		 * defined. */
+		for (i = KEY_OK; i < BTN_DPAD_UP; i++)
+			__set_bit(i, kbd->keybit);
+		for (i = KEY_ALS_TOGGLE; i <= KEY_KBD_LCD_MENU5; i++)
 			__set_bit(i, kbd->keybit);
 
 		ret = input_register_device(kbd);
-- 
2.37.3
Re: [PATCH] Input: xen-kbdfront - drop keys to shrink modalias
Posted by Mattijs Korpershoek 1 year, 6 months ago 
On Wed, Oct 19, 2022 at 16:14, Jason Andryuk <jandryuk@gmail.com> wrote:

> xen kbdfront registers itself as being able to deliver *any* key since
> it doesn't know what keys the backend may produce.
>
> Unfortunately, the generated modalias gets too large and uevent creation
> fails with -ENOMEM.
>
> This can lead to gdm not using the keyboard since there is no seat
> associated [1] and the debian installer crashing [2].
>
> Trim the ranges of key capabilities by removing some BTN_* ranges.
> While doing this, some neighboring undefined ranges are removed to trim
> it further.
>
> This removes:
> BTN_DPAD_UP(0x220)..BTN_DPAD_RIGHT(0x223)
> Empty space 0x224..0x229
>
> Emtpy space 0x2bd..0x2bf
> BTN_TRIGGER_HAPPY(0x2c0)..BTN_TRIGGER_HAPPY40(0x2e7)
> Empty space 0x2e8..0x2ff
>
> The modalias shrinks from 2082 to 1754 bytes.
>
> [1] https://github.com/systemd/systemd/issues/22944
> [2] https://lore.kernel.org/xen-devel/87o8dw52jc.fsf@vps.thesusis.net/T/
>
> Cc: Phillip Susi <phill@thesusis.net>
> Cc: stable@vger.kernel.org
> Signed-off-by: Jason Andryuk <jandryuk@gmail.com>

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

> ---
>  drivers/input/misc/xen-kbdfront.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
> index 8d8ebdc2039b..23f37211be78 100644
> --- a/drivers/input/misc/xen-kbdfront.c
> +++ b/drivers/input/misc/xen-kbdfront.c
> @@ -256,7 +256,14 @@ static int xenkbd_probe(struct xenbus_device *dev,
>  		__set_bit(EV_KEY, kbd->evbit);
>  		for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
>  			__set_bit(i, kbd->keybit);
> -		for (i = KEY_OK; i < KEY_MAX; i++)
> +		/* In theory we want to go KEY_OK..KEY_MAX, but that grows the
> +		 * modalias line too long.  KEY_KBD_LCD_MENU5 is the last
> +		 * defined non-button key. There is a gap of buttons from
> +		 * BTN_DPAD_UP..BTN_DPAD_RIGHT and KEY_ALS_TOGGLE is the next
> +		 * defined. */
> +		for (i = KEY_OK; i < BTN_DPAD_UP; i++)
> +			__set_bit(i, kbd->keybit);
> +		for (i = KEY_ALS_TOGGLE; i <= KEY_KBD_LCD_MENU5; i++)
>  			__set_bit(i, kbd->keybit);
>  
>  		ret = input_register_device(kbd);
> -- 
> 2.37.3
Re: [PATCH] Input: xen-kbdfront - drop keys to shrink modalias
Posted by Jason Andryuk 1 year, 6 months ago 
On Thu, Oct 20, 2022 at 4:31 AM Mattijs Korpershoek
<mkorpershoek@baylibre.com> wrote:
>
> On Wed, Oct 19, 2022 at 16:14, Jason Andryuk <jandryuk@gmail.com> wrote:
>
> > xen kbdfront registers itself as being able to deliver *any* key since
> > it doesn't know what keys the backend may produce.
> >
> > Unfortunately, the generated modalias gets too large and uevent creation
> > fails with -ENOMEM.
> >
> > This can lead to gdm not using the keyboard since there is no seat
> > associated [1] and the debian installer crashing [2].
> >
> > Trim the ranges of key capabilities by removing some BTN_* ranges.
> > While doing this, some neighboring undefined ranges are removed to trim
> > it further.
> >
> > This removes:
> > BTN_DPAD_UP(0x220)..BTN_DPAD_RIGHT(0x223)
> > Empty space 0x224..0x229
> >
> > Emtpy space 0x2bd..0x2bf
> > BTN_TRIGGER_HAPPY(0x2c0)..BTN_TRIGGER_HAPPY40(0x2e7)
> > Empty space 0x2e8..0x2ff
> >
> > The modalias shrinks from 2082 to 1754 bytes.
> >
> > [1] https://github.com/systemd/systemd/issues/22944
> > [2] https://lore.kernel.org/xen-devel/87o8dw52jc.fsf@vps.thesusis.net/T/
> >
> > Cc: Phillip Susi <phill@thesusis.net>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
>
> Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

This patch doesn't work and needs to be withdrawn.  My gdm/udev
workaround was still active when I tested, so that is why I had a
working keyboard.  Sorry about that.

Now the question is, which additional keys can be omitted to trim the
modalias to an acceptable size?

Regards,
Jason

> > ---
> >  drivers/input/misc/xen-kbdfront.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
> > index 8d8ebdc2039b..23f37211be78 100644
> > --- a/drivers/input/misc/xen-kbdfront.c
> > +++ b/drivers/input/misc/xen-kbdfront.c
> > @@ -256,7 +256,14 @@ static int xenkbd_probe(struct xenbus_device *dev,
> >               __set_bit(EV_KEY, kbd->evbit);
> >               for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
> >                       __set_bit(i, kbd->keybit);
> > -             for (i = KEY_OK; i < KEY_MAX; i++)
> > +             /* In theory we want to go KEY_OK..KEY_MAX, but that grows the
> > +              * modalias line too long.  KEY_KBD_LCD_MENU5 is the last
> > +              * defined non-button key. There is a gap of buttons from
> > +              * BTN_DPAD_UP..BTN_DPAD_RIGHT and KEY_ALS_TOGGLE is the next
> > +              * defined. */
> > +             for (i = KEY_OK; i < BTN_DPAD_UP; i++)
> > +                     __set_bit(i, kbd->keybit);
> > +             for (i = KEY_ALS_TOGGLE; i <= KEY_KBD_LCD_MENU5; i++)
> >                       __set_bit(i, kbd->keybit);
> >
> >               ret = input_register_device(kbd);
> > --
> > 2.37.3
Re: [PATCH] Input: xen-kbdfront - drop keys to shrink modalias
Posted by Jason Andryuk 1 year, 6 months ago 
On Thu, Oct 20, 2022 at 8:21 AM Jason Andryuk <jandryuk@gmail.com> wrote:
>
> On Thu, Oct 20, 2022 at 4:31 AM Mattijs Korpershoek
> <mkorpershoek@baylibre.com> wrote:
> >
> > On Wed, Oct 19, 2022 at 16:14, Jason Andryuk <jandryuk@gmail.com> wrote:
> >
> > > xen kbdfront registers itself as being able to deliver *any* key since
> > > it doesn't know what keys the backend may produce.
> > >
> > > Unfortunately, the generated modalias gets too large and uevent creation
> > > fails with -ENOMEM.
> > >
> > > This can lead to gdm not using the keyboard since there is no seat
> > > associated [1] and the debian installer crashing [2].
> > >
> > > Trim the ranges of key capabilities by removing some BTN_* ranges.
> > > While doing this, some neighboring undefined ranges are removed to trim
> > > it further.
> > >
> > > This removes:
> > > BTN_DPAD_UP(0x220)..BTN_DPAD_RIGHT(0x223)
> > > Empty space 0x224..0x229
> > >
> > > Emtpy space 0x2bd..0x2bf
> > > BTN_TRIGGER_HAPPY(0x2c0)..BTN_TRIGGER_HAPPY40(0x2e7)
> > > Empty space 0x2e8..0x2ff
> > >
> > > The modalias shrinks from 2082 to 1754 bytes.
> > >
> > > [1] https://github.com/systemd/systemd/issues/22944
> > > [2] https://lore.kernel.org/xen-devel/87o8dw52jc.fsf@vps.thesusis.net/T/
> > >
> > > Cc: Phillip Susi <phill@thesusis.net>
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
> >
> > Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
>
> This patch doesn't work and needs to be withdrawn.  My gdm/udev
> workaround was still active when I tested, so that is why I had a
> working keyboard.  Sorry about that.
>
> Now the question is, which additional keys can be omitted to trim the
> modalias to an acceptable size?
>
> Regards,
> Jason
>
> > > ---
> > >  drivers/input/misc/xen-kbdfront.c | 9 ++++++++-
> > >  1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
> > > index 8d8ebdc2039b..23f37211be78 100644
> > > --- a/drivers/input/misc/xen-kbdfront.c
> > > +++ b/drivers/input/misc/xen-kbdfront.c
> > > @@ -256,7 +256,14 @@ static int xenkbd_probe(struct xenbus_device *dev,
> > >               __set_bit(EV_KEY, kbd->evbit);
> > >               for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
> > >                       __set_bit(i, kbd->keybit);
> > > -             for (i = KEY_OK; i < KEY_MAX; i++)
> > > +             /* In theory we want to go KEY_OK..KEY_MAX, but that grows the
> > > +              * modalias line too long.  KEY_KBD_LCD_MENU5 is the last
> > > +              * defined non-button key. There is a gap of buttons from
> > > +              * BTN_DPAD_UP..BTN_DPAD_RIGHT and KEY_ALS_TOGGLE is the next
> > > +              * defined. */
> > > +             for (i = KEY_OK; i < BTN_DPAD_UP; i++)
> > > +                     __set_bit(i, kbd->keybit);
> > > +             for (i = KEY_ALS_TOGGLE; i <= KEY_KBD_LCD_MENU5; i++)

Changing the upper bound to KEY_BRIGHTNESS_MENU works.  That trims out
KEY_MACRO* and KEY_KBD_LCD_MENU*.

Something has to get trimmed out to bring the size down.  These are
probably less common and okay to remove, but I'm just guessing.

Regards,
Jason

Patchew 2.1-devel-0870f84

© 2016 - 2024 Red Hat, Inc.