Hi David,
On Sun, Sep 28, 2014 at 12:19:39PM +0200, David Herrmann wrote:
> Ping?
Sorry for the delay.
>
> On Wed, Aug 13, 2014 at 9:16 AM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote:
> > Hardware manufacturers group keys in the weirdest way possible. This may
> > cause a power-key to be grouped together with normal keyboard keys and
> > thus be reported on the same kernel interface.
> >
> > However, user-space is often only interested in specific sets of events.
> > For instance, daemons dealing with system-reboot (like systemd-logind)
> > listen for KEY_POWER, but are not interested in any main keyboard keys.
> > Usually, power keys are reported via separate interfaces, however,
> > some i8042 boards report it in the AT matrix. To avoid waking up those
> > system daemons on each key-press, we had two ideas:
> > - split off KEY_POWER into a separate interface unconditionally
> > - allow filtering a specific set of events on evdev FDs
> >
> > Splitting of KEY_POWER is a rather weird way to deal with this and may
> > break backwards-compatibility. It is also specific to KEY_POWER and might
> > be required for other stuff, too. Moreover, we might end up with a huge
> > set of input-devices just to have them properly split.
> >
> > Hence, this patchset implements the second idea: An event-mask to specify
> > which events you're interested in. Two ioctls allow setting this mask for
> > each event-type. If not set, all events are reported. The type==0 entry is
> > used same as in EVIOCGBIT to set the actual EV_* mask of filtered events.
> > This way, you have a two-level filter.
> >
> > We are heavily forward-compatible to new event-types and event-codes. So
> > new user-space will be able to run on an old kernel which doesn't know the
> > given event-codes or event-types.
> >
> > Acked-by: Peter Hutterer <peter.hutterer@xxxxxxxxx>
> > Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
> > ---
> > Hi Dmitry
> >
> > We could really make use of this for SUSPEND/POWER key handling. We keep getting
> > reports from people where those keys are reported as part of the main keyboard.
> > It's really annoying if we have to wake up those processes for *every*
> > key-press.
> >
> > In case you just need time to review it, let me know. Otherwise, I will keep
> > resending it as people ask me for it all the time.
> >
> > Thanks
> > David
> >
> > drivers/input/evdev.c | 156 ++++++++++++++++++++++++++++++++++++++++++++-
> > include/uapi/linux/input.h | 56 ++++++++++++++++
> > 2 files changed, 210 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> > index fd325ec..6386882 100644
> > --- a/drivers/input/evdev.c
> > +++ b/drivers/input/evdev.c
> > @@ -51,10 +51,130 @@ struct evdev_client {
> > struct list_head node;
> > int clkid;
> > bool revoked;
> > + unsigned long *evmasks[EV_CNT];
> > unsigned int bufsize;
> > struct input_event buffer[];
> > };
> >
> > +static size_t evdev_get_mask_cnt(unsigned int type)
> > +{
> > + static size_t counts[EV_CNT] = {
> > + /* EV_SYN==0 is EV_CNT, _not_ SYN_CNT, see EVIOCGBIT */
> > + [EV_SYN] = EV_CNT,
> > + [EV_KEY] = KEY_CNT,
> > + [EV_REL] = REL_CNT,
> > + [EV_ABS] = ABS_CNT,
> > + [EV_MSC] = MSC_CNT,
> > + [EV_SW] = SW_CNT,
> > + [EV_LED] = LED_CNT,
> > + [EV_SND] = SND_CNT,
> > + [EV_FF] = FF_CNT,
> > + };
> > +
> > + return (type < EV_CNT) ? counts[type] : 0;
> > +}
> > +
> > +/* must be called with evdev-mutex held */
> > +static int evdev_set_mask(struct evdev_client *client,
> > + unsigned int type,
> > + const void __user *codes,
> > + u32 codes_size)
> > +{
> > + unsigned long flags, *mask, *oldmask;
> > + size_t cnt, size;
> > +
> > + /* unknown masks are simply ignored for forward-compat */
> > + cnt = evdev_get_mask_cnt(type);
> > + if (!cnt)
> > + return 0;
> > +
> > + /* we allow 'codes_size > size' for forward-compat */
> > + size = sizeof(unsigned long) * BITS_TO_LONGS(cnt);
> > +
> > + mask = kzalloc(size, GFP_KERNEL);
> > + if (!mask)
> > + return -ENOMEM;
> > +
> > + if (copy_from_user(mask, codes, min_t(size_t, codes_size, size))) {
> > + kfree(mask);
> > + return -EFAULT;
> > + }
> > +
> > + spin_lock_irqsave(&client->buffer_lock, flags);
> > + oldmask = client->evmasks[type];
> > + client->evmasks[type] = mask;
> > + spin_unlock_irqrestore(&client->buffer_lock, flags);
> > +
> > + kfree(oldmask);
> > +
> > + return 0;
> > +}
> > +
> > +/* must be called with evdev-mutex held */
> > +static int evdev_get_mask(struct evdev_client *client,
> > + unsigned int type,
> > + void __user *codes,
> > + u32 codes_size)
> > +{
> > + unsigned long *mask;
> > + size_t cnt, size, min, i;
> > + u8 __user *out;
> > +
> > + /* we allow unknown types and 'codes_size > size' for forward-compat */
> > + cnt = evdev_get_mask_cnt(type);
> > + size = sizeof(unsigned long) * BITS_TO_LONGS(cnt);
> > + min = min_t(size_t, codes_size, size);
> > +
> > + if (cnt > 0) {
> > + mask = client->evmasks[type];
> > + if (mask) {
> > + if (copy_to_user(codes, mask, min))
> > + return -EFAULT;
I do not think this will work on big-endian setups with 64 bit kernel
and 32 bits userspace. We already have bits_to_user(), we shoudl use
them here. And I guess we need bits_from_user() to fetch bits from
userspace into kernel.
I also tried changing verbage on the ioctls, see if you agree with the
changes and if so please incorporate in your next version.
Thanks.
--
Dmitry
diff -u b/drivers/input/evdev.c b/drivers/input/evdev.c
--- b/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -71,7 +71,7 @@
[EV_FF] = FF_CNT,
};
- return (type < EV_CNT) ? counts[type] : 0;
+ return type < EV_CNT ? counts[type] : 0;
}
/* must be called with evdev-mutex held */
@@ -132,7 +132,7 @@
return -EFAULT;
} else {
/* fake mask with all bits set */
- out = (u8 __user*)codes;
+ out = (u8 __user *)codes;
for (i = 0; i < min; ++i) {
if (put_user((u8)0xff, out + i))
return -EFAULT;
diff -u b/include/uapi/linux/input.h b/include/uapi/linux/input.h
--- b/include/uapi/linux/input.h
+++ b/include/uapi/linux/input.h
@@ -161,53 +161,59 @@
#define EVIOCREVOKE _IOW('E', 0x91, int) /* Revoke device access */
/**
- * EVIOCGMASK - Retrieve current event-mask
+ * EVIOCGMASK - Retrieve current event mask
*
- * This retrieves the current event-mask for a specific event-type. The
- * argument must be of type "struct input_mask" and specifies the event-type to
- * query, the receive buffer and the size of the receive buffer.
- *
- * The event-mask is a per-client mask that specifies which events are forwarded
- * to the client. Each event-code is represented by a single bit in the
- * event-mask. If the bit is set, the event is passed to the client normally.
- * Otherwise, the event is filtered and and will never be queued on the
- * client's receive buffer.
- * Event-masks do not affect global state of an input-device. They only affect
- * the open-file they're applied on. Each open-file (i.e, file-description) can
- * have a different event-mask.
- *
- * The default event-mask for a client has all bits set, i.e. all events are
- * forwarded to the client. If a kernel is queried for an unknown event-type
- * or if the receive buffer is larger than the number of event-codes known to
- * the kernel, the kernel returns all zeroes for those codes.
+ * This ioctl allows user to retrieve the current event mask for specific
+ * event type. The argument must be of type "struct input_mask" and
+ * specifies the event type to query, the address of the receive buffer and
+ * the size of the receive buffer.
+ *
+ * The event mask is a per-client mask that specifies which events are
+ * forwarded to the client. Each event code is represented by a single bit
+ * in the event mask. If the bit is set, the event is passed to the client
+ * normally. Otherwise, the event is filtered and will never be queued on
+ * the client's receive buffer.
+ *
+ * Event masks do not affect global state of the input device. They only
+ * affect the file descriptor they are applied to.
+ *
+ * The default event mask for a client has all bits set, i.e. all events
+ * are forwarded to the client. If kernel is queried for an unknown
+ * event type or if the receive buffer is larger than the number of
+ * event codes known to the kernel, the kernel returns all zeroes for those
+ * codes.
*
* At maximum, codes_size bytes are copied.
*
- * This ioctl may fail with ENODEV in case the file is revoked, EFAULT
- * if the receive-buffer points to invalid memory, or EINVAL if the kernel
- * does not implement the ioctl.
+ * This ioctl may fail with ENODEV in case the descriptor is revoked,
+ * EFAULT if the receive buffer points to invalid memory, or EINVAL if the
+ * kernel does not implement the ioctl.
*/
+
#define EVIOCGMASK _IOR('E', 0x92, struct input_mask) /* Get event-masks */
/**
- * EVIOCSMASK - Set event-mask
+ * EVIOCSMASK - Set event mask
*
- * This is the counterpart to EVIOCGMASK. Instead of receiving the current
- * event-mask, this changes the client's event-mask for a specific type. See
- * EVIOCGMASK for a description of event-masks and the argument-type.
- *
- * This ioctl provides full forward-compatibility. If the passed event-type is
- * unknown to the kernel, or if the number of codes is bigger than known to the
- * kernel, the ioctl is still accepted and applied. However, any unknown codes
- * are left untouched and stay cleared. That means, the kernel always filters
- * unknown codes regardless of what the client requests.
- * If the new mask doesn't cover all known event-codes, all remaining codes are
- * automatically cleared and thus filtered.
+ * This ioctl is the counterpart to EVIOCGMASK. Instead of receiving the
+ * current event mask, this changes the client's event mask for a specific
+ * type. See EVIOCGMASK for a description of event-masks and the
+ * argument-type.
+ *
+ * This ioctl provides full forward compatibility. If the passed event type
+ * is unknown to the kernel, or if the number of event codes specified in
+ * the mask is bigger than what is known to the kernel, the ioctl is still
+ * accepted and applied. However, any unknown codes are left untouched and
+ * stay cleared. That means, the kernel always filters unknown codes
+ * regardless of what the client requests. If the new mask doesn't cover
+ * all known event-codes, all remaining codes are automatically cleared and
+ * thus filtered.
*
* This ioctl may fail with ENODEV in case the file is revoked. EFAULT is
- * returned if the receive-buffer points to invalid memory. EINVAL is returned
- * if the kernel does not implement the ioctl.
+ * returned if the receive-buffer points to invalid memory. EINVAL is
+ * returned if the kernel does not implement the ioctl.
*/
+
#define EVIOCSMASK _IOW('E', 0x93, struct input_mask) /* Set event-masks */
#define EVIOCSCLOCKID _IOW('E', 0xa0, int) /* Set clockid to be used for timestamps */
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