Revert commits

92af4dcb ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a404 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e ("timekeeping: Remove boot time specific code")
f2d6fdbf ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449a ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320 ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
  of suspending (Genki Sky).  [Verified that that's because systemd uses
  CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
  systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
  (Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
  after resume 50% of the time (Pavel).  [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
  system resume (Pavel).

* Full system hang during resume (me).  [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.
Reported-by: NRafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

Now that the MONOTONIC and BOOTTIME clocks are indentical, remove all the
special casing.

The user space visible interfaces still support both clocks, but their behavior
is identical.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-input@vger.kernel.org
Link: http://lkml.kernel.org/r/20180301165150.155899327@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The input events use struct timeval to store event time, unfortunately
this structure is not y2038 safe and is being replaced in kernel with
y2038 safe structures.

Because of ABI concerns we can not change the size or the layout of
structure input_event, so we opt to re-interpreting the 'seconds' part
of timestamp as an unsigned value, effectively doubling the range of
values, to year 2106.

Newer glibc that has support for 32 bit applications to use 64 bit
time_t supplies __USE_TIME_BITS64 define [1], that we can use to present
the userspace with updated input_event layout. The updated layout will
cause the compile time breakage, alerting applications and distributions
maintainers to the issue. Existing 32 binaries will continue working
without any changes until 2038.

Ultimately userspace applications should switch to using monotonic or
boot time clocks, as realtime clock is not very well suited for input
event timestamps as it can go backwards (see a80b83b7 "Input: evdev -
add CLOCK_BOOTTIME support" by by John Stultz). With monotonic clock the
practical range of reported times will always fit into the pair of 32
bit values, as we do not expect any system to stay up for a hundred
years without a single reboot.

[1] https://sourceware.org/glibc/wiki/Y2038ProofnessDesignSuggested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: NPeter Hutterer <peter.hutterer@who-t.net>
Patchwork-Id: 10148083
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Replace the open coded registration of the cdev and dev with the
new device_add_cdev() helper in evdev, joydev and mousedev. The helper
replaces a common pattern by taking the proper reference against the
parent device and adding both the cdev and the device.
Signed-off-by: NLogan Gunthorpe <logang@deltatee.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

clk_type and clkid stores different predefined clock identification
values so they cannot be compared for checking duplicate clock change
request. Therefore, lets fix it to avoid unexpected results.
Signed-off-by: NAniroop Mathur <a.mathur@samsung.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

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.
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

We've got bug reports showing the old systemd-logind (at least
system-210) aborting unexpectedly, and this turned out to be because
of an invalid error code from close() call to evdev devices.  close()
is supposed to return only either EINTR or EBADFD, while the device
returned ENODEV.  logind was overreacting to it and decided to kill
itself when an unexpected error code was received.  What a tragedy.

The bad error code comes from flush fops, and actually evdev_flush()
returns ENODEV when device is disconnected or client's access to it is
revoked. But in these cases the fact that flush did not actually happen is
not an error, but rather normal behavior. For non-disconnected devices
result of flush is also not that interesting as there is no potential of
data loss and even if it fails application has no way of handling the
error. Because of that we are better off always returning success from
evdev_flush().

Also returning EINTR from flush()/close() is discouraged (as it is not
clear how application should handle this error), so let's stop taking
evdev->mutex interruptibly.

Bugzilla: http://bugzilla.suse.com/show_bug.cgi?id=939834
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Use kvfree() instead of open-coding it.
Signed-off-by: NPekka Enberg <penberg@kernel.org>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

There is no point in queueing EV_SYN/SYN_DROPPED on clock type change when
there are no events in the client's queue and doing so confuses tests in
libinput package, so let's not do that.
Reported-and-tested-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

When client changes the type of clock used for the time stamps in input
events flush pending events from the client's queue (since client would not
know which events have old time stamps and which ones have new ones) and
and queue SYN_DROPPED event.
Signed-off-by: NAnshul Garg <anshul.g@samsung.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

This patch adds support for CLOCK_BOOTTIME for input event timestamp.
CLOCK_BOOTTIME includes suspend time, so it would allow aplications
to get correct time difference between two events even when system
resumes from suspend state.
Signed-off-by: NAniroop Mathur <a.mathur@samsung.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

If kzalloc() failed and then evdev_open_device() fails, evdev_open()
will pass a vmalloc'ed pointer to kfree.

This might fix https://bugzilla.kernel.org/show_bug.cgi?id=88401, where
there was a crash in kfree().
Reported-by: NChristian Casteyde <casteyde.christian@free.fr>
Belatedly-Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Henrik Rydberg <rydberg@euromail.se>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The 'max' size passed into the function is measured in number of bits
(KEY_MAX, LED_MAX, etc) so we need to convert it accordingly before trying
to copy the data out, otherwise we will try copying too much and end up
with up with a page fault.
Reported-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Convert the monotonic timestamp with ktime_mono_to_real() in
evdev_events().

In evdev_queue_syn_dropped() we can call either ktime_get() or
ktime_get_real() depending on the clkid. No point in having two calls
for CLOCK_REALTIME.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

We put this workaround in 2008 and the offending userspace has been fixed
up long time ago; the link in the message is no longer valid either, so it
is time to retire it.
Reviewed-by: NPeter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

If a new (id == -1) ff effect was uploaded from userspace,
ff-core.c::input_ff_upload() will have assigned a positive number to the
new effect id.  Currently, evdev.c::evdev_do_ioctl() will save this new id
to userspace, regardless of whether the upload succeeded or not.

On upload failure, this can be confusing because the dev->ff->effects[]
array will not contain an element at the index of that new effect id.

This patch fixes this by leaving the id unchanged after upload fails.

Note: Unfortunately applications should still expect changed effect id for
quite some time.

This has been discussed on:
http://www.mail-archive.com/linux-input@vger.kernel.org/msg08513.html
("ff-core effect id handling in case of a failed effect upload")
Suggested-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NElias Vanderstuyft <elias.vds@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

evdev always tries to allocate the event buffer for clients using
kzalloc rather than vmalloc, presumably to avoid mapping overhead where
possible.  However, drivers like bcm5974, which claims support for
reporting 16 fingers simultaneously, can have an extraordinarily large
buffer.  The resultant contiguous order-4 allocation attempt fails due
to fragmentation, and the device is thus unusable until reboot.

Try kzalloc if we can to avoid the mapping overhead, but if that fails,
fall back to vzalloc.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

If we have multiple sessions on a system, we normally don't want
background sessions to read input events. Otherwise, it could capture
passwords and more entered by the user on the foreground session. This is
a real world problem as the recent XMir development showed:
  http://mjg59.dreamwidth.org/27327.html

We currently rely on sessions to release input devices when being
deactivated. This relies on trust across sessions. But that's not given on
usual systems. We therefore need a way to control which processes have
access to input devices.

With VTs the kernel simply routed them through the active /dev/ttyX. This
is not possible with evdev devices, though. Moreover, we want to avoid
routing input-devices through some dispatcher-daemon in userspace (which
would add some latency).

This patch introduces EVIOCREVOKE. If called on an evdev fd, this revokes
device-access irrecoverably for that *single* open-file. Hence, once you
call EVIOCREVOKE on any dup()ed fd, all fds for that open-file will be
rather useless now (but still valid compared to close()!). This allows us
to pass fds directly to session-processes from a trusted source. The
source keeps a dup()ed fd and revokes access once the session-process is
no longer active.
Compared to the EVIOCMUTE proposal, we can avoid the CAP_SYS_ADMIN
restriction now as there is no way to revive the fd again. Hence, a user
is free to call EVIOCREVOKE themself to kill the fd.

Additionally, this ioctl allows multi-layer access-control (again compared
to EVIOCMUTE which was limited to one layer via CAP_SYS_ADMIN). A middle
layer can simply request a new open-file from the layer above and pass it
to the layer below. Now each layer can call EVIOCREVOKE on the fds to
revoke access for all layers below, at the expense of one fd per layer.

There's already ongoing experimental user-space work which demonstrates
how it can be used:
  http://lists.freedesktop.org/archives/systemd-devel/2013-August/012897.htmlSigned-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

If userspace requests current KEY-state, they very likely assume that no
such events are pending in the output queue of the evdev device.
Otherwise, they will parse events which they already handled via
EVIOCGKEY(). For XKB applications this can cause irreversible keyboard
states if a modifier is locked multiple times because a CTRL-DOWN event is
handled once via EVIOCGKEY() and once from the queue via read(), even
though it should handle it only once.

Therefore, lets do the only logical thing and flush the evdev queue
atomically during this ioctl. We only flush events that are affected by
the given ioctl.

This only affects boolean events like KEY, SND, SW and LED. ABS, REL and
others are not affected as duplicate events can be handled gracefully by
user-space.

Note: This actually breaks semantics of the evdev ABI. However,
investigations showed that userspace already expects the new semantics and
we end up fixing at least all XKB applications.
All applications that are aware of this race-condition mirror the KEY
state for each open-file and detect/drop duplicate events. Hence, they do
not care whether duplicates are posted or not and work fine with this fix.

Also note that we need proper locking to guarantee atomicity and avoid
dead-locks. event_lock must be locked before queue_lock (see input-core).
However, we can safely release event_lock while flushing the queue. This
allows the input-core to proceed with pending events and only stop if it
needs our queue_lock to post new events.
This should guarantee that we don't block event-dispatching for too long
while flushing a single event queue.
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Acked-by: NPeter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Commit 7f8d4cad ("Input: extend the number of event (and other)
devices") made evdev, joydev and mousedev to embed struct cdev into
their respective structures representing input devices.

Unfortunately character device structure may outlive the parent
structure unless we do not set it up as parent of character device so
that it will stay pinned until character device is freed.

Also, now that parent structure is pinned while character device exists
we do not need to pin and unpin it every time user opens or closes it.
Reported-by: NDave Jones <davej@redhat.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extend the amount of character devices, such as eventX, mouseX and jsX,
from a hard limit of 32 per input handler to about 1024 shared across
all handlers.

To be compatible with legacy installations input handlers will start
creating char devices with minors in their legacy range, however once
legacy range is exhausted they will start allocating minors from the
dynamic range 256-1024.
Reviewed-by: NDavid Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

By sending a full frame of events at the same time, the irqsoff
latency at heavy load is brought down from 200 us to 100 us.

Cc: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: NBenjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: NPing Cheng <pingc@wacom.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>

Move all MT-related things to a separate place. This saves some
bytes for non-mt input devices, and prepares for new MT features.
Reviewed-and-tested-by: NBenjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: NPing Cheng <pingc@wacom.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>

According to the standard count 0 is special - no IO should happen but we
can check error conditions (device gone away, etc), and return 0 if there
are no errors. We used to return -EINVAL instead and we also could return 0
if an event was "stolen" by another thread.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

We should use rcu_dereference_protected() when checking if given client
is the one that grabbed the device. This fixes warnings produced by
sparse.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Commit 509f87c5 (evdev - do not block waiting for an event if fd
is nonblock) created a code path were it was possible to use retval
uninitialized.

This could lead to the xorg evdev input driver getting corrupt data
and refusing to work with log messages like
	AUO-Pixcir touchscreen: Read error: Success
	sg060_keys: Read error: Success
	AUO-Pixcir touchscreen: Read error: Success
	sg060_keys: Read error: Success
(for drivers auo-pixcir-ts and gpio-keys).
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Acked-by: NDima Zavin <dima@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

This patch adds the ability to extract MT slot data via a new ioctl,
EVIOCGMTSLOTS. The function returns an array of slot values for the
specified ABS_MT event type.

Example of user space usage:

struct { unsigned code; int values[64]; } req;
req.code = ABS_MT_POSITION_X;
if (ioctl(fd, EVIOCGMTSLOTS(sizeof(req)), &req) < 0)
	return -1;
for (i = 0; i < 64; i++)
	printf("slot %d: %d\n", i, req.values[i]);
Reviewed-by: NChase Douglas <chase.douglas@canonical.com>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>

As noted by Arve and others, since wall time can jump backwards, it is
difficult to use for input because one cannot determine if one event
occurred before another or for how long a key was pressed.

However, the timestamp field is part of the kernel ABI, and cannot be
changed without possibly breaking existing users.

This patch adds a new IOCTL that allows a clockid to be set in the
evdev_client struct that will specify which time base to use for event
timestamps (ie: CLOCK_MONOTONIC instead of CLOCK_REALTIME).

For now we only support CLOCK_MONOTONIC and CLOCK_REALTIME, but
in the future we could support other clockids if appropriate.

The default remains CLOCK_REALTIME, so we don't change the ABI.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Reviewed-by: NDaniel Kurtz <djkurtz@google.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Commit 509f87c5 (evdev - do not block waiting for an event if fd
is nonblock) created a code path were it was possible to use retval
uninitialized.

This could lead to the xorg evdev input driver getting corrupt data
and refusing to work with log messages like
	AUO-Pixcir touchscreen: Read error: Success
	sg060_keys: Read error: Success
	AUO-Pixcir touchscreen: Read error: Success
	sg060_keys: Read error: Success
(for drivers auo-pixcir-ts and gpio-keys).
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Acked-by: NDima Zavin <dima@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

If there is a full packet in the buffer, and we overflow that buffer
right after checking for that condition, it would have been possible
for us to block indefinitely (rather, until the next full packet) even if
the file was marked as O_NONBLOCK.

Cc: Jeff Brown <jeffbrown@android.com>
Signed-off-by: NDima Zavin <dima@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Signed-off-by: NDima Zavin <dima@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Without this, it was possible for the reader to get ahead of packet_head.
If the input device generated a partial packet *right* after the reader
got ahead, then we can get into a situation where the device is marked
readable, but read always returns 0 until the next packet is finished
(i.e a SYN is generated by the input driver).

This situation can also happen if we overflow the buffer while a reader
is trying to read an event out.
Signed-off-by: NDima Zavin <dima@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

We should only wake waiters on the event device when we actually post
an EV_SYN/SYN_REPORT to the queue. Otherwise we end up making waiting
threads runnable only to go right back to sleep because the device
still isn't readable.
Reported-by: NJeffrey Brown <jeffbrown@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

There is no need to call synchronize_rcu() after a list insertion,
or a NULL->ptr assignment.

However, the reverse operations do need this call.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

This patch modifies evdev so that it only becomes readable when
the buffer contains an EV_SYN/SYN_REPORT event.

On SMP systems, it is possible for an evdev client blocked on poll()
to wake up and read events from the evdev ring buffer at the same
rate as they are enqueued.  This can result in high CPU usage,
particularly for MT devices, because the client ends up reading
events one at a time instead of reading complete packets.

We eliminate this problem by making the device readable only when
the buffer contains at least one complete packet.  This causes
clients to block until the entire packet is available.
Signed-off-by: NJeff Brown <jeffbrown@android.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Add a new EV_SYN code, SYN_DROPPED, to inform the client when input
events have been dropped from the evdev input buffer due to a
buffer overrun.  The client should use this event as a hint to
reset its state or ignore all following events until the next
packet begins.
Signed-off-by: NJeff Brown <jeffbrown@android.com>
[dtor@mail.ru: Implement Henrik's suggestion and drop old events in
 case of overflow.]
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

As was recently brought up on the busybox list
(http://lists.busybox.net/pipermail/busybox/2011-January/074565.html),
evdev_write doesn't properly check the count argument, which will
lead to a return value > count on partial writes if the remaining bytes
are accessible - causing userspace confusion.

Fix it by only handling each full input_event structure and return -EINVAL
if less than 1 struct was written, similar to how it is done in evdev_read.
Reported-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Acked-by: NHenrik Rydberg <rydberg@euromail.se>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Today, userspace sets up an input device based on the data it emits.
This is not always enough; a tablet and a touchscreen may emit exactly
the same data, for instance, but the former should be set up with a
pointer whereas the latter does not need to. Recently, a new type of
touchpad has emerged where the buttons are under the pad, which
changes logic without changing the emitted data. This patch introduces
a new ioctl, EVIOCGPROP, which enables user access to a set of device
properties useful during setup. The properties are given as a bitmap
in the same fashion as the event types, and are also made available
via sysfs, uevent and /proc/bus/input/devices.
Acked-by: NPing Cheng <pingc@wacom.com>
Acked-by: NChase Douglas <chase.douglas@canonical.com>
Acked-by: NDmitry Torokhov <dtor@mail.ru>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>