linux-toradex.git/drivers/input/evdev.c, branch v3.11-rc5

Input: evdev - flush queues during EVIOCGKEY-like ioctls

2013-06-10T05:35:05+00:00

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: David Herrmann 
Acked-by: Peter Hutterer 
Signed-off-by: Dmitry Torokhov

Input: fix use-after-free introduced with dynamic minor changes

2012-10-22T05:50:37+00:00

Commit 7f8d4cad1e4e ("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: Dave Jones 
Signed-off-by: Dmitry Torokhov 
Acked-by: Al Viro 
Signed-off-by: Linus Torvalds

Input: extend the number of event (and other) devices

2012-10-08T16:37:55+00:00

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: David Herrmann 
Signed-off-by: Dmitry Torokhov

Input: evdev - Add the events() callback

2012-09-19T17:50:18+00:00

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 
Tested-by: Benjamin Tissoires 
Tested-by: Ping Cheng 
Acked-by: Dmitry Torokhov 
Signed-off-by: Henrik Rydberg

Input: Break out MT data

2012-09-19T17:50:17+00:00

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: Benjamin Tissoires 
Tested-by: Ping Cheng 
Acked-by: Dmitry Torokhov 
Signed-off-by: Henrik Rydberg

Input: evdev - properly handle read/write with count 0

2012-05-02T07:23:58+00:00

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: Dmitry Torokhov

Input: evdev - properly access RCU-protected 'grab' data

2012-05-02T07:23:14+00:00

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: Dmitry Torokhov

Merge branch 'next' into for-linus

2012-03-20T00:02:01+00:00

Merge branch 'for-next' of github.com:rydberg/linux into next

2012-03-09T18:56:35+00:00

Merge commit 'v3.3-rc6' into next

2012-03-09T18:55:17+00:00