linux-toradex.git/drivers/tty/ipwireless/tty.c, branch v4.9.16

tty: ipwireless, cleanup TIOCGSERIAL

2016-06-25T15:56:30+00:00

In ipwireless_get_serial_info, struct serial_struct is memset to 0 and
then some members set to 0 explicitly.

Remove the latter as it is obviously superfluous.

And remove the retinfo check against NULL. copy_to_user will take care
of that.

Part of hub6 cleanup series.

Signed-off-by: Jiri Slaby 
Cc: Jiri Kosina 
Acked-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

tty: ipwireless: Remove tty->closing abort from ipw_open()

2014-07-10T23:06:49+00:00

tty->closing cannot be set on ipw_open() because the ipwireless tty
driver does not call any functions that set tty->closing.

CC: Jiri Kosina 
Signed-off-by: Peter Hurley 
Acked-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

tty: Fix low_latency BUG

2014-03-01T00:31:00+00:00

The user-settable knob, low_latency, has been the source of
several BUG reports which stem from flush_to_ldisc() running
in interrupt context. Since 3.12, which added several sleeping
locks (termios_rwsem and buf->lock) to the input processing path,
the frequency of these BUG reports has increased.

Note that changes in 3.12 did not introduce this regression;
sleeping locks were first added to the input processing path
with the removal of the BKL from N_TTY in commit
a88a69c91256418c5907c2f1f8a0ec0a36f9e6cc,
'n_tty: Fix loss of echoed characters and remove bkl from n_tty'
and later in commit 38db89799bdf11625a831c5af33938dcb11908b6,
'tty: throttling race fix'. Since those changes, executing
flush_to_ldisc() in interrupt_context (ie, low_latency set), is unsafe.

However, since most devices do not validate if the low_latency
setting is appropriate for the context (process or interrupt) in
which they receive data, some reports are due to misconfiguration.
Further, serial dma devices for which dma fails, resort to
interrupt receiving as a backup without resetting low_latency.

Historically, low_latency was used to force wake-up the reading
process rather than wait for the next scheduler tick. The
effect was to trim multiple milliseconds of latency from
when the process would receive new data.

Recent tests [1] have shown that the reading process now receives
data with only 10's of microseconds latency without low_latency set.

Remove the low_latency rx steering from tty_flip_buffer_push();
however, leave the knob as an optional hint to drivers that can
tune their rx fifos and such like. Cleanup stale code comments
regarding low_latency.

[1] https://lkml.org/lkml/2014/2/20/434

"Yay.. thats an annoying historical pain in the butt gone."
	-- Alan Cox

Reported-by: Beat Bolli 
Reported-by: Pavel Roskin 
Acked-by: David Sterba 
Cc: Grant Edwards 
Cc: Stanislaw Gruszka 
Cc: Hal Murray 
Cc:  # 3.12.x+
Signed-off-by: Peter Hurley 
Signed-off-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

tty: delete non-required instances of include

2014-01-08T01:05:21+00:00

None of these files are actually using any __init type directives
and hence don't need to include .  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_flip_buffer_push

2013-01-16T06:30:15+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: move low_latency to tty_port

2013-01-16T06:23:16+00:00

One point is to have less places where we actually need tty pointer.
The other is that low_latency is bound to buffer processing and
buffers are now in tty_port. So it makes sense to move low_latency to
tty_port too.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_string

2013-01-16T06:22:35+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: call tty_port_destroy in the rest of drivers

2012-11-16T01:20:58+00:00

After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue. So fix the drivers to fulfil this
assumption.

To be sure, the TTY buffers (and later some stuff) are gone along with
the tty_port, we have to call tty_port_destroy at tear-down places.
This is mostly where the structure containing a tty_port is freed.
This patch does exactly that -- put tty_port_destroy at those places.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: use tty_port_register_device

2012-08-13T23:50:19+00:00

Currently we have no way to assign tty->port while performing tty
installation. There are two ways to provide the link tty_struct =>
tty_port. Either by calling tty_port_install from tty->ops->install or
tty_port_register_device called instead of tty_register_device when
the device is being set up after connected.

In this patch we modify most of the drivers to do the latter. When the
drivers use tty_register_device and we have tty_port already, we
switch to tty_port_register_device. So we have the tty_struct =>
tty_port link for free for those.

Signed-off-by: Jiri Slaby 
Acked-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

TTY: ipwireless, use tty from tty_port

2012-04-09T18:30:39+00:00

It does not make the driver less racy though. Close and hangup should
be rewritten and tty refcounting used properly.

Signed-off-by: Jiri Slaby 
Cc: Jiri Kosina 
Acked-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman