gsm_cleanup_mux() is called in the line discipline close path which
is called at tty_release() time. At this stage the tty is no longer
operational enough to send any frames. Sending close frames is
therefore not possible and waiting for their answers always times
out.
This patch removes sending close messages and waiting for their answers
from the tty_release path.
This patch makes explicit what previously implicitly had been the case
already: We are not able to tell the modem that we are about to close
the multiplexer on our side. This means the modem will stay in
multiplexer mode and re-establishing the multiplexer later fails. The
only way for userspace to work around this is to manually send a close
frame in N_TTY mode after closing the mux.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is not a very good practice to define the IOCTL manually instead of
using the header file.
Fix it on the documentation example.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Pull tty and serial driver updates from Greg KH:
"Here's the large TTY and Serial driver update for 4.7-rc1.
A few new serial drivers are added here, and Peter has fixed a bunch
of long-standing bugs in the tty layer and serial drivers as normal.
Full details in the shortlog.
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (88 commits)
MAINTAINERS: 8250: remove website reference
serial: core: Fix port mutex assert if lockdep disabled
serial: 8250_dw: fix wrong logic in dw8250_check_lcr()
tty: vt, finish looping on duplicate
tty: vt, return error when con_startup fails
QE-UART: add "fsl,t1040-ucc-uart" to of_device_id
serial: mctrl_gpio: Drop support for out1-gpios and out2-gpios
serial: 8250dw: Add device HID for future AMD UART controller
Fix OpenSSH pty regression on close
serial: mctrl_gpio: add IRQ locking
serial: 8250: Integrate Fintek into 8250_base
serial: mps2-uart: add support for early console
serial: mps2-uart: add MPS2 UART driver
dt-bindings: document the MPS2 UART bindings
serial: sirf: Use generic uart-has-rtscts DT property
serial: sirf: Introduce helper variable struct device_node *np
serial: mxs-auart: Use generic uart-has-rtscts DT property
serial: imx: Use generic uart-has-rtscts DT property
doc: DT: Add Generic Serial Device Tree Bindings
serial: 8250: of: Make tegra_serial_handle_break() static
...
As of commit ebd2c8f6d2 ("serial: kill off uart_info"), the
circular transmission buffer is part of struct uart_state instead of
struct uart_info. Make it clear this structure is pointed to from struct
uart_port.
Change 'circ' to 'circ_buf' to match the structure name while we're at
it.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Stop referring to the mutex member of the tty_port struct as
'port->mutex', as 'port' is ambiguous, and usually refers to the
uart_port struct in this document. Use 'tty_port->mutex' instead,
following the single existing use.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
break_ctl() is not called from any sort of atomic context, so there is no
problem with it sleeping.
Reported-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Document that .(un)throttle() are serialized with each other, and with
termios modification by the tty layer.
Reported-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Document that .throttle() and .unthrottle() are relevant only if
hardware assisted flow control is enabled.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit 834392a7d9 ("serial: doc: Un-document non-existing
uart_write_console()") removed a paragraph about a helper function that
seemed to never exist.
Peter Hurley pointed out that the function does exist, but is called
differently. Re-add the paragraph, with the function name corrected.
Fixes: 834392a7d9 ("serial: doc: Un-document non-existing uart_write_console()")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Note that mutex_lock() should not be called with interrupts disabled.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
uart_info.tmpbuf and uart_info.tmpbuf_sem were removed in v2.6.10, in
full-history-linux commit a797ad7e3ae9cad4 ("[SERIAL] Clean up
serial_core.c write functions.").
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
uart_write_console() never existed, not even when the "new
uart_write_console function" was documented.
Fixes: 67ab7f596b ("[SERIAL] Update serial driver documentation")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The chars_in_buffer() line discipline method serves no functional
purpose, other than as a (dubious) debugging aid for mostly bit-rotting
drivers. Despite being documented as an optional method, every caller
is unconditionally executed (although conditionally compiled).
Furthermore, direct tty->ldisc access without an ldisc ref is unsafe.
Lastly, N_TTY's chars_in_buffer() has warned of removal since 3.12.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Mention that the ldisc open method must set tty->receive_room, and
that many methods are optional. Add description of receive_buf2 method.
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit a5f276f10f (serial_core: Handle TIOC[GS]RS485 ioctls.,
2014-11-06) serial_core handles RS485 ioctls. Drivers only need to implement
the rs485_config callback. Update serial-rs485.txt to reflect these changes.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A read() from a pty master may mistakenly indicate EOF (errno == -EIO)
after the pty slave has closed, even though input data remains to be read.
For example,
pty slave | input worker | pty master
| |
| | n_tty_read()
pty_write() | | input avail? no
add data | | sleep
schedule worker --->| | .
|---> flush_to_ldisc() | .
pty_close() | fill read buffer | .
wait for worker | wakeup reader --->| .
| read buffer full? |---> input avail ? yes
|<--- yes - exit worker | copy 4096 bytes to user
TTY_OTHER_CLOSED <---| |<--- kick worker
| |
**** New read() before worker starts ****
| | n_tty_read()
| | input avail? no
| | TTY_OTHER_CLOSED? yes
| | return -EIO
Several conditions are required to trigger this race:
1. the ldisc read buffer must become full so the input worker exits
2. the read() count parameter must be >= 4096 so the ldisc read buffer
is empty
3. the subsequent read() occurs before the kicked worker has processed
more input
However, the underlying cause of the race is that data is pipelined, while
tty state is not; ie., data already written by the pty slave end is not
yet visible to the pty master end, but state changes by the pty slave end
are visible to the pty master end immediately.
Pipeline the TTY_OTHER_CLOSED state through input worker to the reader.
1. Introduce TTY_OTHER_DONE which is set by the input worker when
TTY_OTHER_CLOSED is set and either the input buffers are flushed or
input processing has completed. Readers/polls are woken when
TTY_OTHER_DONE is set.
2. Reader/poll checks TTY_OTHER_DONE instead of TTY_OTHER_CLOSED.
3. A new input worker is started from pty_close() after setting
TTY_OTHER_CLOSED, which ensures the TTY_OTHER_DONE state will be
set if the last input worker is already finished (or just about to
exit).
Remove tty_flush_to_ldisc(); no in-tree callers.
Fixes: 52bce7f8d4 ("pty, n_tty: Simplify input processing on final close")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96311
BugLink: http://bugs.launchpad.net/bugs/1429756
Cc: <stable@vger.kernel.org> # 3.19+
Reported-by: Andy Whitcroft <apw@canonical.com>
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
