When CONFIG_PCI is unset, we see these warnings in rocket:
drivers/tty/rocket.c:3140:13: warning: 'rmSpeakerReset' defined but not used
drivers/tty/rocket.c:2599:12: warning: 'sPCIInitController' defined but not used
Fix those by moving the functions to one place and make them depend on
CONFIG_PCI.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Toralf Foerster <toralf.foerster@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure to check ASYNC_INITIALISED before raising DTR when waking up
from blocked open in block_til_ready.
Currently DTR could get raised at hang up as a blocked process would
raise DTR unconditionally before checking for hang up and returning.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure to check ASYNC_INITIALISED before raising DTR when waking up
from blocked open in block_til_ready.
Currently DTR could get raised at hang up as a blocked process would
raise DTR unconditionally before checking for hang up and returning.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure to check ASYNC_INITIALISED before raising DTR when waking up
from blocked open in block_til_ready.
Currently DTR could get raised at hang up as a blocked process would
raise DTR unconditionally before checking for hang up and returning.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This fixes the stub for dw8250_probe_acpi() that is used
when compiling without ACPI enabled. The argument type was
wrong.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Designware UART has an optional support for 16750
compatible Auto Flow Control. This will enable it based on
the AFCE bit in Component Parameter Register.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The new ACPI DMA helpers in dmaengine API can take care of
extracting all the necessary information regarding DMA. The
driver does not need to do this separately any more.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Lynxpoint LPSS peripheral clocks are now handled in clk
framework so the drivers do not need to take care of them
manually. In dw8250_probe_acpi(), the uartclk is now taken
from the driver_data only if it was not already set.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This allows ACPI to put the device to D3 when it's not used.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some slave channel parameters will be always the same. For
example, direction for the Rx channel will always be
DMA_DEV_TO_MEM and DMA_MEM_TO_DEV for Tx channel.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The helper functions in dmaengine API allow the drivers to
request slave channels without the filter parameters. They
will attempt to extract the needed DMA client information
from DT or ACPI, but if such information is not available
the filter parameters can still be used.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Overrun, parity and framing errors should be handled in
8250_core. This also adds check for the dma_status and exits
if the channel is not idle.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Removing one unneeded uart_write_wakeup(). There is no need
to start PIO transfer unless DMA fails, so this also changes
serial8250_tx_dma() to return 0 unless that is the case.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a few bugs in the samsung serial driver when built as a
loadable module, which makes the console code unavailable, as well as
giving no access to the 'printascii' early debug function. This adds
the appropriate compile time conditionals.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The registers for the Samsung S3C serial port are currently defined in
the platform specific arch/arm/plat-samsung/include/plat/regs-serial.h
file, which is not visible to multiplatform capable drivers.
Unfortunately, it is not possible to move the file into a more local
place as we should normally try to, because the same registers
may be used in one of four places:
* In the driver itself
* In platform-independent ARM code for early debug output
* In platform_data definitions
* In the Samsung platform power management code
I have also found no way to logically split out a platform_data
file, other than possibly move everything into
include/linux/platform_data, which also felt wrong. The only
part of this file that makes sense to keep specific to the s3c24xx
platform are the virtual and physical addresses defined here,
which are needed in no other location.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With the common clock interface, there is no way to provide the
"clock_source" sysfs attribute for the samsung serial ports. Given that
this file was purely informational and had fixed contents, we have reason
to believe that no user space programs were relying on it.
The sysfs file is not documented in the ABI docs.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As Ilya Zykov identified in his patch 'PROBLEM: Race condition in
tty buffer's function flush_to_ldisc()', a race condition exists
which allows a parallel flush_to_ldisc() to flush and free the tty
flip buffers while those buffers are in-use. For example,
CPU 0 | CPU 1 | CPU 2
| flush_to_ldisc() |
| grab spin lock |
tty_buffer_flush() | | flush_to_ldisc()
wait for spin lock | | wait for spin lock
| if (!test_and_set_bit(TTYP_FLUSHING)) |
| while (next flip buffer) |
| ... |
| drop spin lock |
grab spin lock | |
if (test_bit(TTYP_FLUSHING)) | |
set_bit(TTYP_FLUSHPENDING) | receive_buf() |
drop spin lock | |
| | grab spin lock
| | if (!test_and_set_bit(TTYP_FLUSHING))
| | if (test_bit(TTYP_FLUSHPENDING))
| | __tty_buffer_flush()
CPU 2 has just flushed and freed all tty flip buffers while CPU 1 is
transferring data from the head flip buffer.
The original patch was rejected under the assumption that parallel
flush_to_ldisc() was not possible. Because of necessary changes to
the workqueue api, work items can execute in parallel on SMP.
This patch differs slightly from the original patch by testing for
a pending flush _after_ each receive_buf(), since TTYP_FLUSHPENDING
can only be set while the lock is dropped around receive_buf().
Reported-by: Ilya Zykov <linux@izyk.ru>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Ilya Zykov <linux@izyk.ru>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The only part of proc_dir_entry the code outside of fs/proc
really cares about is PDE(inode)->data. Provide a helper
for that; static inline for now, eventually will be moved
to fs/proc, along with the knowledge of struct proc_dir_entry
layout.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There is a bug in resources deallocation code in mxser_probe() and
mxser_module_init(). As soon as variable 'i' is unsigned int, cycle
termination condition i >= 0 is always true. The patch fixes the issue.
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 77e372a3d8.
Checking for disabled resources board breaks detection pnp on another
board "AMI UEFI implementation (Version: 0406 Release Date: 06/06/2012)".
I'm working with the reporter of the original bug to write and test
a better fix.
https://bugzilla.redhat.com/show_bug.cgi?id=928246
Signed-off-by: Sean Young <sean@mess.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use the wrapper functions for getting and setting the driver data using
spi_device instead of using dev_{get|set}_drvdata with &spi->dev, so we
can directly pass a struct spi_device.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With the generic DMA device tree helper supported by mxs-dma driver,
client devices only need to call dma_request_slave_channel() for
requesting a DMA channel from dmaengine.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Partially reverts 1776fd059c
that introduced regression reported by Paul Walmsley.
This commit restores setting granularity in SCR register
and adds note about comments below being inconsistent with
actual code.
Signed-off-by: Alexey Pelykh <alexey.pelykh@gmail.com>
Tested-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Following patch will fix build error if CONFIG_DMA_ENGINE is unset.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Chanho Min <chanho.min@lge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some devices have too few buttons, which it makes it hard to have
a reset combo that won't trigger automatically. As such a
timeout functionality that requires the combination to be held for
a given amount of time before triggering is introduced.
If a key combo is recognized and held for a 'timeout' amount of time,
the system triggers a reset. If the timeout value is omitted the
driver simply ignores the functionality.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
In DMA support, The received data is not pushed to tty until the DMA buffer
is filled. But some megabyte rate chips such as BT expect fast response and
data should be pushed immediately. In order to fix this issue, We suggest
the use of the timer for polling DMA buffer.
In our test, no data loss occurred at high-baudrate as compared with interrupt-
driven (We tested with 3Mbps).
We changes:
- We add timer for polling. If we set poll_timer to 10, every 10ms,
timer handler checks the residue in the dma buffer and transfer data
to the tty. Also, last_residue is updated for the next polling.
- poll_timeout is used to prevent the timer's system cost.
If poll_timeout is set to 3000 and no data is received in 3 seconds,
we inactivate poll timer and driver falls back to interrupt-driven.
When data is received again in FIFO and UART irq is occurred, we switch
back to DMA mode and start polling.
- We use consistent DMA mappings to avoid from the frequent cache operation
of the timer function for default.
- pl011_dma_rx_chars is modified. the pending size is recalculated because
data can be taken by polling.
- the polling time is adjusted if dma rx poll is enabled but no rate is
specified. Ideal polling interval to push 1 character at every interval
is the reciprocal of 'baud rate / 10 line bits per character / 1000 ms
per sec'. But It is very aggressive to system. Experimentally,
'10000000 / baud' is suitable to receive dozens of characters. the poll rate
can be specified statically by dma_rx_poll_rate of the platform data as well.
Changes compared to v1:
- Use of consistent DMA mappings.
- Added dma_rx_poll_rate in platform data to specify the polling interval.
- Added dma_rx_poll_timeout in platform data to specify the polling timeout.
Changes compared to v2:
- Use of consistent DMA mappings for default.
- Added dma_rx_poll_enable in platform data to adjust the polling time
according to the baud rate.
- remove unnecessary lock from the polling function.
Signed-off-by: Chanho Min <chanho.min@lge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit implements support for using the clk api; this lets us use
the "clocks" property with device tree, instead of having to use
clock-frequency.
Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The no_console_suspend option allows the console to write to the UART
during early resume, before the serial port itself is resumed. Such
writes hang indefinitely waiting for TX ready.
This adds a check to the console putchar function to drop characters
instead of hanging if the port hasn't been initialized. That way, we
can use no_console_suspend without risk of hanging.
Signed-off-by: Michael Spang <spang@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This closes a window where the system may hang in resume as soon as the
UART interrupt is enabled and before the mask is restored. The hang occurs
because the driver can't handle IRQs it thinks are masked.
Signed-off-by: Michael Spang <spang@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since the interrupt mask register is not preserved across system suspend
and it defaults to all interrupts enabled, it is not enough to disable
UART interrupt.
This patch adds free_irq to port shutdown and mask setting to port
startup to handle IRQ disabling in a suspend-friendly way. In addition,
a bug caused by multiple request_irq calls in port startup callback is
fixed.
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here are some tty/serial driver fixes for 3.9.
The big thing here is the fix for the huge mess we caused renaming the 8250
driver accidentally in the 3.7 kernel release, without realizing that there
were users of the module options that suddenly broke. This is now resolved,
and, to top the injury off, we have a backwards-compatible option for those
users who got used to the new name since 3.7. Ugh, sorry about that.
Other than that, some other minor fixes for issues that have been reported by
users.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull TTY/serial fixes from Greg Kroah-Hartman:
"Here are some tty/serial driver fixes for 3.9.
The big thing here is the fix for the huge mess we caused renaming the
8250 driver accidentally in the 3.7 kernel release, without realizing
that there were users of the module options that suddenly broke. This
is now resolved, and, to top the injury off, we have a backwards-
compatible option for those users who got used to the new name since
3.7. Ugh, sorry about that.
Other than that, some other minor fixes for issues that have been
reported by users."
* tag 'tty-3.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
Xilinx: ARM: UART: clear pending irqs before enabling irqs
TTY: 8250, deprecated 8250_core.* options
TTY: 8250, revert module name change
serial: 8250_pci: Add WCH CH352 quirk to avoid Xscale detection
tty: atmel_serial_probe(): index of atmel_ports[] fix
Consider a situation where I have an ARM based system
and therefore no legacy ports. Say, I have two
memory-mapped ports. I use device tree to describe the
ports. What would be the config options I set so that
I get only the two ports in my system? I do not want
legacy ports being created automatically and I want
it to be flexible enough that it creates the devices
based only on the device tree. I expected setting
SERIAL_8250_RUNTIME_UARTS = 0 to work because the
description said, "Set this to the maximum number of
serial ports you want the kernel to register at boot
time." Unfortunately, even though SERIAL_8250_NR_UARTS
was set to the default value of 4, I did not get any device
nodes (because SERIAL_8250_RUNTIME_UARTS was 0). This
is what this change is addressing.
SERIAL_8250_NR_UARTS controls the maximum number of ports
you can support. SERIAL_8250_RUNTIME_UARTS specifies the
number of ports you want to create automatically for legacy
ports at boot time. All other ports will be created
when serial8250_register_port is called (and if does not exceed
the total number of supported ports as specified by
SERIAL_8250_NR_UARTS).
Signed-off-by: Karthik Manamcheri <karthik.manamcheri@ni.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull vfs fixes from Al Viro:
"stable fodder; assorted deadlock fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vt: synchronize_rcu() under spinlock is not nice...
Nest rename_lock inside vfsmount_lock
Don't bother with redoing rw_verify_area() from default_file_splice_from()
vcs_poll_data_free() calls unregister_vt_notifier(), which calls
atomic_notifier_chain_unregister(), which calls synchronize_rcu().
Do it *after* we'd dropped ->f_lock.
Cc: stable@vger.kernel.org (all kernels since 2.6.37)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch series covers both ASoC and extcon subsystems and fixes an
interaction between the HPDET function and the headphone outputs - we
really shouldn't run HPDET while the headphone is active. The first
patch is a refactoring to make the extcon side easier.
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Merge tag 'arizona-extcon-asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc into char-misc-next
Mark writes:
ASoC/extcon: arizona: Fix interaction between HPDET and headphone outputs
This patch series covers both ASoC and extcon subsystems and fixes an
interaction between the HPDET function and the headphone outputs - we
really shouldn't run HPDET while the headphone is active. The first
patch is a refactoring to make the extcon side easier.
Support for the WindRiver SBC8560 board was removed in v3.6. But there
are still a few lines depending on its obsolete Kconfig macro. Remove
these now.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Automatic Flow Control capability is not tied to this
property. This is only one way of detecting it. The property
is limited to be used only with 8250 driver.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Boot ROM has an issue which will cause the driver to
lock up as pending irqs are not being cleared. With them
cleared it prevents that issue.
This patch is needed for the current (3.9-rc3) mainline kernel. I guess
it went unnoticed, because it was only tested with u-boot up until now.
And u-boot maybe handles this.
[s.trumtrar@pengutronix.de: cherry-picked from linux-xlnx.git]
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
They were introduced by mistake in 3.7. Let's deprecate them now. For
the reasons, see the text in Kconfig below.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In 3.7 the 8250 module name was changed unintentionally from 8250 to
8250_core by commit 835d844d1a
(8250_pnp: do pnp probe before legacy probe). We then had to
re-introduce the old module options to ensure the old good
8250.nr_uart & co. still work. This can be done only by a very dirty
hack and we did it in f2b8dfd9e4
(serial: 8250: Keep 8250.<xxxx> module options functional after driver
rename).
That is so damn ugly so that I decided to revert to the old module
name and deprecate the new 8250_core options present in 3.7 and 3.8
only. The deprecation will happen in the following patch.
Note that this patch changes the hack above to support "8250_core.*",
because we now have "8250.*" natively.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The datesheet clearly states, that writing low bits to the
XUARTPS_IDR register have no effect. Remove the write.
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Support for SH7367 and SH7377 got removed in v3.8. Now remove their
last Kconfig macros.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This will reduce the need for extra types in 8250.c just
in case the fifo size differs from the standard.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In most cases the tx_loadsz is the same as fifosize. This
will store the fifosize in it if it was not separately
delivered from the driver.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull sparc fixes from David Miller:
"Just some minor fixups, a sunsu console setup panic cure, and
recognition of a Fujitsu sun4v cpu."
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
sparc: remove unused "config BITS"
sparc: delete "if !ULTRA_HAS_POPULATION_COUNT"
sparc64: correctly recognize SPARC64-X chips
sparc,leon: fix GRPCI2 device0 PCI config space access
sunsu: Fix panic in case of nonexistent port at "console=ttySY" cmdline option
The following commits:
* 6732c8bb86 (TTY: switch
tty_schedule_flip)
* 2e124b4a39 (TTY: switch
tty_flip_buffer_push)
* 05c7cd3990 (TTY: switch
tty_insert_flip_string)
* 92a19f9cec (TTY: switch
tty_insert_flip_char)
* 227434f898 (TTY: switch
tty_buffer_request_room to tty_port)
introduced a potential NULL dereference to some drivers. In
particular, when the device is used as a console, incoming bytes can
kill the box. This is caused by removed checks for TTY against NULL.
It happened because it was unclear to me why the checks were there. I
assumed them superfluous because the interrupts were unbound or
otherwise stopped. But this is not the case for consoles for these
drivers, as was pointed out by David Miller.
Now, this patch re-introduces the checks (at this point we check
port->state, not the tty proper, as we do not care about tty pointers
anymore). For both of the drivers, we place the check below the
handling of break signal so that sysrq can actually work. (One needs
to issue a break and then sysrq key within the following 5 seconds.)
We do not change sc26xx, sunhv, and sunsu here because they behave the
same as before. People having that hardware should fix the driver
eventually, however. They always could unconditionally dereference tty
in receive_chars, port->state in uart_handle_dcd_change, and
up->port.state->port.tty.
There is perhaps more to fix in all those drivers, but they are at
least in a state they were before.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: sparclinux@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_perform_flush() can deadlock when called while holding
a line discipline reference. By definition, all ldisc drivers
hold a ldisc reference, so calls originating from ldisc drivers
must not block for a ldisc reference.
The deadlock can occur when:
CPU 0 | CPU 1
|
tty_ldisc_ref(tty) |
.... | <line discipline halted>
tty_ldisc_ref_wait(tty) |
|
CPU 0 cannot progess because it cannot obtain an ldisc reference
with the line discipline has been halted (thus no new references
are granted).
CPU 1 cannot progress because an outstanding ldisc reference
has not been released.
An in-tree call-tree audit of tty_perform_flush() [1] shows 5
ldisc drivers calling tty_perform_flush() indirectly via
n_tty_ioctl_helper() and 2 ldisc drivers calling directly.
A single tty driver safely uses the function.
[1]
Recursive usage:
/* These functions are line discipline ioctls and thus
* recursive wrt line discipline references */
tty_perform_flush() - ./drivers/tty/tty_ioctl.c
n_tty_ioctl_helper()
hci_uart_tty_ioctl(default) - drivers/bluetooth/hci_ldisc.c (N_HCI)
n_hdlc_tty_ioctl(default) - drivers/tty/n_hdlc.c (N_HDLC)
gsmld_ioctl(default) - drivers/tty/n_gsm.c (N_GSM0710)
n_tty_ioctl(default) - drivers/tty/n_tty.c (N_TTY)
gigaset_tty_ioctl(default) - drivers/isdn/gigaset/ser-gigaset.c (N_GIGASET_M101)
ppp_synctty_ioctl(TCFLSH) - drivers/net/ppp/pps_synctty.c
ppp_asynctty_ioctl(TCFLSH) - drivers/net/ppp/ppp_async.c
Non-recursive use:
tty_perform_flush() - drivers/tty/tty_ioctl.c
ipw_ioctl(TCFLSH) - drivers/tty/ipwireless/tty.c
/* This function is a tty i/o ioctl method, which
* is invoked by tty_ioctl() */
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that tty_ldisc_assign() is a one-line file-scoped function,
remove it and perform the simple assignment at its call sites.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge get_ldisc() into its only call site.
Note how, after merging, the unsafe acquire of an ldisc reference
is obvious.
CPU 0 in tty_ldisc_try() | CPU 1 in tty_ldisc_halt()
|
test_bit(TTY_LDISC, &tty_flags) |
if (true) | clear_bit(TTY_LDISC, &tty_flags)
tty->ldisc != 0? | atomic_read(&tty->ldisc->users)
if (true) | ret_val == 1?
atomic_inc(&tty->ldisc->users) | if (false)
| wait
|
<goes on assuming safe ldisc use> | <doesn't wait - proceeds w/ close>
|
The spin lock in tty_ldisc_try() does nothing wrt synchronizing
the ldisc halt since it's not acquired as part of halting.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_ldisc_ref()/tty_ldisc_unref() have usage semantics
equivalent to down_read_trylock()/up_read(). Only
callers of tty_ldisc_put() are performing the additional
operations necessary for proper ldisc teardown, and then only
after ensuring no outstanding 'read lock' remains.
Thus, tty_ldisc_unref() should never be the last reference;
WARN if it is. Conversely, tty_ldisc_put() should never be
destructing if the use count != 1.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
test_bit() is already atomic; drop mutex lock/unlock.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This comment is a victim of code migration from
"tty: Fix the ldisc hangup race"; re-parent it.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The tty core relies on the ldisc layer for synchronizing destruction
of the tty. Instead, the final tty release must wait for any pending tty
work to complete prior to tty destruction.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Waiting for buffer work to complete is not required for safely
performing changes to the line discipline, once the line discipline
is halted. The buffer work routine, flush_to_ldisc(), will be
unable to acquire an ldisc ref and all existing references were
waited until released (so it can't already have one).
Ensure running buffer work which may reference the soon-to-be-gone
tty completes and any buffer work running after this point retrieves
a NULL tty.
Also, ensure all buffer work is cancelled on port destruction.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_ldisc_hangup() guarantees the ldisc is enabled (or that there
is no ldisc). Since __tty_hangup() was the only user, re-define
tty_ldisc_enable() in file-scope.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver is no longer unthrottled on buffer reset, so remove
comments that claim it is.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SAK work may schedule hangup work (if TTY_SOFT_SAK is defined), thus
SAK work must be flushed before hangup work.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The pty driver does not obtain an ldisc reference to the linked
tty when writing. When the ldiscs are sequentially halted, it
is possible for one ldisc to be halted, and before the second
ldisc can be halted, a concurrent write schedules buffer work on
the first ldisc. This can lead to an access-after-free error when
the scheduled buffer work starts on the closed ldisc.
Prevent subsequent use after halt by performing each stage
of the halt on both ttys.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In preparation for destructing and freeing the tty, the line discipline
must first be brought to an inactive state before it can be destructed.
This line discipline shutdown must:
- disallow new users of the ldisc
- wait for existing ldisc users to finish
- only then, cancel/flush their pending/running work
Factor tty_ldisc_wait_idle() from tty_set_ldisc() and tty_ldisc_kill()
to ensure this shutdown order.
Failure to provide this guarantee can result in scheduled work
running after the tty has already been freed, as indicated in the
following log message:
[ 88.331234] WARNING: at drivers/tty/tty_buffer.c:435 flush_to_ldisc+0x194/0x1d0()
[ 88.334505] Hardware name: Bochs
[ 88.335618] tty is bad=-1
[ 88.335703] Modules linked in: netconsole configfs bnep rfcomm bluetooth ......
[ 88.345272] Pid: 39, comm: kworker/1:1 Tainted: G W 3.7.0-next-20121129+ttydebug-xeon #20121129+ttydebug
[ 88.347736] Call Trace:
[ 88.349024] [<ffffffff81058aff>] warn_slowpath_common+0x7f/0xc0
[ 88.350383] [<ffffffff81058bf6>] warn_slowpath_fmt+0x46/0x50
[ 88.351745] [<ffffffff81432bd4>] flush_to_ldisc+0x194/0x1d0
[ 88.353047] [<ffffffff816f7fe1>] ? _raw_spin_unlock_irq+0x21/0x50
[ 88.354190] [<ffffffff8108a809>] ? finish_task_switch+0x49/0xe0
[ 88.355436] [<ffffffff81077ad1>] process_one_work+0x121/0x490
[ 88.357674] [<ffffffff81432a40>] ? __tty_buffer_flush+0x90/0x90
[ 88.358954] [<ffffffff81078c84>] worker_thread+0x164/0x3e0
[ 88.360247] [<ffffffff81078b20>] ? manage_workers+0x120/0x120
[ 88.361282] [<ffffffff8107e230>] kthread+0xc0/0xd0
[ 88.362284] [<ffffffff816f0000>] ? cmos_do_probe+0x2eb/0x3bf
[ 88.363391] [<ffffffff8107e170>] ? flush_kthread_worker+0xb0/0xb0
[ 88.364797] [<ffffffff816fff6c>] ret_from_fork+0x7c/0xb0
[ 88.366087] [<ffffffff8107e170>] ? flush_kthread_worker+0xb0/0xb0
[ 88.367266] ---[ end trace 453a7c9f38fbfec0 ]---
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_ldisc_halt() will use the file-scoped function, tty_ldisc_wait_idle(),
in the following patch.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Flip buffer work cannot be cancelled until all outstanding ldisc
references have been released. Convert the ldisc ref wait into
a full ldisc halt with buffer work cancellation.
Note that the legacy mutex is not held while cancelling.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since the tty->ldisc is prevented from being changed by tty_set_ldisc()
when a tty is being hung up, re-testing the ldisc user count is
unnecessary -- ie, it cannot be a different ldisc and the user count
cannot have increased (assuming the caller meets the precondition that
TTY_LDISC flag is cleared)
Removal of the 'early-out' locking optimization is necessary for
the subsequent patch 'tty: Fix ldisc halt sequence on hangup'.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Refactor tty_ldisc_hangup() to extract standalone function,
tty_ldisc_hangup_wait_idle(), to wait for ldisc references
to be released.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Factor the packet mode status change from n_tty_flush_buffer
for use by follow-on patch.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Flip buffer work must not be scheduled by the line discipline
after the line discipline has been halted; issue warning.
Note: drivers can still schedule flip buffer work.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ifx6x60 driver implements both legacy suspend/resume callbacks and
dev_pm_ops. The SPI core is going to ignore legacy suspend/resume
callbacks if a driver implements dev_pm_ops. Since the legacy suspend/resume
callbacks are empty in this case it is safe to just remove them.
Cc: Bi Chao <chao.bi@intel.com>
Cc: Chen Jun <jun.d.chen@intel.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
mrst_max3110 driver.
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
max310x driver.
Cc: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
max3100 driver.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure we do not make tty-driver callbacks or wait for port to drain
on uninitialised ports (e.g. when open failed) in
tty_port_close_start().
No callback, such as flush_buffer or wait_until_sent, needs to be made
on a port that has never been opened. Neither does it make much sense to
add drain delay for an uninitialised port.
Currently a drain delay of up to two seconds could be added when a tty
fails to open.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move port drain-delay handling to a separate function.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move HUPCL handling to port shutdown so that DTR is dropped also on hang
up (tty_port_close is a noop for hung-up ports).
Also do not try to drop DTR for uninitialised ports where it has never
been raised (e.g. after a failed open).
Note that this is also the current behaviour of serial-core.
Nine drivers currently call tty_port_close_start directly (rather than
through tty_port_close) and seven of them lower DTR as part of their
close (if the port has been initialised). Fixup the remaining two
drivers so that it continues to be lowered also on normal (non-HUP)
close. [ Note that most of those other seven drivers did not expect DTR
to have been dropped by tty_port_close_start in the first place. ]
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure to check ASYNC_INITIALISED before raising DTR when waking up
from blocked open in tty_port_block_til_ready.
Currently DTR could get raised at hang up as a blocked process would
raise DTR unconditionally before checking for hang up and returning.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move wake up of processes on blocked-open and modem-status wait queues
to after port shutdown at hangup.
This way the woken up processes can use the ASYNC_INITIALIZED flag to
detect port shutdown.
Note that this is the order currently used by serial-core.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Untangle port-shutdown logic and make sure the initialised flag is
always cleared for non-console ports.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The same as flags, convert to using open/close counts from tty_port.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The same as flags, convert to using *_wait queues from tty_port.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The same as flags, convert to using close delays from tty_port.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Well, all those are unused. They were perhaps copied from generic
serial structure ages ago. Remove them for good.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The return value is not used anywhere, so no need to return anything.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
First, remove STD_FLAGS as the value, or its subvalues
(ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST) is not tested anywhere --
there is no point to initialize flags to that. Second, use flags
member from tty_port when we have it now. So that we do not waste
space.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty->hw_stopped is set only by drivers to remember HW state. If it is
never set to 1 in a particular driver, there is no need to check it in
the driver at all. Remove such checks.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are no (and never were any) kgdb fields in uart_ops. Setting
them produces a build error:
drivers/tty/serial/bfin_uart.c:1054:2: error: unknown field 'kgdboc_port_startup' specified in initializer
drivers/tty/serial/bfin_uart.c:1054:2: warning: initialization from incompatible pointer type [enabled by default]
drivers/tty/serial/bfin_uart.c:1054:2: warning: (near initialization for 'bfin_serial_pops.ioctl') [enabled by default]
drivers/tty/serial/bfin_uart.c:1055:2: error: unknown field 'kgdboc_port_shutdown' specified in initializer
drivers/tty/serial/bfin_uart.c:1055:2: warning: initialization from incompatible pointer type [enabled by default]
drivers/tty/serial/bfin_uart.c:1055:2: warning: (near initialization for 'bfin_serial_pops.poll_init') [enabled by default]
Remove them.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It allows for cleaning up on a considerable amount of places. They did
port_get, hangup, kref_put. Now the only thing needed is to call
tty_port_tty_hangup which does exactly that. And they can also decide
whether to consider CLOCAL or completely ignore that.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
