tty: implement read_iter

Now that the ldisc read() function takes kernel pointers, it's fairly
straightforward to make the tty file operations use .read_iter() instead
of .read().

That automaticall

tty: implement read_iter

Now that the ldisc read() function takes kernel pointers, it's fairly
straightforward to make the tty file operations use .read_iter() instead
of .read().

That automatically gives us vread() and friends, and also makes it
possible to do .splice_read() on ttys again.

Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
Reported-by: Oliver Giles <ohw.giles@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer

The tty line discipline .read() function was passed the final user
pointer destination as an argument, which doesn't match the '

tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer

The tty line discipline .read() function was passed the final user
pointer destination as an argument, which doesn't match the 'write()'
function, and makes it very inconvenient to do a splice method for
ttys.

This is a conversion to use a kernel buffer instead.

NOTE! It does this by passing the tty line discipline ->read() function
an additional "cookie" to fill in, and an offset into the cookie data.

The line discipline can fill in the cookie data with its own private
information, and then the reader will repeat the read until either the
cookie is cleared or it runs out of data.

The only real user of this is N_HDLC, which can use this to handle big
packets, even if the kernel buffer is smaller than the whole packet.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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Merge branch 'cpuidle-fix' into fixes

Merge drm/drm-next into drm-intel-gt-next

Backmerging to get a common base for merging topic branches between
drm-intel-next and drm-intel-gt-next.

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@l

Merge drm/drm-next into drm-intel-gt-next

Backmerging to get a common base for merging topic branches between
drm-intel-next and drm-intel-gt-next.

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

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Merge drm/drm-next into drm-intel-next

sync-up to not fall too much behind.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Merge branch 'kvm-master' into kvm-next

Fixes to get_mmio_spte, destined to 5.10 stable branch.

Merge branch 'for-linus' into for-next

Back-merge of 5.11-devel branch for syncing the result changes.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

Merge tag 'asoc-fix-v5.11-rc2' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v5.11

A collection of mostly driver specific fixes, plus a maintainers

Merge tag 'asoc-fix-v5.11-rc2' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v5.11

A collection of mostly driver specific fixes, plus a maintainership
update for TI and a fix for DAPM driver removal paths.

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drivers:tty:pty: Fix a race causing data loss on close

Remove the tty_vhangup() from the pty code and just release the
redirect. The tty_vhangup() results in data loss and data out of order
issues.

drivers:tty:pty: Fix a race causing data loss on close

Remove the tty_vhangup() from the pty code and just release the
redirect. The tty_vhangup() results in data loss and data out of order
issues.

If you write to a pty master an immediately close the pty master, the
receiver might get a chunk of data dropped, but then receive some later
data. That's obviously something rather unexpected for a user. It
certainly confused my test program.

It turns out that tty_vhangup() on the slave pty gets called from
pty_close(), and that causes the data on the slave side to be flushed,
but due to races more data can be copied into the slave side's buffer
after that. Consider the following sequence:

thread1 thread2 thread3
------- ------- -------
| |-write data into buffer,
| | n_tty buffer is filled
| | along with other buffers
| |-pty_close(master)
| |--tty_vhangup(slave)
| |---tty_ldisc_hangup()
| |----n_tty_flush_buffer()
| |-----reset_buffer_flags()
|-n_tty_read() |
|--up_read(&tty->termios_rwsem);
| |------down_read(&tty->termios_rwsem)
| |------clear n_tty buffer contents
| |------up_read(&tty->termios_rwsem)
|--tty_buffer_flush_work() |
|--schedules work calling |
| flush_to_ldisc() |
| |-flush_to_ldisc()
| |--receive_buf()
| |---tty_port_default_receive_buf()
| |----tty_ldisc_receive_buf()
| |-----n_tty_receive_buf2()
| |------n_tty_receive_buf_common()
| |-------down_read(&tty->termios_rwsem)
| |-------__receive_buf()
| | copies data into n_tty buffer
| |-------up_read(&tty->termios_rwsem)
|--down_read(&tty->termios_rwsem)
|--copy buffer data to user

>From this sequence, you can see that thread2 writes to the buffer then
only clears the part of the buffer in n_tty. The n_tty receive buffer
code then copies more data into the n_tty buffer.

But part of the vhangup, releasing the redirect, is still required to
avoid issues with consoles running on pty slaves. So do that.
As far as I can tell, that is all that should be required.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/20201124004902.1398477-3-minyard@acm.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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tty: Export redirect release

This will be required by the pty code when it removes tty_vhangup() on
master close.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/

tty: Export redirect release

This will be required by the pty code when it removes tty_vhangup() on
master close.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/20201124004902.1398477-2-minyard@acm.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge drm/drm-next into drm-misc-next

Staying in sync to drm-next, and to be able to pull ttm fixes.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

tty: new helper function tty_get_icount()

For a given struct tty_struct this yields the corresponding statistics
about sent and received characters (and some more) which is needed to
implement an LE

tty: new helper function tty_get_icount()

For a given struct tty_struct this yields the corresponding statistics
about sent and received characters (and some more) which is needed to
implement an LED trigger for tty devices.

The new function is then used to simplify tty_tiocgicount().

Reviewed-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20201218104246.591315-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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tty: rename tty_kopen() and add new function tty_kopen_shared()

Introduce a new function tty_kopen_shared() that yields a struct
tty_struct. The semantic difference to tty_kopen() is that the tty is

tty: rename tty_kopen() and add new function tty_kopen_shared()

Introduce a new function tty_kopen_shared() that yields a struct
tty_struct. The semantic difference to tty_kopen() is that the tty is
expected to be used already. So rename tty_kopen() to
tty_kopen_exclusive() for clearness, adapt the single user and put the
common code in a new static helper function.

tty_kopen_shared is to be used to implement an LED trigger for tty
devices in one of the next patches.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20201218104246.591315-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge tag 'v5.11-rc1' into spi-5.11

Linux 5.11-rc1

Merge tag 'v5.11-rc1' into regulator-5.11

Linux 5.11-rc1

Merge tag 'v5.11-rc1' into asoc-5.11

Linux 5.11-rc1

Merge branch 'fixes-omap3' into fixes

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes and check what UAPI headers need to be synched.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Merge tags 'spi-nor/for-5.11' and 'nand/for-5.11' into mtd/next

SPI NOR core changes:

- Initial support for stateful Octal DTR mode using volatile settings
- Preliminary support for JEDEC 251 (xSPI

Merge tags 'spi-nor/for-5.11' and 'nand/for-5.11' into mtd/next

SPI NOR core changes:

- Initial support for stateful Octal DTR mode using volatile settings
- Preliminary support for JEDEC 251 (xSPI) and JEDEC 216D standards
- Support for Cypress Semper flash
- Support to specify ECC block size of SPI NOR flashes
- Fixes to avoid clearing of non-volatile Block Protection bits at probe

Generic NAND core:
* ECC management:
- Add an I/O request tweaking mechanism
- Entire rework of the software BCH ECC driver, creation of a real
ECC engine, getting rid of raw NAND structures, migration to more
generic prototypes, misc fixes and style cleanup. Moved now to the
Generic NAND layer.
- Entire rework of the software Hamming ECC driver, creation of a
real ECC engine, getting rid of raw NAND structures, misc renames,
comment updates, cleanup, and style fixes. Moved now to the
generic NAND layer.
- Necessary plumbing at the NAND level to retrieve generic NAND ECC
engines (softwares and on-die).
- Update of the bindings.

Raw NAND core:
* Geting rid of the chip->ecc.priv entry.
* Fix miscellaneous typos in kernel-doc

Raw NAND controller drivers:
* AU1550: Ensure the presence of the right includes
* Davinci: Do not use extra dereferencing
* GPMI:
- Fix the driver only sense CS0 R/B issue
- Fix the random DMA timeout issue
- Use a single line for of_device_id
- Use of_device_get_match_data()
- Fix reference count leak in gpmi ops
- Cleanup makefile
- Fix binding matching of clocks on different SoCs
* Ingenic: remove redundant get_device() in ingenic_ecc_get()
* Intel LGM: New NAND controller driver
* Marvell: Drop useless line
* Meson:
- Fix a resource leak in init
- Fix meson_nfc_dma_buffer_release() arguments
* mxc:
- Use device_get_match_data()
- Use a single line for of_device_id
- Remove platform data support
* Qcom:
- Add support for SDX55
- Support for IPQ6018 QPIC NAND controller
- Fix DMA sync on FLASH_STATUS register read
* Rockchip: New NAND controller driver for RK3308, RK2928 and others
* Sunxi: Add MDMA support

SPI-NAND core:
* Creation of a SPI-NAND on-die ECC engine
* Move ECC related definitions earlier in the driver
* Fix typo in comment
* Fill a default ECC provider/algorithm
* Remove outdated comment
* Fix OOB read
* Allow the case where there is no ECC engine
* Use the external ECC engine logic

SPI-NAND chip drivers:
* Micron:
- Add support for MT29F2G01AAAED
- Use more specific names
* Macronix:
- Add support for MX35LFxG24AD
- Add support for MX35LFxGE4AD

Others:
* onenand: Use mtd->oops_panic_write as condition
* plat-ram: correctly free memory on error path in platram_probe()

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Merge branch 'for-5.11/elecom' into for-linus

- support for EX-G M-XGL20DLBK device, from YOSHIOKA Takuma

Merge tag 'tty-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial updates from Greg KH:
"Here is the "large" set of tty and serial patches for 5.11-rc1.

Noth

Merge tag 'tty-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial updates from Greg KH:
"Here is the "large" set of tty and serial patches for 5.11-rc1.

Nothing major at all, some cleanups and some driver removals, always a
nice sign:

- build warning cleanups

- vt locking and logic unwinding and cleanups

- tiny serial driver fixes and updates

- removal of the synclink serial driver as it's no longer needed

- removal of dead termiox code

All of this has been in linux-next for a while with no reported issues"

* tag 'tty-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (89 commits)
serial: 8250_pci: Drop bogus __refdata annotation
tty: serial: meson: enable console as module
serial: 8250_omap: Avoid FIFO corruption caused by MDR1 access
serial: imx: Move imx_uart_probe_dt() content into probe()
serial: imx: Remove unneeded of_device_get_match_data() NULL check
tty: Fix whitespace inconsistencies in vt_io_ioctl
serial_core: Check for port state when tty is in error state
dt-bindings: serial: Update DT binding docs to support SiFive FU740 SoC
tty: use const parameters in port-flag accessors
tty: use assign_bit() in port-flag accessors
earlycon: drop semicolon from earlycon macro
tty: Remove dead termiox code
tty/serial/imx: Enable TXEN bit in imx_poll_init().
tty : serial: jsm: Fixed file by adding spacing
tty: serial: uartlite: Support probe deferral
earlycon: simplify earlycon-table implementation
tty: serial: bcm63xx: lower driver dependencies
serial: mxs-auart: Remove unneeded platform_device_id
serial: 8250-mtk: Fix reference leak in mtk8250_probe
serial: imx: Remove unused .id_table support
...

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Merge drm/drm-next into drm-misc-next

Required backmerge since we will be based on top of v5.11, and there
has been a request to backmerge already to upstream some features.

Signed-off-by: Maarten

Merge drm/drm-next into drm-misc-next

Required backmerge since we will be based on top of v5.11, and there
has been a request to backmerge already to upstream some features.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

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Merge tag 'irqchip-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core

Pull irqchip updates for 5.11 from Marc Zyngier:

- Preliminary support for managed interr

Merge tag 'irqchip-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core

Pull irqchip updates for 5.11 from Marc Zyngier:

- Preliminary support for managed interrupts on platform devices
- Correctly identify allocation of MSIs proxyied by another device
- Remove the fasteoi IPI flow which has been proved useless
- Generalise the Ocelot support to new SoCs
- Improve GICv4.1 vcpu entry, matching the corresponding KVM optimisation
- Work around spurious interrupts on Qualcomm PDC
- Random fixes and cleanups

Link: https://lore.kernel.org/r/20201212135626.1479884-1-maz@kernel.org

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Merge branch 'next' into for-linus

Prepare input updates for 5.11 merge window.

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

xdp_return_frame_bulk() needs to pass a xdp_buff
to __xdp_return().

strlcpy got converted to strscpy but here it makes no
functional d

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

xdp_return_frame_bulk() needs to pass a xdp_buff
to __xdp_return().

strlcpy got converted to strscpy but here it makes no
functional difference, so just keep the right code.

Conflicts:
net/netfilter/nf_tables_api.c

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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