serial: 8250_bcm7271: Fix error handling in brcmuart_init()

A problem about 8250_bcm7271 create debugfs failed is triggered with the
following log given:

 [  324.516635] debugfs: Directory 'bcm7271-uart' with parent '/' already present!

The reason is that brcmuart_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without destroy the newly created debugfs, resulting
the debugfs of 8250_bcm7271 can never be created later.

 brcmuart_init()
   debugfs_create_dir() # create debugfs directory
   platform_driver_register()
     driver_register()
       bus_add_driver()
         priv = kzalloc(...) # OOM happened
   # return without destroy debugfs directory

Fix by removing debugfs when platform_driver_register() returns error.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Link: https://lore.kernel.org/r/20221109072110.117291-2-yuancan@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_dma: Rearm DMA Rx if more data is pending

When DMA Rx completes, the current behavior is to just exit the DMA
completion handler without future actions. If the transfer is still
on-going, UART will trigger an interrupt and that eventually rearms the
DMA Rx. The extra interrupt round-trip has an inherent latency cost
that increases the risk of FIFO overrun. In such situations, the
latency margin tends to already be less due to FIFO not being empty.

Add check into DMA Rx completion handler to detect if LSR has DR (Data
Ready) still set. DR indicates there will be more characters pending
and DMA Rx can be rearmed right away to handle them.

Cc: Gilles BULOZ <gilles.buloz@kontron.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221107102126.56481-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: Fix a typo ("ignorning")

Fix the two instances of this typo present in the MSM and VT8500 serial
drivers.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Acked-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20221104103719.2234098-1-j.neuschaefer@gmx.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: Convert tty_buffer flags to bool

The struct tty_buffer has flags which is only used for storing TTYB_NORMAL.
There is also a few quite confusing operations for checking the presense
of TTYB_NORMAL. Simplify things by converting flags to bool.

Despite the name remaining the same, the meaning of "flags" is altered
slightly by this change. Previously it referred to flags of the buffer
(only TTYB_NORMAL being used as a flag). After this change, flags tell
whether the buffer contains/should be allocated with flags array along
with character data array. It is much more suitable name that
TTYB_NORMAL was for this purpose, thus the name remains.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019105504.16800-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: Move TIOCSTI toggle variable before kerndoc

The variable "tty_legacy_tiocsti" should be defined before the kerndoc
for the tiocsti() function. The new variable was breaking the "htmldocs"
build target:

drivers/tty/tty_io.c:2271: warning: cannot understand function prototype: 'bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI); '

Fixes: 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/lkml/20221107143434.66f7be35@canb.auug.org.au
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20221107034631.never.637-kees@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: Cleanup tty buffer align mask

Don't use decimal for mask. Don't use literal for aligning.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019105504.16800-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

dt-bindings: serial: renesas,scif: Document r8a779g0 support

Document support for the Serial Communication Interface with FIFO (SCIF)
in the Renesas R-Car V4H (R8A779G0) SoC.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/8a2d04651f04a97d652395b4d933af5c3c8d5b5b.1666360789.git.geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: hvc: make hvc_rtas_dev static

The symbol is not used outside of the file, so mark it static.

Fixes the following warning:

drivers/tty/hvc/hvc_rtas.c:29:19: warning: symbol 'hvc_rtas_dev' was
not declared. Should it be static?

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20221019064412.3759874-1-ruanjinjie@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_core: Use str_enabled_disabled() helper

Use str_enabled_disabled() helper instead of open coding the same.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221017171633.65275-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: imx: Handle RS485 DE signal active high

The default polarity of RS485 DE signal is active high. This driver does
not handle such case properly. Currently, when a pin is multiplexed as a
UART CTS_B on boot, this pin is pulled HIGH by the i.MX UART CTS circuit,
which activates DE signal on the RS485 transceiver and thus behave as if
the RS485 was transmitting data, so the system blocks the RS485 bus when
it starts and until user application takes over. This behavior is not OK.
The problem consists of two separate parts.

First, the i.MX UART IP requires UCR1 UARTEN and UCR2 RXEN to be set for
UCR2 CTSC and CTS bits to have any effect. The UCR2 CTSC bit permits the
driver to set CTS (RTS_B or RS485 DE signal) to either level sychronous
to the internal UART IP clock. Compared to other options, like GPIO CTS
control, this has the benefit of being synchronous to the UART IP clock
and thus without glitches or bus delays. The reason for the CTS design
is likely because when the Receiver is disabled, the UART IP can never
indicate that it is ready to receive data by assering CTS signal, so
the CTS is always pulled HIGH by default.

When the port is closed by user space, imx_uart_stop_rx() clears UCR2
RXEN bit, and imx_uart_shutdown() clears UCR1 UARTEN bit. This disables
UART Receiver and UART itself, and forces CTS signal HIGH, which leads
to the RS485 bus being blocked because RS485 DE is incorrectly active.

The proposed solution for this problem is to keep the Receiver running
even after the port is closed, but in loopback mode. This disconnects
the RX FIFO input from the RXD external signal, and since UCR2 TXEN is
cleared, the UART Transmitter is disabled, so nothing can feed data in
the RX FIFO. Because the Receiver is still enabled, the UCR2 CTSC and
CTS bits still have effect and the CTS (RS485 DE) control is retained.

Note that in case of RS485 DE signal active low, there is no problem and
no special handling is necessary. The CTS signal defaults to HIGH, thus
the RS485 is by default set to Receive and the bus is not blocked.

Note that while there is the possibility to control CTS using GPIO with
either CTS polarity, this has the downside of not being synchronous to
the UART IP clock and thus glitchy and susceptible to slow DE switching.

Second, on boot, before the UART driver probe callback is called, the
driver core triggers pinctrl_init_done() and configures the IOMUXC to
default state. At this point, UCR1 UARTEN and UCR2 RXEN are both still
cleared, but UART CTS_B (RS485 DE) is configured as CTS function, thus
the RTS signal is pulled HIGH by the UART IP CTS circuit.

One part of the solution here is to enable UCR1 UARTEN and UCR2 RXEN and
UTS loopback in this driver probe callback, thus unblocking the CTSC and
CTS control early on. But this is still too late, since the pin control
is already configured and CTS has been pulled HIGH for a short period
of time.

When Linux kernel boots and this driver is bound, the pin control is set
to special "init" state if the state is available, and driver can switch
the "default" state afterward when ready. This state can be used to set
the CTS line as a GPIO in DT temporarily, and a GPIO hog can force such
GPIO to LOW, thus keeping the RS485 DE line LOW early on boot. Once the
driver takes over and UCR1 UARTEN and UCR2 RXEN and UTS loopback are all
enabled, the driver can switch to "default" pin control state and control
the CTS line as function instead. DT binding example is below:

"
&gpio6 {
  rts-init-hog {
    gpio-hog;
    gpios = <5 0>;
    output-low;
    line-name = "rs485-de";
  };
};

&uart5 { /* DHCOM UART2 */
  pinctrl-0 = <&pinctrl_uart5>;
  pinctrl-1 = <&pinctrl_uart5_init>;
  pinctrl-names = "default", "init";
  ...
};
pinctrl_uart5_init: uart5-init-grp {
  fsl,pins = <
...
    MX6QDL_PAD_CSI0_DAT19__GPIO6_IO05       0x30b1
  >;
};

pinctrl_uart5: uart5-grp {
  fsl,pins = <
...
    MX6QDL_PAD_CSI0_DAT19__UART5_CTS_B      0x30b1
  >;
};
"

Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20220929144400.13571-1-marex@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250/ingenic: Add support for the JZ4750/JZ4755

JZ4750/55/60 (but not JZ4760b) have an optional /2 divider between the
EXT oscillator and some peripherals including UART, which will
be enabled if using a 24 MHz oscillator, and disabled when
using a 12 MHz oscillator.

This behavior relies on hardware differences: most boards (if not all)
with those SoCs have 12 or 24 MHz oscillators but many peripherals want
12Mhz to operate properly (AIC and USB-PHY at least).

The 16MHz threshold looks arbitrary but used in vendor's bootloader code
for enable the divider.

The patch doesn't affect JZ4760's behavior as it is subject for another
patchset with re-classification of all supported ingenic UARTs.

Link: https://github.com/carlos-wong/uboot_jz4755/blob/master/cpu/mips/jz_serial.c#L158
Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221031184041.1338129-3-lis8215@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

dt-bindings: serial: ingenic: Add support for the JZ4750/55 SoCs

These SoCs UART block are the same as JZ4725b' one, the difference is
outside of the block - it is in the clock generation unit (CGU).
The difference requires to make a quirk for early console init.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221031184041.1338129-2-lis8215@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation: Make formatting consistent for rs485 docs

Tweak styling of names that come directly from the code.

Suggested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation: rs485: Fix struct referencing

Use "struct serial_rs485" to get the references properly recognized.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation: rs485: Mention uart_get_rs485_mode()

Add to rs485 documentation that serial core prepares the struct
serial_rs485 when uart_get_rs485_mode() is called. Remove the wrong
claim that the driver must fill it by itself.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation: rs485: Link reference properly

Link DT bindings reference properly.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: Convert serial_rs485 to kernel doc

Convert struct serial_rs485 comments to kernel doc format and include
it into documentation.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: tegra: Read DMA status before terminating

Read the DMA status before terminating the DMA, as doing so deletes
the DMA desc.

Also, to get the correct transfer status information, pause the DMA
using dmaengine_pause() before reading the DMA status.

Fixes: e9ea096dd225 ("serial: tegra: add serial driver")
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
Link: https://lore.kernel.org/r/1666105086-17326-1-git-send-email-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: zs: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-45-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: xuartps: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-44-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: ucc_uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-43-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: uartlite: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-42-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: timbuart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-41-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sunzilog: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-40-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sunsu: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-39-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sunsab: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-38-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sunplus-uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-37-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sunhv: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-36-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: stm32: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-35-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sprd: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-34-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sh-sci: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-33-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: tegra: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-32-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sccnxp: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-31-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sb1250-duart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-30-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: samsung_tty: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-29-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: rda: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-28-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: pmac_zilog: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-27-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: pic32: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-26-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: mvebu-uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-25-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: milbeaut_usio: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-24-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: meson: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-23-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: max310x: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-22-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: max3100: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-21-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: liteuart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Acked-by: Gabriel Somlo <gsomlo@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-20-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: ip22zilog: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-19-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: imx: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-18-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: fsl_lpuart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-17-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: linflexuart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-16-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: digicolor: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Acked-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-15-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: cpm_uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-14-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: clps711x: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-13-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: atmel: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-By: Richard GENOUD <richard.genoud@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-12-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: arc: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-11-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: ar933x: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-10-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: pl011: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250_bcm7271: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sc16is7xx: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: pch_uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: msm: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: men_z135_uart: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: dz: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: 8250: 8250_omap: Support native RS485

Recent TI Sitara SoCs such as AM64/AM65 have gained the ability to
automatically assert RTS when data is transmitted, obviating the need
to emulate this functionality in software.

The feature is controlled through new DIR_EN and DIR_POL bits in the
Mode Definition Register 3.  For details see page 8783 and 8890 of the
AM65 TRM:  https://www.ti.com/lit/ug/spruid7e/spruid7e.pdf

Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Su Bao Cheng <baocheng.su@siemens.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Bin Liu <b-liu@ti.com>
Tested-by: Zeng Chao <chao.zeng@siemens.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/e9f25f5c9200a35d3162973c2b45d6b892cc9bf2.1665906869.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: qcom-geni-serial: Add support for Hibernation feature

Added changes to support the hibernation feature for serial UART.
Added support for freeze, restore and thaw callbacks to put the
device into hibernation.

Signed-off-by: Aniket Randive <quic_arandive@quicinc.com>
Link: https://lore.kernel.org/r/1665123780-20557-1-git-send-email-quic_arandive@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: use uart_port_tx_limited()

uart_port_tx_limited() is a new helper to send characters to the device.
Use it in these drivers.

mux.c also needs to define tx_done(). But I'm not sure if the driver
really wants to wait for all the characters to dismiss from the HW fifo
at this code point. Hence I marked this as FIXME.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "Pali Rohár" <pali@kernel.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: linux-riscv@lists.infradead.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221004104927.14361-4-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: use uart_port_tx() helper

uart_port_tx() is a new helper to send characters to the device. Use it
in these drivers.

Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221004104927.14361-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: serial: introduce transmit helpers

Many serial drivers do the same thing:
* send x_char if set
* keep sending from the xmit circular buffer until either
  - the loop reaches the end of the xmit buffer
  - TX is stopped
  - HW fifo is full
* check for pending characters and:
  - wake up tty writers to fill for more data into xmit buffer
  - stop TX if there is nothing in the xmit buffer

The only differences are:
* how to write the character to the HW fifo
* the check of the end condition:
  - is the HW fifo full?
  - is limit of the written characters reached?

So unify the above into two helpers:
* uart_port_tx_limited() -- it performs the above taking the written
  characters limit into account, and
* uart_port_tx() -- the same as above, except it only checks the HW
  readiness, not the characters limit.

The HW specific operations (as stated as "differences" above) are passed
as arguments to the macros. They are:
* tx_ready -- returns true if HW can accept more data.
* put_char -- write a character to the device.
* tx_done -- when the write loop is done, perform arbitrary action
  before potential invocation of ops->stop_tx() happens.

Note that the above are macros. This means the code is generated in
place and the above 3 arguments are "inlined". I.e. no added penalty by
generating call instructions for every single character. Nor any
indirect calls. (As in some previous versions of this patchset.)

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221004104927.14361-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: Allow TIOCSTI to be disabled

TIOCSTI continues its long history of being used in privilege escalation
attacks[1]. Prior attempts to provide a mechanism to disable this have
devolved into discussions around creating full-blown LSMs to provide
arbitrary ioctl filtering, which is hugely over-engineered -- only
TIOCSTI is being used this way. 3 years ago OpenBSD entirely removed
TIOCSTI[2], Android has had it filtered for longer[3], and the tools that
had historically used TIOCSTI either do not need it, are not commonly
built with it, or have had its use removed.

Provide a simple CONFIG and global sysctl to disable this for the system
builders who have wanted this functionality for literally decades now,
much like the ldisc_autoload CONFIG and sysctl.

[1] https://lore.kernel.org/linux-hardening/Y0m9l52AKmw6Yxi1@hostpad
[2] https://undeadly.org/cgi?action=article;sid=20170701132619
[3] https://lore.kernel.org/lkml/CAFJ0LnFGRuEEn1tCLhoki8ZyWrKfktbF+rwwN7WzyC_kBFoQVA@mail.gmail.com/

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Simon Brand <simon.brand@postadigitale.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221022182949.2684794-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: Move sysctl setup into "core" tty logic

In preparation for adding another sysctl to the tty subsystem, move the
tty setup code into the "core" tty code, which contains tty_init() itself.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221022182949.2684794-1-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: evh_bytechan: Replace NO_IRQ by 0

NO_IRQ is used to check the return of irq_of_parse_and_map().

On some architecture NO_IRQ is 0, on other architectures it is -1.

irq_of_parse_and_map() returns 0 on error, independent of NO_IRQ.

So use 0 instead of using NO_IRQ.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Acked-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/23f608ca57e7e19bc7060d3e563de383e0b2b337.1665033575.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sifive: select by default if SOC_CANAAN

With the aim of dropping direct selects of drivers from Kconfig.socs,
default the SiFive serial drivers to enabled if SOC_CANAAN.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221005171348.167476-4-conor@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

serial: sifive: select by default if SOC_SIFIVE

With the aim of dropping direct selects of drivers from Kconfig.socs,
default the SiFive serial drivers to the value of SOC_SIFIVE.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221005171348.167476-3-conor@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Linux 6.1-rc3

Merge tag 'fbdev-for-6.1-rc3' of git://git./linux/kernel/git/deller/linux-fbdev

Pull fbdev fixes from Helge Deller:
 "A use-after-free bugfix in the smscufx driver and various minor error
  path fixes, smaller build fixes, sysfs fixes and typos in comments in
  the stifb, sisfb, da8xxfb, xilinxfb, sm501fb, gbefb and cyber2000fb
  drivers"

* tag 'fbdev-for-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev:
  fbdev: cyber2000fb: fix missing pci_disable_device()
  fbdev: sisfb: use explicitly signed char
  fbdev: smscufx: Fix several use-after-free bugs
  fbdev: xilinxfb: Make xilinxfb_release() return void
  fbdev: sisfb: fix repeated word in comment
  fbdev: gbefb: Convert sysfs snprintf to sysfs_emit
  fbdev: sm501fb: Convert sysfs snprintf to sysfs_emit
  fbdev: stifb: Fall back to cfb_fillrect() on 32-bit HCRX cards
  fbdev: da8xx-fb: Fix error handling in .remove()
  fbdev: MIPS supports iomem addresses

Merge tag 'char-misc-6.1-rc3' of git://git./linux/kernel/git/gregkh/char-misc

Pull char/misc fixes from Greg KH:
 "Some small driver fixes for 6.1-rc3.  They include:

   - iio driver bugfixes

   - counter driver bugfixes

   - coresight bugfixes, including a revert and then a second fix to get
     it right.

  All of these have been in linux-next with no reported problems"

* tag 'char-misc-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (21 commits)
  misc: sgi-gru: use explicitly signed char
  coresight: cti: Fix hang in cti_disable_hw()
  Revert "coresight: cti: Fix hang in cti_disable_hw()"
  counter: 104-quad-8: Fix race getting function mode and direction
  counter: microchip-tcb-capture: Handle Signal1 read and Synapse
  coresight: cti: Fix hang in cti_disable_hw()
  coresight: Fix possible deadlock with lock dependency
  counter: ti-ecap-capture: fix IS_ERR() vs NULL check
  counter: Reduce DEFINE_COUNTER_ARRAY_POLARITY() to defining counter_array
  iio: bmc150-accel-core: Fix unsafe buffer attributes
  iio: adxl367: Fix unsafe buffer attributes
  iio: adxl372: Fix unsafe buffer attributes
  iio: at91-sama5d2_adc: Fix unsafe buffer attributes
  iio: temperature: ltc2983: allocate iio channels once
  tools: iio: iio_utils: fix digit calculation
  iio: adc: stm32-adc: fix channel sampling time init
  iio: adc: mcp3911: mask out device ID in debug prints
  iio: adc: mcp3911: use correct id bits
  iio: adc: mcp3911: return proper error code on failure to allocate trigger
  iio: adc: mcp3911: fix sizeof() vs ARRAY_SIZE() bug
  ...

Merge tag 'usb-6.1-rc3' of git://git./linux/kernel/git/gregkh/usb

Pull USB fixes from Greg KH:
 "A few small USB fixes for 6.1-rc3. Include in here are:

   - MAINTAINERS update, including a big one for the USB gadget
     subsystem. Many thanks to Felipe for all of the years of hard work
     he has done on this codebase, it was greatly appreciated.

   - dwc3 driver fixes for reported problems.

   - xhci driver fixes for reported problems.

   - typec driver fixes for minor issues

   - uvc gadget driver change, and then revert as it wasn't relevant for
     6.1-final, as it is a new feature and people are still reviewing
     and modifying it.

  All of these have been in the linux-next tree with no reported issues"

* tag 'usb-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: dwc3: gadget: Don't set IMI for no_interrupt
  usb: dwc3: gadget: Stop processing more requests on IMI
  Revert "usb: gadget: uvc: limit isoc_sg to super speed gadgets"
  xhci: Remove device endpoints from bandwidth list when freeing the device
  xhci-pci: Set runtime PM as default policy on all xHC 1.2 or later devices
  xhci: Add quirk to reset host back to default state at shutdown
  usb: xhci: add XHCI_SPURIOUS_SUCCESS to ASM1042 despite being a V0.96 controller
  usb: dwc3: st: Rely on child's compatible instead of name
  usb: gadget: uvc: limit isoc_sg to super speed gadgets
  usb: bdc: change state when port disconnected
  usb: typec: ucsi: acpi: Implement resume callback
  usb: typec: ucsi: Check the connection on resume
  usb: gadget: aspeed: Fix probe regression
  usb: gadget: uvc: fix sg handling during video encode
  usb: gadget: uvc: fix sg handling in error case
  usb: gadget: uvc: fix dropped frame after missed isoc
  usb: dwc3: gadget: Don't delay End Transfer on delayed_status
  usb: dwc3: Don't switch OTG -> peripheral if extcon is present
  MAINTAINERS: Update maintainers for broadcom USB
  MAINTAINERS: move USB gadget and phy entries under the main USB entry

Merge tag 'gpio-fixes-for-v6.1-rc3' of git://git./linux/kernel/git/brgl/linux

Pull gpio fixes from Bartosz Golaszewski:

 - convert gpio-tegra to using an immutable irqchip

 - MAINTAINERS update

* tag 'gpio-fixes-for-v6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  MAINTAINERS: Change myself to a maintainer
  gpio: tegra: Convert to immutable irq chip

Merge tag 'perf_urgent_for_v6.1_rc3' of git://git./linux/kernel/git/tip/tip

Pull perf fixes from Borislav Petkov:

 - Rename a perf memory level event define to denote it is of CXL type

 - Add Alder and Raptor Lakes support to RAPL

 - Make sure raw sample data is output with tracepoints

* tag 'perf_urgent_for_v6.1_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/mem: Rename PERF_MEM_LVLNUM_EXTN_MEM to PERF_MEM_LVLNUM_CXL
  perf/x86/rapl: Add support for Intel Raptor Lake
  perf/x86/rapl: Add support for Intel AlderLake-N
  perf: Fix missing raw data on tracepoint events

Merge tag 'loongarch-fixes-6.1-1' of git://git./linux/kernel/git/chenhuacai/linux-loongson

Pull LoongArch fixes from Huacai Chen:
 "Remove unused kernel stack padding, fix some build errors/warnings and
  two bugs in laptop platform driver"

* tag 'loongarch-fixes-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
  platform/loongarch: laptop: Fix possible UAF and simplify generic_acpi_laptop_init()
  platform/loongarch: laptop: Adjust resume order for loongson_hotkey_resume()
  LoongArch: BPF: Avoid declare variables in switch-case
  LoongArch: Use flexible-array member instead of zero-length array
  LoongArch: Remove unused kernel stack padding

Merge tag '6.1-rc2-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:

 - use after free fix for reconnect race

 - two memory leak fixes

* tag '6.1-rc2-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: fix use-after-free caused by invalid pointer `hostname`
  cifs: Fix pages leak when writedata alloc failed in cifs_write_from_iter()
  cifs: Fix pages array leak when writedata alloc failed in cifs_writedata_alloc()

Merge tag 'random-6.1-rc3-for-linus' of git://git./linux/kernel/git/crng/random

Pull random number generator fix from Jason Donenfeld:
 "One fix from Jean-Philippe Brucker, addressing a regression in which
  early boot code on ARM64 would use the non-_early variant of the
  arch_get_random family of functions, resulting in the architectural
  random number generator appearing unavailable during that early phase
  of boot.

  The fix simply changes arch_get_random*() to arch_get_random*_early().

  This distinction between these two functions is a bit of an old wart
  I'm not a fan of, and for 6.2 I'll see if I can make obsolete the
  _early variant, so that one function does the right thing in all
  contexts without overhead"

* tag 'random-6.1-rc3-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  random: use arch_get_random*_early() in random_init()

Merge tag 'scsi-fixes' of git://git./linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "Varions small  fixes, all  in drivers.

  Some of these arrived during the merge window and got held over to
  make sure of testing on the -rc tree.

  The biggest change is for standards conformance in the target driver,
  closely followed by a set of bug fixes in megaraid_sas"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (21 commits)
  scsi: ufs: core: Fix typo in comment
  scsi: mpi3mr: Select CONFIG_SCSI_SAS_ATTRS
  scsi: ufs: core: Fix typo for register name in comments
  scsi: pm80xx: Display proc_name in sysfs
  scsi: ufs: core: Fix the error log in ufshcd_query_flag_retry()
  scsi: ufs: core: Remove unneeded casts from void *
  scsi: lpfc: Fix spelling mistake "unsolicted" -> "unsolicited"
  scsi: qla2xxx: Use transport-defined speed mask for supported_speeds
  scsi: target: iblock: Fold iblock_emulate_read_cap_with_block_size() into iblock_get_blocks()
  scsi: qla2xxx: Fix serialization of DCBX TLV data request
  scsi: ufs: qcom: Remove redundant dev_err() call
  scsi: megaraid_sas: Move megasas_dbg_lvl init to megasas_init()
  scsi: megaraid_sas: Remove unnecessary memset()
  scsi: megaraid_sas: Simplify megasas_update_device_list
  scsi: megaraid_sas: Correct an error message
  scsi: megaraid_sas: Correct value passed to scsi_device_lookup()
  scsi: target: core: UA on all LUNs after reset
  scsi: target: core: New key must be used for moved PR
  scsi: target: core: Abort all preempted regs if requested
  scsi: target: core: Fix memory leak in preempt_and_abort
  ...

Merge tag 'block-6.1-2022-10-28' of git://git.kernel.dk/linux

Pull block fixes from Jens Axboe:

 - NVMe pull request via Christoph:
      - make the multipath dma alignment match the non-multipath one
        (Keith Busch)
      - fix a bogus use of sg_init_marker() (Nam Cao)
      - fix circulr locking in nvme-tcp (Sagi Grimberg)

 - Initialization fix for requests allocated via the special hw queue
   allocator (John)

 - Fix for a regression added in this release with the batched
   completions of end_io backed requests (Ming)

 - Error handling leak fix for rbd (Yang)

 - Error handling leak fix for add_disk() failure (Yu)

* tag 'block-6.1-2022-10-28' of git://git.kernel.dk/linux:
  blk-mq: Properly init requests from blk_mq_alloc_request_hctx()
  blk-mq: don't add non-pt request with ->end_io to batch
  rbd: fix possible memory leak in rbd_sysfs_init()
  nvme-multipath: set queue dma alignment to 3
  nvme-tcp: fix possible circular locking when deleting a controller under memory pressure
  nvme-tcp: replace sg_init_marker() with sg_init_table()
  block: fix memory leak for elevator on add_disk failure

Merge tag 'io_uring-6.1-2022-10-28' of git://git.kernel.dk/linux

Pull io_uring fix from Jens Axboe:
 "Just a fix for a locking regression introduced with the deferred
  task_work running from this merge window"

* tag 'io_uring-6.1-2022-10-28' of git://git.kernel.dk/linux:
  io_uring: unlock if __io_run_local_work locked inside
  io_uring: use io_run_local_work_locked helper

Merge tag 'mm-hotfixes-stable-2022-10-28' of git://git./linux/kernel/git/akpm/mm

Pull misc hotfixes from Andrew Morton:
 "Eight fix pre-6.0 bugs and the remainder address issues which were
  introduced in the 6.1-rc merge cycle, or address issues which aren't
  considered sufficiently serious to warrant a -stable backport"

* tag 'mm-hotfixes-stable-2022-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (23 commits)
  mm: multi-gen LRU: move lru_gen_add_mm() out of IRQ-off region
  lib: maple_tree: remove unneeded initialization in mtree_range_walk()
  mmap: fix remap_file_pages() regression
  mm/shmem: ensure proper fallback if page faults
  mm/userfaultfd: replace kmap/kmap_atomic() with kmap_local_page()
  x86: fortify: kmsan: fix KMSAN fortify builds
  x86: asm: make sure __put_user_size() evaluates pointer once
  Kconfig.debug: disable CONFIG_FRAME_WARN for KMSAN by default
  x86/purgatory: disable KMSAN instrumentation
  mm: kmsan: export kmsan_copy_page_meta()
  mm: migrate: fix return value if all subpages of THPs are migrated successfully
  mm/uffd: fix vma check on userfault for wp
  mm: prep_compound_tail() clear page->private
  mm,madvise,hugetlb: fix unexpected data loss with MADV_DONTNEED on hugetlbfs
  mm/page_isolation: fix clang deadcode warning
  fs/ext4/super.c: remove unused `deprecated_msg'
  ipc/msg.c: fix percpu_counter use after free
  memory tier, sysfs: rename attribute "nodes" to "nodelist"
  MAINTAINERS: git://github.com -> https://github.com for nilfs2
  mm/kmemleak: prevent soft lockup in kmemleak_scan()'s object iteration loops
  ...

Merge tag 'powerpc-6.1-3' of git://git./linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix a case of rescheduling with user access unlocked, when preempt is
   enabled.

 - A follow-up fix for a recent fix, which could lead to IRQ state
   assertions firing incorrectly.

 - Two fixes for lockdep warnings seen when using kfence with the Hash
   MMU.

 - Two fixes for preempt warnings seen when using the Hash MMU.

 - Two fixes for the VAS coprocessor mechanism used on pseries.

 - Prevent building some of our older KVM backends when
   CONTEXT_TRACKING_USER is enabled, as it's known to cause crashes.

 - A couple of fixes for issues seen with PMU NMIs.

Thanks to Nicholas Piggin, Guenter Roeck, Frederic Barrat Haren Myneni,
Sachin Sant, and Samuel Holland.

* tag 'powerpc-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s/interrupt: Fix clear of PACA_IRQS_HARD_DIS when returning to soft-masked context
  powerpc/64s/interrupt: Perf NMI should not take normal exit path
  powerpc/64/interrupt: Prevent NMI PMI causing a dangerous warning
  KVM: PPC: BookS PR-KVM and BookE do not support context tracking
  powerpc: Fix reschedule bug in KUAP-unlocked user copy
  powerpc/64s: Fix hash__change_memory_range preemption warning
  powerpc/64s: Disable preemption in hash lazy mmu mode
  powerpc/64s: make linear_map_hash_lock a raw spinlock
  powerpc/64s: make HPTE lock and native_tlbie_lock irq-safe
  powerpc/64s: Add lockdep for HPTE lock
  powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU
  powerpc/pseries/vas: Add VAS IRQ primary handler

platform/loongarch: laptop: Fix possible UAF and simplify generic_acpi_laptop_init()

Currently the return value of 'sub_driver->init' is not checked. If
sparse_keymap_setup() called in the init function fails, 'generic_
inputdev' is freed, then it will lead a UAF when using it in generic_
acpi_laptop_init(). Fix it by checking the return value and setting
generic_inputdev to NULL after free, so as to avoid double free it.

The error code in generic_subdriver_init() is always negative, so the
return of generic_subdriver_init() can be simplified.

Fixes: 6246ed09111f ("LoongArch: Add ACPI-based generic laptop driver")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

platform/loongarch: laptop: Adjust resume order for loongson_hotkey_resume()

Some laptops don't support SW_LID, but still have backlight control,
move backlight resuming before SW_LID event handling so as to avoid
backlight mistake due to early return.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: BPF: Avoid declare variables in switch-case

Not all compilers support declare variables in switch-case, so move
declarations to the beginning of a function. Otherwise we may get such
build errors:

arch/loongarch/net/bpf_jit.c: In function ‘emit_atomic’:
arch/loongarch/net/bpf_jit.c:362:3: error: a label can only be part of a statement and a declaration is not a statement
   u8 r0 = regmap[BPF_REG_0];
   ^~
arch/loongarch/net/bpf_jit.c: In function ‘build_insn’:
arch/loongarch/net/bpf_jit.c:727:3: error: a label can only be part of a statement and a declaration is not a statement
   u8 t7 = -1;
   ^~
arch/loongarch/net/bpf_jit.c:778:3: error: a label can only be part of a statement and a declaration is not a statement
   int ret;
   ^~~
arch/loongarch/net/bpf_jit.c:779:3: error: expected expression before ‘u64’
   u64 func_addr;
   ^~~
arch/loongarch/net/bpf_jit.c:780:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   bool func_addr_fixed;
   ^~~~
arch/loongarch/net/bpf_jit.c:784:11: error: ‘func_addr’ undeclared (first use in this function); did you mean ‘in_addr’?
          &func_addr, &func_addr_fixed);
           ^~~~~~~~~
           in_addr
arch/loongarch/net/bpf_jit.c:784:11: note: each undeclared identifier is reported only once for each function it appears in
arch/loongarch/net/bpf_jit.c:814:3: error: a label can only be part of a statement and a declaration is not a statement
   u64 imm64 = (u64)(insn + 1)->imm << 32 | (u32)insn->imm;
   ^~~

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Use flexible-array member instead of zero-length array

Eliminate the following coccicheck warning:
./arch/loongarch/include/asm/ptrace.h:32:15-21: WARNING use flexible-array member instead

Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Yushan Zhou <katrinzhou@tencent.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Remove unused kernel stack padding

The current LoongArch kernel stack is padded as if obeying the MIPS o32
calling convention (32 bytes), signifying the port's MIPS lineage but no
longer making sense. Remove the padding for clarity.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Merge tag 's390-6.1-3' of git://git./linux/kernel/git/s390/linux

Pull s390 fixes from Vasily Gorbik:

 - Remove outdated linux390 link from MAINTAINERS

 - Add few missing EX_TABLE entries to inline assemblies

 - Fix raw data collection for pai_ext PMU

 - Add kernel image secure boot trailer for future firmware versions

 - Fix out-of-bounds access on cio_ignore free

 - Fix memory allocation of mdev_types array in vfio-ap

* tag 's390-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/vfio-ap: Fix memory allocation for mdev_types array
  s390/cio: fix out-of-bounds access on cio_ignore free
  s390/pai: fix raw data collection for PMU pai_ext
  s390/boot: add secure boot trailer
  s390/pci: add missing EX_TABLE entries to __pcistg_mio_inuser()/__pcilg_mio_inuser()
  s390/futex: add missing EX_TABLE entry to __futex_atomic_op()
  s390/uaccess: add missing EX_TABLE entries to __clear_user()
  MAINTAINERS: remove outdated linux390 link

Merge tag 'riscv-for-linus-6.1-rc3' of git://git./linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:

 - A fix for a build warning in the jump_label code

 - One of the git://github -> https://github cleanups, for the SiFive
   drivers

 - A fix for the kasan initialization code, this still likely warrants
   some cleanups but that's a bigger problem and at least this fixes the
   crashes in the short term

 - A pair of fixes for extension support detection on mixed LLVM/GNU
   toolchains

 - A fix for a runtime warning in the /proc/cpuinfo code

* tag 'riscv-for-linus-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  RISC-V: Fix /proc/cpuinfo cpumask warning
  riscv: fix detection of toolchain Zihintpause support
  riscv: fix detection of toolchain Zicbom support
  riscv: mm: add missing memcpy in kasan_init
  MAINTAINERS: git://github.com -> https://github.com for sifive
  riscv: jump_label: mark arguments as const to satisfy asm constraints

Merge tag 'acpi-6.1-rc3' of git://git./linux/kernel/git/rafael/linux-pm

Pull ACPI and device properties fixes from Rafael Wysocki:
 "These fix device properties documentation and the ACPI PCC code, add a
  new IRQ override quirk for resource handling and add one more item to
  the list of device IDs to be ignored when returned by _DEP.

  Specifics:

   - Fix the documentation of the *_match_string() family of functions
     to properly cover the return value (Andy Shevchenko)

   - Fix a possible integer overflow during multiplication in the ACPI
     PCC code (Manank Patel)

   - Make the ACPI device resources code skip IRQ override on Asus
     Vivobook S5602ZA (Tamim Khan)

   - Add LATT2021 to the list of device IDs that are ignored when
     returned by _DEP, because there are no drivers for them in the
     kernel and no plans to add such drivers (Hans de Goede)"

* tag 'acpi-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: scan: Add LATT2021 to acpi_ignore_dep_ids[]
  ACPI: resource: Skip IRQ override on Asus Vivobook S5602ZA
  ACPI: PCC: Fix unintentional integer overflow
  device property: Fix documentation for *_match_string() APIs

Merge tag 'pm-6.1-rc3' of git://git./linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "These make the intel_pstate driver work as expected on all hybrid
  platforms to date (regardless of possible platform firmware issues),
  fix hybrid sleep on systems using suspend-to-idle by default, make the
  generic power domains code handle disabled idle states properly and
  update pm-graph.

  Specifics:

   - Make intel_pstate use what is known about the hardware instead of
     relying on information from the platform firmware (ACPI CPPC in
     particular) to establish the relationship between the HWP CPU
     performance levels and frequencies on all hybrid platforms
     available to date (Rafael Wysocki)

   - Allow hybrid sleep to use suspend-to-idle as a system suspend
     method if it is the current suspend method of choice (Mario
     Limonciello)

   - Fix handling of unavailable/disabled idle states in the generic
     power domains code (Sudeep Holla)

   - Update the pm-graph suite of utilities to version 5.10 which is
     fixes-mostly and does not add any new features (Todd Brandt)"

* tag 'pm-6.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM: domains: Fix handling of unavailable/disabled idle states
  pm-graph v5.10
  cpufreq: intel_pstate: hybrid: Use known scaling factor for P-cores
  cpufreq: intel_pstate: Read all MSRs on the target CPU
  PM: hibernate: Allow hybrid sleep to work with s2idle

random: use arch_get_random*_early() in random_init()

While reworking the archrandom handling, commit d349ab99eec7 ("random:
handle archrandom with multiple longs") switched to the non-early
archrandom helpers in random_init(), which broke initialization of the
entropy pool from the arm64 random generator.

Indeed at that point the arm64 CPU features, which verify that all CPUs
have compatible capabilities, are not finalized so arch_get_random_seed_longs()
is unsuccessful. Instead random_init() should use the _early functions,
which check only the boot CPU on arm64. On other architectures the
_early functions directly call the normal ones.

Fixes: d349ab99eec7 ("random: handle archrandom with multiple longs")
Cc: stable@vger.kernel.org
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

mm: multi-gen LRU: move lru_gen_add_mm() out of IRQ-off region

lru_gen_add_mm() has been added within an IRQ-off region in the commit
mentioned below.  The other invocations of lru_gen_add_mm() are not within
an IRQ-off region.

The invocation within IRQ-off region is problematic on PREEMPT_RT because
the function is using a spin_lock_t which must not be used within
IRQ-disabled regions.

The other invocations of lru_gen_add_mm() occur while
task_struct::alloc_lock is acquired.  Move lru_gen_add_mm() after
interrupts are enabled and before task_unlock().

Link: https://lkml.kernel.org/r/20221026134830.711887-1-bigeasy@linutronix.de
Fixes: bd74fdaea1460 ("mm: multi-gen LRU: support page table walks")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib: maple_tree: remove unneeded initialization in mtree_range_walk()

Before the do-while loop in mtree_range_walk(), the variables next, min,
max need to be initialized.  The variables last, prev_min and prev_max are
set within the loop body before they are eventually used after exiting the
loop body.

As it is a do-while loop, the loop body is executed at least once, so the
variables last, prev_min and prev_max do not need to be initialized before
the loop body.

Remove unneeded initialization of last and prev_min.

The needless initialization was reported by clang-analyzer as Dead Stores.

As the compiler already identifies these assignments as unneeded, it
optimizes the assignments away.  Hence:

No functional change. No change in object code.

Link: https://lkml.kernel.org/r/20221026120029.12555-2-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mmap: fix remap_file_pages() regression

When using the VMA iterator, the final execution will set the variable
'next' to NULL which causes the function to fail out.  Restore the break
in the loop to exit the VMA iterator early without clearing NULL fixes the
issue.

Link: https://lore.kernel.org/lkml/29344.1666681759@jrobl/
Link: https://lkml.kernel.org/r/20221025161222.2634030-1-Liam.Howlett@oracle.com
Fixes: 763ecb035029 (mm: remove the vma linked list)
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: "J. R. Okajima" <hooanon05g@gmail.com>
Tested-by: "J. R. Okajima" <hooanon05g@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/shmem: ensure proper fallback if page faults

The kernel test robot flagged a recursive lock as a result of a conversion
from kmap_atomic() to kmap_local_folio()[Link]

The cause was due to the code depending on the kmap_atomic() side effect
of disabling page faults.  In that case the code expects the fault to fail
and take the fallback case.

git archaeology implied that the recursion may not be an actual bug.[1]
However, depending on the implementation of the mmap_lock and the
condition of the call there may still be a deadlock.[2] So this is not
purely a lockdep issue.  Considering a single threaded call stack there
are 3 options.

1) Different mm's are in play (no issue)
2) Readlock implementation is recursive and same mm is in play
   (no issue)
3) Readlock implementation is _not_ recursive (issue)

The mmap_lock is recursive so with a single thread there is no issue.

However, Matthew pointed out a deadlock scenario when you consider
additional process' and threads thusly.

"The readlock implementation is only recursive if nobody else has taken a
write lock.  If you have a multithreaded process, one of the other threads
can call mmap() and that will prevent recursion (due to fairness).  Even
if it's a different process that you're trying to acquire the mmap read
lock on, you can still get into a deadly embrace.  eg:

process A thread 1 takes read lock on own mmap_lock
process A thread 2 calls mmap, blocks taking write lock
process B thread 1 takes page fault, read lock on own mmap lock
process B thread 2 calls mmap, blocks taking write lock
process A thread 1 blocks taking read lock on process B
process B thread 1 blocks taking read lock on process A

Now all four threads are blocked waiting for each other."

Regardless using pagefault_disable() ensures that no matter what locking
implementation is used a deadlock will not occur.  Add an explicit
pagefault_disable() and a big comment to explain this for future souls
looking at this code.

[1] https://lore.kernel.org/all/Y1MymJ%2FINb45AdaY@iweiny-desk3/
[2] https://lore.kernel.org/lkml/Y1bXBtGTCym77%2FoD@casper.infradead.org/

Link: https://lkml.kernel.org/r/20221025220108.2366043-1-ira.weiny@intel.com
Link: https://lore.kernel.org/r/202210211215.9dc6efb5-yujie.liu@intel.com
Fixes: 7a7256d5f512 ("shmem: convert shmem_mfill_atomic_pte() to use a folio")
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: kernel test robot <yujie.liu@intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>