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d72402145a
linux/drivers/tty/serial
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Sergey Senozhatsky d72402145a tty/serial: do not free trasnmit buffer page under port lock 
LKP has hit yet another circular locking dependency between uart
console drivers and debugobjects [1]:

     CPU0                                    CPU1

                                            rhltable_init()
                                             __init_work()
                                              debug_object_init
     uart_shutdown()                          /* db->lock */
      /* uart_port->lock */                    debug_print_object()
       free_page()                              printk()
                                                 call_console_drivers()
        debug_check_no_obj_freed()                /* uart_port->lock */
         /* db->lock */
          debug_print_object()

So there are two dependency chains:
	uart_port->lock -> db->lock
And
	db->lock -> uart_port->lock

This particular circular locking dependency can be addressed in several
ways:

a) One way would be to move debug_print_object() out of db->lock scope
   and, thus, break the db->lock -> uart_port->lock chain.
b) Another one would be to free() transmit buffer page out of db->lock
   in UART code; which is what this patch does.

It makes sense to apply a) and b) independently: there are too many things
going on behind free(), none of which depend on uart_port->lock.

The patch fixes transmit buffer page free() in uart_shutdown() and,
additionally, in uart_port_startup() (as was suggested by Dmitry Safonov).

[1] https://lore.kernel.org/lkml/20181211091154.GL23332@shao2-debian/T/#u
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-17 16:11:23 +01:00
..
8250 serial: 8250: Rate limit serial port rx interrupts during input overruns 2018-12-17 16:02:57 +01:00
cpm_uart mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
jsm tty: serial: jsm: remove redundant pointer ch 2018-07-13 15:36:32 +02:00
21285.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
altera_jtaguart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
altera_uart.c serial: altera: set RRDY flag also without irq 2018-02-28 13:30:09 +01:00
amba-pl010.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
amba-pl011.c serial: set suppress_bind_attrs flag only if builtin 2018-11-09 09:07:17 -08:00
amba-pl011.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
apbuart.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
apbuart.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ar933x_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
arc_uart.c serial: arc_uart: Fix out-of-bounds access through DT alias 2018-02-28 15:29:59 +01:00
atmel_serial.c tty/serial: atmel: add ISO7816 support 2018-10-02 13:38:55 -07:00
atmel_serial.h tty/serial: atmel: add ISO7816 support 2018-10-02 13:38:55 -07:00
bcm63xx_uart.c MIPS changes for 4.15 2017-11-15 11:36:08 -08:00
clps711x.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
digicolor-usart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
dz.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
dz.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
earlycon-arm-semihost.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
earlycon.c earlycon: Remove hardcoded port->uartclk initialization in of_setup_earlycon 2018-05-14 13:41:05 +02:00
efm32-uart.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
fsl_lpuart.c serial: fsl_lpuart: clear parity enable bit when disable parity 2018-11-09 08:48:57 -08:00
icom.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
icom.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ifx6x60.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
ifx6x60.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
imx.c serial: imx: fix error handling in console_setup 2018-11-27 09:56:20 +01:00
ioc3_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ioc4_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
ip22zilog.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
ip22zilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig tty/serial: atmel: Change the driver to work under at91-usart MFD 2018-09-10 16:12:43 +01:00
kgdb_nmi.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
kgdboc.c kgdboc: fix KASAN global-out-of-bounds bug in param_set_kgdboc_var() 2018-12-06 15:59:07 +01:00
lantiq.c serial: lantiq: Change init_lqasc to static declaration 2018-11-09 08:43:27 -08:00
lpc32xx_hs.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
Makefile TTY/Serial driver patches for 4.17-rc1 2018-04-04 18:43:49 -07:00
max310x.c serial: max310x: Check the clock readiness 2018-06-28 21:07:54 +09:00
max3100.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
mcf.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
men_z135_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
meson_uart.c tty: serial: meson: fix typo in the "stop bit" register definition 2017-11-28 15:32:33 +01:00
mpc52xx_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
mps2-uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
mpsc.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
msm_serial.c tty: serial: msm_serial: Add __maybe_unused to suspend/resume callbacks 2018-05-14 13:41:05 +02:00
mux.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
mvebu-uart.c serial: mvebu-uart: initialize over sampling stack register 2018-11-27 09:20:17 +01:00
mxs-auart.c serial: mxs-auart: Fix potential infinite loop 2018-09-18 16:07:24 +02:00
netx-serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
omap-serial.c tty: omap-serial: Fix initial on-boot RTS GPIO level 2018-01-09 16:45:17 +01:00
owl-uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
pch_uart.c pch_uart: remove set but not used variable 'tx_empty' 2018-11-09 09:07:17 -08:00
pic32_uart.c serial: set suppress_bind_attrs flag only if builtin 2018-11-09 09:07:17 -08:00
pic32_uart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
pmac_zilog.c tty: serial: remove set but not used variable 'error' 2018-09-20 13:33:15 +02:00
pmac_zilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pnx8xxx_uart.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
pxa.c serial: pxa: Fix an error handling path in 'serial_pxa_probe()' 2018-06-28 21:07:54 +09:00
qcom_geni_serial.c tty: serial: qcom_geni_serial: Remove interrupt storm 2018-12-17 15:06:46 +01:00
rp2.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
sa1100.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
samsung.c serial: samsung: Enable baud clock for UART reset procedure in resume 2018-09-18 16:07:24 +02:00
samsung.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sb1250-duart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sc16is7xx.c sc16is7xx: Fix for "Unexpected interrupt: 8" 2018-09-18 16:07:25 +02:00
sccnxp.c headers: separate linux/mod_devicetable.h from linux/platform_device.h 2018-07-07 17:52:26 +02:00
serial_core.c tty/serial: do not free trasnmit buffer page under port lock 2018-12-17 16:11:23 +01:00
serial_ks8695.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial_mctrl_gpio.c gpiolib: Pass array info to get/set array functions 2018-09-13 11:16:54 +02:00
serial_mctrl_gpio.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial_txx9.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
serial-tegra.c serial: tegra: fix some spelling mistakes 2018-11-09 08:58:18 -08:00
sh-sci.c serial: sh-sci: Resume PIO in sci_rx_interrupt() on DMA failure 2018-12-17 15:04:11 +01:00
sh-sci.h serial: sh-sci: Support for HSCIF RX sampling point adjustment 2018-04-23 10:08:18 +02:00
sirfsoc_uart.c serial: sirf: Fix out-of-bounds access through DT alias 2018-02-28 15:30:00 +01:00
sirfsoc_uart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
sn_console.c TTY: sn_console: Replace spin_is_locked() with spin_trylock() 2018-10-04 11:06:35 -07:00
sprd_serial.c serial: sprd: Fix the indentation issue 2018-09-18 16:07:24 +02:00
st-asc.c tty: serial: simplify getting .drvdata 2018-04-22 17:29:43 +02:00
stm32-usart.c serial: stm32: fix initialization of RS485 mode 2018-03-15 17:39:43 +01:00
stm32-usart.h serial: stm32: add support for RS485 hardware control mode 2018-03-14 13:35:37 +01:00
suncore.c drivers/tty: add missing of_node_put() 2018-12-02 20:55:23 -08:00
sunhv.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunsab.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
sunsab.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sunsu.c Revert "serial/sunsu: add missing of_node_put()" 2018-12-05 10:53:42 +01:00
sunzilog.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
sunzilog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
timbuart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
timbuart.h tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
uartlite.c serial-uartlite: fix null pointer dereference on pointer port 2018-11-27 09:08:15 +01:00
ucc_uart.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
vr41xx_siu.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
vt8500_serial.c tty: serial: Remove redundant license text 2017-11-08 13:08:12 +01:00
xilinx_uartps.c Revert "tty: xilinx_uartps: Correct return value in probe" 2018-12-06 12:47:22 +01:00
zs.c tty: add SPDX identifiers to all remaining files in drivers/tty/ 2017-11-08 13:08:12 +01:00
zs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00