2588aba002
pch_uart_interrupt() takes priv->port.lock which leads to two recursive
spinlock calls if low_latency==1 or CONFIG_PREEMPT_RT_FULL=y (one
otherwise):
pch_uart_interrupt
spin_lock_irqsave(priv->port.lock, flags)
case PCH_UART_IID_RDR_TO (data ready)
handle_rx_to
push_rx
tty_port_tty_get
spin_lock_irqsave(&port->lock, flags) <--- already hold this lock
...
tty_flip_buffer_push
...
flush_to_ldisc
spin_lock_irqsave(&tty->buf.lock)
spin_lock_irqsave(&tty->buf.lock)
disc->ops->receive_buf(tty, char_buf)
n_tty_receive_buf
tty->ops->flush_chars()
uart_flush_chars
uart_start
spin_lock_irqsave(&port->lock) <--- already hold this lock
Avoid this by using a dedicated lock to protect the eg20t_port structure
and IO access to its membase. This is more consistent with the 8250
driver. Ensure priv->lock is always take prior to priv->port.lock when
taken at the same time.
V2: Remove inadvertent whitespace change.
V3: Account for oops_in_progress for the private lock in
pch_console_write().
Note: Like the 8250 driver, if a printk is introduced anywhere inside
the pch_console_write() critical section, the kernel will hang
on a recursive spinlock on the private lock. The oops case is
handled by using a trylock in the oops_in_progress case.
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
CC: Tomoya MORINAGA <tomoya.rohm@gmail.com>
CC: Feng Tang <feng.tang@intel.com>
CC: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
|---|---|---|
| .. | ||
| 8250 | ||
| cpm_uart | ||
| jsm | ||
| 21285.c | ||
| 68328serial.c | ||
| Kconfig | ||
| Makefile | ||
| altera_jtaguart.c | ||
| altera_uart.c | ||
| amba-pl010.c | ||
| amba-pl011.c | ||
| apbuart.c | ||
| apbuart.h | ||
| ar933x_uart.c | ||
| atmel_serial.c | ||
| bcm63xx_uart.c | ||
| bfin_sport_uart.c | ||
| bfin_sport_uart.h | ||
| bfin_uart.c | ||
| clps711x.c | ||
| crisv10.c | ||
| crisv10.h | ||
| dz.c | ||
| dz.h | ||
| efm32-uart.c | ||
| icom.c | ||
| icom.h | ||
| ifx6x60.c | ||
| ifx6x60.h | ||
| imx.c | ||
| ioc3_serial.c | ||
| ioc4_serial.c | ||
| ip22zilog.c | ||
| ip22zilog.h | ||
| kgdboc.c | ||
| lantiq.c | ||
| m32r_sio.c | ||
| m32r_sio.h | ||
| m32r_sio_reg.h | ||
| max3100.c | ||
| max3107.c | ||
| max3107.h | ||
| mcf.c | ||
| mfd.c | ||
| mpc52xx_uart.c | ||
| mpsc.c | ||
| mrst_max3110.c | ||
| mrst_max3110.h | ||
| msm_serial.c | ||
| msm_serial.h | ||
| msm_serial_hs.c | ||
| msm_smd_tty.c | ||
| mux.c | ||
| mxs-auart.c | ||
| netx-serial.c | ||
| nwpserial.c | ||
| of_serial.c | ||
| omap-serial.c | ||
| pch_uart.c | ||
| pmac_zilog.c | ||
| pmac_zilog.h | ||
| pnx8xxx_uart.c | ||
| pxa.c | ||
| sa1100.c | ||
| samsung.c | ||
| samsung.h | ||
| sb1250-duart.c | ||
| sc26xx.c | ||
| serial_core.c | ||
| serial_ks8695.c | ||
| serial_txx9.c | ||
| sh-sci.c | ||
| sh-sci.h | ||
| sirfsoc_uart.c | ||
| sirfsoc_uart.h | ||
| sn_console.c | ||
| suncore.c | ||
| sunhv.c | ||
| sunsab.c | ||
| sunsab.h | ||
| sunsu.c | ||
| sunzilog.c | ||
| sunzilog.h | ||
| timbuart.c | ||
| timbuart.h | ||
| uartlite.c | ||
| ucc_uart.c | ||
| vr41xx_siu.c | ||
| vt8500_serial.c | ||
| xilinx_uartps.c | ||
| zs.c | ||
| zs.h | ||