From 0e4f7f920a5c6bfe5e851e989f27b35a0cc7fb7e Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Wed, 27 Nov 2019 22:15:43 +0800 Subject: tty: serial: msm_serial: Fix lockup for sysrq and oops As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug") has mentioned the uart driver might cause recursive locking between normal printing and the kernel debugging facilities (e.g. sysrq and oops). In the commit it gave out suggestion for fixing recursive locking issue: "The solution is to avoid locking in the sysrq case and trylock in the oops_in_progress case." This patch follows the suggestion (also used the exactly same code with other serial drivers, e.g. amba-pl011.c) to fix the recursive locking issue, this can avoid stuck caused by deadlock and print out log for sysrq and oops. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Leo Yan Reviewed-by: Jeffrey Hugo Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/msm_serial.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 1cbae0768b1f..f6c45a796433 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -1580,6 +1580,7 @@ static void __msm_console_write(struct uart_port *port, const char *s, int num_newlines = 0; bool replaced = false; void __iomem *tf; + int locked = 1; if (is_uartdm) tf = port->membase + UARTDM_TF; @@ -1592,7 +1593,13 @@ static void __msm_console_write(struct uart_port *port, const char *s, num_newlines++; count += num_newlines; - spin_lock(&port->lock); + if (port->sysrq) + locked = 0; + else if (oops_in_progress) + locked = spin_trylock(&port->lock); + else + spin_lock(&port->lock); + if (is_uartdm) msm_reset_dm_count(port, count); @@ -1628,7 +1635,9 @@ static void __msm_console_write(struct uart_port *port, const char *s, iowrite32_rep(tf, buf, 1); i += num_chars; } - spin_unlock(&port->lock); + + if (locked) + spin_unlock(&port->lock); } static void msm_console_write(struct console *co, const char *s, -- cgit v1.2.3-58-ga151 From abeb2e9414d7e3a0d8417bc3b13d7172513ea8a0 Mon Sep 17 00:00:00 2001 From: Yonghan Ye Date: Wed, 4 Dec 2019 20:00:07 +0800 Subject: serial: sprd: Add clearing break interrupt operation A break interrupt will be generated if the RX line was pulled low, which means some abnomal behaviors occurred of the UART. In this case, we still need to clear this break interrupt status, otherwise it will cause irq storm to crash the whole system. Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support") Signed-off-by: Yonghan Ye Cc: stable Signed-off-by: Baolin Wang Link: https://lore.kernel.org/r/925e51b73099c90158e080b8f5bed9b3b38c4548.1575460601.git.baolin.wang7@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sprd_serial.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c index 31df23502562..f60a59d9bf27 100644 --- a/drivers/tty/serial/sprd_serial.c +++ b/drivers/tty/serial/sprd_serial.c @@ -679,6 +679,9 @@ static irqreturn_t sprd_handle_irq(int irq, void *dev_id) if (ims & SPRD_IMSR_TIMEOUT) serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT); + if (ims & SPRD_IMSR_BREAK_DETECT) + serial_out(port, SPRD_ICLR, SPRD_IMSR_BREAK_DETECT); + if (ims & (SPRD_IMSR_RX_FIFO_FULL | SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT)) sprd_rx(port); -- cgit v1.2.3-58-ga151 From fb2b90014d782d80d7ebf663e50f96d8c507a73c Mon Sep 17 00:00:00 2001 From: Sudip Mukherjee Date: Thu, 12 Dec 2019 13:16:02 +0000 Subject: tty: link tty and port before configuring it as console There seems to be a race condition in tty drivers and I could see on many boot cycles a NULL pointer dereference as tty_init_dev() tries to do 'tty->port->itty = tty' even though tty->port is NULL. 'tty->port' will be set by the driver and if the driver has not yet done it before we open the tty device we can get to this situation. By adding some extra debug prints, I noticed that: 6.650130: uart_add_one_port 6.663849: register_console 6.664846: tty_open 6.674391: tty_init_dev 6.675456: tty_port_link_device uart_add_one_port() registers the console, as soon as it registers, the userspace tries to use it and that leads to tty_open() but uart_add_one_port() has not yet done tty_port_link_device() and so tty->port is not yet configured when control reaches tty_init_dev(). Further look into the code and tty_port_link_device() is done by uart_add_one_port(). After registering the console uart_add_one_port() will call tty_port_register_device_attr_serdev() and tty_port_link_device() is called from this. Call add tty_port_link_device() before uart_configure_port() is done and add a check in tty_port_link_device() so that it only links the port if it has not been done yet. Suggested-by: Jiri Slaby Signed-off-by: Sudip Mukherjee Cc: stable Link: https://lore.kernel.org/r/20191212131602.29504-1-sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 1 + drivers/tty/tty_port.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index b0a6eb106edb..7c2782785736 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2834,6 +2834,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) if (uport->cons && uport->dev) of_console_check(uport->dev->of_node, uport->cons->name, uport->line); + tty_port_link_device(port, drv->tty_driver, uport->line); uart_configure_port(drv, state, uport); port->console = uart_console(uport); diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index 044c3cbdcfa4..5023c85ebc6e 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -89,7 +89,8 @@ void tty_port_link_device(struct tty_port *port, { if (WARN_ON(index >= driver->num)) return; - driver->ports[index] = port; + if (!driver->ports[index]) + driver->ports[index] = port; } EXPORT_SYMBOL_GPL(tty_port_link_device); -- cgit v1.2.3-58-ga151 From cb47b9f8630ae3fa3f5fbd0c7003faba7abdf711 Mon Sep 17 00:00:00 2001 From: David Engraf Date: Mon, 16 Dec 2019 09:54:03 +0100 Subject: tty/serial: atmel: fix out of range clock divider handling Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode register was already written thus the clock selection is ignored. Fix by doing the baud rate calulation before setting the mode. Fixes: 5bf5635ac170 ("tty/serial: atmel: add fractional baud rate support") Signed-off-by: David Engraf Acked-by: Ludovic Desroches Acked-by: Richard Genoud Cc: stable Link: https://lore.kernel.org/r/20191216085403.17050-1-david.engraf@sysgo.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 43 ++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 21 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index a8dc8af83f39..1ba9bc667e13 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2270,27 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, mode |= ATMEL_US_USMODE_NORMAL; } - /* set the mode, clock divisor, parity, stop bits and data size */ - atmel_uart_writel(port, ATMEL_US_MR, mode); - - /* - * when switching the mode, set the RTS line state according to the - * new mode, otherwise keep the former state - */ - if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) { - unsigned int rts_state; - - if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) { - /* let the hardware control the RTS line */ - rts_state = ATMEL_US_RTSDIS; - } else { - /* force RTS line to low level */ - rts_state = ATMEL_US_RTSEN; - } - - atmel_uart_writel(port, ATMEL_US_CR, rts_state); - } - /* * Set the baud rate: * Fractional baudrate allows to setup output frequency more @@ -2317,6 +2296,28 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) atmel_uart_writel(port, ATMEL_US_BRGR, quot); + + /* set the mode, clock divisor, parity, stop bits and data size */ + atmel_uart_writel(port, ATMEL_US_MR, mode); + + /* + * when switching the mode, set the RTS line state according to the + * new mode, otherwise keep the former state + */ + if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) { + unsigned int rts_state; + + if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) { + /* let the hardware control the RTS line */ + rts_state = ATMEL_US_RTSDIS; + } else { + /* force RTS line to low level */ + rts_state = ATMEL_US_RTSEN; + } + + atmel_uart_writel(port, ATMEL_US_CR, rts_state); + } + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX); atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN); atmel_port->tx_stopped = false; -- cgit v1.2.3-58-ga151