On Thu, Sep 14, 2023 at 08:44:06PM +0206, John Ogness wrote: > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > When a serial port is used for kernel console output, then all > modifications to the UART registers which are done from other contexts, > e.g. getty, termios, are interference points for the kernel console. > > So far this has been ignored and the printk output is based on the > principle of hope. The rework of the console infrastructure which aims to > support threaded and atomic consoles, requires to mark sections which > modify the UART registers as unsafe. This allows the atomic write function > to make informed decisions and eventually to restore operational state. It > also allows to prevent the regular UART code from modifying UART registers > while printk output is in progress. > > All modifications of UART registers are guarded by the UART port lock, > which provides an obvious synchronization point with the console > infrastructure. > > To avoid adding this functionality to all UART drivers, wrap the > spin_[un]lock*() invocations for uart_port::lock into helper functions > which just contain the spin_[un]lock*() invocations for now. In a > subsequent step these helpers will gain the console synchronization > mechanisms. > > Converted with coccinelle. No functional change. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx> > --- > drivers/tty/serial/qcom_geni_serial.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c > index b8aa4c1293ba..7e78f97e8f43 100644 > --- a/drivers/tty/serial/qcom_geni_serial.c > +++ b/drivers/tty/serial/qcom_geni_serial.c > @@ -482,9 +482,9 @@ static void qcom_geni_serial_console_write(struct console *co, const char *s, > > uport = &port->uport; > if (oops_in_progress) > - locked = spin_trylock_irqsave(&uport->lock, flags); > + locked = uart_port_trylock_irqsave(uport, &flags); > else > - spin_lock_irqsave(&uport->lock, flags); > + uart_port_lock_irqsave(uport, &flags); > > geni_status = readl(uport->membase + SE_GENI_STATUS); > > @@ -520,7 +520,7 @@ static void qcom_geni_serial_console_write(struct console *co, const char *s, > qcom_geni_serial_setup_tx(uport, port->tx_remaining); > > if (locked) > - spin_unlock_irqrestore(&uport->lock, flags); > + uart_port_unlock_irqrestore(uport, flags); > } > > static void handle_rx_console(struct uart_port *uport, u32 bytes, bool drop) > @@ -970,7 +970,7 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev) > if (uport->suspended) > return IRQ_NONE; > > - spin_lock(&uport->lock); > + uart_port_lock(uport); > Nice, now this no longer look unbalanced with the unlock in uart_port_unlock_irqrestore(). Regards, Bjorn > m_irq_status = readl(uport->membase + SE_GENI_M_IRQ_STATUS); > s_irq_status = readl(uport->membase + SE_GENI_S_IRQ_STATUS); > -- > 2.39.2 >
