On Thu, 14 Sep 2023, 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> > --- > drivers/tty/serial/8250/8250_dma.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c > index 7fa66501792d..8b30ca8fdd3f 100644 > --- a/drivers/tty/serial/8250/8250_dma.c > +++ b/drivers/tty/serial/8250/8250_dma.c > @@ -22,7 +22,7 @@ static void __dma_tx_complete(void *param) > dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr, > UART_XMIT_SIZE, DMA_TO_DEVICE); > > - spin_lock_irqsave(&p->port.lock, flags); > + uart_port_lock_irqsave(&p->port, &flags); > > dma->tx_running = 0; > > @@ -35,7 +35,7 @@ static void __dma_tx_complete(void *param) > if (ret || !dma->tx_running) > serial8250_set_THRI(p); > > - spin_unlock_irqrestore(&p->port.lock, flags); > + uart_port_unlock_irqrestore(&p->port, flags); > } > > static void __dma_rx_complete(struct uart_8250_port *p) > @@ -70,7 +70,7 @@ static void dma_rx_complete(void *param) > struct uart_8250_dma *dma = p->dma; > unsigned long flags; > > - spin_lock_irqsave(&p->port.lock, flags); > + uart_port_lock_irqsave(&p->port, &flags); > if (dma->rx_running) > __dma_rx_complete(p); > > @@ -80,7 +80,7 @@ static void dma_rx_complete(void *param) > */ > if (!dma->rx_running && (serial_lsr_in(p) & UART_LSR_DR)) > p->dma->rx_dma(p); > - spin_unlock_irqrestore(&p->port.lock, flags); > + uart_port_unlock_irqrestore(&p->port, flags); > } > > int serial8250_tx_dma(struct uart_8250_port *p) Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx> -- i.
