On Wed, 15 Jun 2022, Andy Shevchenko wrote: > On Wed, Jun 15, 2022 at 12:06:50PM +0300, Ilpo Järvinen wrote: > > Accessing LSR requires port lock because it mutates lsr_saved_flags > > in serial_lsr_in(). > > I got this as patch 2/3, where are the 1/3 and 3/3? That's probably because get_maintainer.pl didn't pick you up for the other patches and I didn't explicitly send them to you. Here they are: https://lore.kernel.org/linux-serial/20220615090651.15340-1-ilpo.jarvinen@xxxxxxxxxxxxxxx/T/#t > > @@ -266,7 +266,10 @@ static int dw8250_handle_irq(struct uart_port *p) > > > > /* Manually stop the Rx DMA transfer when acting as flow controller */ > > if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) { > > + spin_lock_irqsave(&p->lock, flags); > > status = serial_lsr_in(up); > > + spin_unlock_irqrestore(&p->lock, flags); > > This reminds me the question, why do we need to save flags here? Aren't we in > IRQ context already? (Perhaps another patch might be issued.) Currently serial8250_handle_irq() reads from LSR again. I guess it would be possible to read LSR only once and pass it as a parameter. It would require some rework though. -- i.
