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serial: 8250: Flush DMA Rx on RLSI

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commit 1980860e0c8299316cddaf0992dd9e1258ec9d88 upstream.

Returning true from handle_rx_dma() without flushing DMA first creates
a data ordering hazard. If DMA Rx has handled any character at the
point when RLSI occurs, the non-DMA path handles any pending characters
jumping them ahead of those characters that are pending under DMA.

Fixes: 75df022b5f ("serial: 8250_dma: Fix RX handling")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221108121952.5497-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ilpo Järvinen 2022-11-08 14:19:52 +02:00 committed by Greg Kroah-Hartman
parent e7061dd1fe
commit 32a7f06451
1 changed files with 1 additions and 2 deletions
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3
drivers/tty/serial/8250/8250_port.c
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@ -1824,10 +1824,9 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
if (!up->dma->rx_running) if (!up->dma->rx_running)
break; break;
fallthrough; fallthrough;
case UART_IIR_RLSI:
case UART_IIR_RX_TIMEOUT: case UART_IIR_RX_TIMEOUT:
serial8250_rx_dma_flush(up); serial8250_rx_dma_flush(up);
/* fall-through */
case UART_IIR_RLSI:
return true; return true;
} }
return up->dma->rx_dma(up); return up->dma->rx_dma(up);