From: Ilpo Järvinen ilpo.jarvinen@linux.intel.com
commit 31352811e13dc2313f101b890fd4b1ce760b5fe7 upstream.
__dma_rx_complete() is called from two places: - Through the DMA completion callback dma_rx_complete() - From serial8250_rx_dma_flush() after IIR_RLSI or IIR_RX_TIMEOUT The former does not hold port's lock during __dma_rx_complete() which allows these two to race and potentially insert the same data twice.
Extend port's lock coverage in dma_rx_complete() to prevent the race and check if the DMA Rx is still pending completion before calling into __dma_rx_complete().
Reported-by: Gilles BULOZ gilles.buloz@kontron.com Tested-by: Gilles BULOZ gilles.buloz@kontron.com Fixes: 9ee4b83e51f7 ("serial: 8250: Add support for dmaengine") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Link: https://lore.kernel.org/r/20230130114841.25749-2-ilpo.jarvinen@linux.intel.c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/8250/8250_dma.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -59,6 +59,18 @@ static void __dma_rx_complete(void *para tty_flip_buffer_push(tty_port); }
+static void dma_rx_complete(void *param) +{ + struct uart_8250_port *p = param; + struct uart_8250_dma *dma = p->dma; + unsigned long flags; + + spin_lock_irqsave(&p->port.lock, flags); + if (dma->rx_running) + __dma_rx_complete(p); + spin_unlock_irqrestore(&p->port.lock, flags); +} + int serial8250_tx_dma(struct uart_8250_port *p) { struct uart_8250_dma *dma = p->dma; @@ -121,7 +133,7 @@ int serial8250_rx_dma(struct uart_8250_p return -EBUSY;
dma->rx_running = 1; - desc->callback = __dma_rx_complete; + desc->callback = dma_rx_complete; desc->callback_param = p;
dma->rx_cookie = dmaengine_submit(desc);