Commit 238b48d2 authored by Richard Genoud's avatar Richard Genoud Committed by Jiri Slaby

tty/serial: atmel: fix race condition (TX+DMA)

commit 31ca2c63 upstream.

If uart_flush_buffer() is called between atmel_tx_dma() and
atmel_complete_tx_dma(), the circular buffer has been cleared, but not
atmel_port->tx_len.
That leads to a circular buffer overflow (dumping (UART_XMIT_SIZE -
atmel_port->tx_len) bytes).
Tested-by: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
[rg] backport to 3.12
Signed-off-by: default avatarRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
parent f60473f8
...@@ -1690,6 +1690,11 @@ static void atmel_flush_buffer(struct uart_port *port) ...@@ -1690,6 +1690,11 @@ static void atmel_flush_buffer(struct uart_port *port)
UART_PUT_TCR(port, 0); UART_PUT_TCR(port, 0);
atmel_port->pdc_tx.ofs = 0; atmel_port->pdc_tx.ofs = 0;
} }
/*
* in uart_flush_buffer(), the xmit circular buffer has just
* been cleared, so we have to reset its length accordingly.
*/
sg_dma_len(&atmel_port->sg_tx) = 0;
} }
/* /*
......
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