serial: 8250: Fix lost rx state
When max_count is reached, the rx loop exits. However, UART_LSR has already been read so those char flags are lost, and subsequent rx status will be for the wrong byte until the rx fifo drains. Reported-by: George Spelvin <linux@horizon.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1478,16 +1478,17 @@ static void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
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* value, and returns the remaining LSR bits not handled
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* by this Rx routine.
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*/
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unsigned char
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serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
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unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
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{
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struct uart_port *port = &up->port;
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int max_count = 256;
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do {
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serial8250_read_char(up, lsr);
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if (--max_count == 0)
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break;
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lsr = serial_in(up, UART_LSR);
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} while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (--max_count > 0));
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} while (lsr & (UART_LSR_DR | UART_LSR_BI));
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spin_unlock(&port->lock);
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tty_flip_buffer_push(&port->state->port);
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spin_lock(&port->lock);
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