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HUPCL1008drivers/char/serial.cif (!info->tty || (info->tty->termios->c_cflag & HUPCL)) {
HUPCL2206drivers/char/serial.cB9600 | CS8 | CREAD | HUPCL | CLOCAL;
HUPCL151include/linux/tty.h#define C_HUPCL(tty)  _C_FLAG((tty),HUPCL)