BUG: KCSAN: data-race in ppp_asynctty_receive / tty_set_termios

read-write to 0xffff888112bac908 of 4 bytes by task 11591 on cpu 0:
 unset_locked_termios drivers/tty/tty_ioctl.c:214 [inline]
 tty_set_termios+0xfa/0x8b0 drivers/tty/tty_ioctl.c:340
 set_termios+0x497/0x4e0 drivers/tty/tty_ioctl.c:516
 tty_mode_ioctl+0x391/0x5d0
read to 0xffff888112bac908 of 4 bytes by task 1653 on cpu 1:
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
Reported by Kernel Concurrency Sanitizer on: