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BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff88816a96d527 of 1 bytes by task 31133 on cpu 1:
 unset_locked_termios drivers/tty/tty_ioctl.c:257 [inline]
 tty_set_termios+0x40a/0x8a0 drivers/tty/tty_ioctl.c:331
 set_termios+0x375/0x3b0 drivers/tty/tty_ioctl.c:414
 tty_mode_ioctl+0x573/0x670 drivers/tty/tty_ioctl.c:725
 n_tty_ioctl_helper+0x8b/0x4c0 drivers/tty/tty_ioctl.c:883
 n_tty_ioctl+0x102/0x200 drivers/tty/n_tty.c:2487
 tty_ioctl+0xa8f/0x1120 drivers/tty/tty_io.c:2814
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88816a96d527 of 1 bytes by task 31126 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1934 [inline]
 n_tty_poll+0x25e/0x4a0 drivers/tty/n_tty.c:2434
 tty_poll+0xa7/0x140 drivers/tty/tty_io.c:2231
 vfs_poll include/linux/poll.h:90 [inline]
 __io_arm_poll_handler+0x195/0x460 fs/io_uring.c:5158
 io_poll_add+0x68/0x510 fs/io_uring.c:5445
 io_issue_sqe+0xcd0/0x69f0 fs/io_uring.c:6193
 __io_queue_sqe+0xe7/0x360 fs/io_uring.c:6470
 io_queue_sqe fs/io_uring.c:6513 [inline]
 io_submit_sqe+0x1695/0x3400 fs/io_uring.c:6668
 io_submit_sqes+0x822/0xe50 fs/io_uring.c:6784
 __do_sys_io_uring_enter fs/io_uring.c:9395 [inline]
 __se_sys_io_uring_enter+0x1c9/0x9e0 fs/io_uring.c:9338
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9338
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x01 -> 0xcc

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31126 Comm: syz-executor.0 Tainted: G        W         5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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