syzbot

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BUG: KCSAN: data-race in tty_port_block_til_ready / tty_set_termios

write to 0xffff8881281dd110 of 4 bytes by task 22865 on cpu 0:
 tty_set_termios+0x780/0x8a0 drivers/tty/tty_ioctl.c:351
 set_termios+0x47e/0x4c0 drivers/tty/tty_ioctl.c:524
 tty_mode_ioctl+0x3e1/0x590
 n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:992
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2516
 tty_ioctl+0x875/0xbc0 drivers/tty/tty_io.c:2785
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881281dd110 of 4 bytes by task 22862 on cpu 1:
 tty_port_block_til_ready+0xe9/0x4e0 drivers/tty/tty_port.c:530
 tty_port_open+0x1ac/0x1f0 drivers/tty/tty_port.c:792
 uart_open+0x30/0x40 drivers/tty/serial/serial_core.c:1940
 tty_open+0x3d3/0xb00 drivers/tty/tty_io.c:2144
 chrdev_open+0x34f/0x3c0 fs/char_dev.c:414
 do_dentry_open+0x5c3/0xae0 fs/open.c:929
 vfs_open+0x4a/0x50 fs/open.c:1063
 do_open fs/namei.c:3639 [inline]
 path_openat+0x17f2/0x1d10 fs/namei.c:3796
 do_filp_open+0xf6/0x200 fs/namei.c:3823
 do_sys_openat2+0xab/0x110 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000006 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22862 Comm: syz-executor.0 Not tainted 6.6.0-rc2-syzkaller-00337-gd90b0276af8f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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