syzbot

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BUG: KCSAN: data-race in tty_send_xchar / tty_send_xchar

write to 0xffff88811b58e5bc of 1 bytes by task 2639 on cpu 0:
 __stop_tty drivers/tty/tty_io.c:768 [inline]
 stop_tty drivers/tty/tty_io.c:794 [inline]
 tty_send_xchar+0x1db/0x290 drivers/tty/tty_io.c:1184
 n_tty_ioctl_helper+0x2d8/0x450
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2421
 tty_ioctl+0xaf5/0x1130 drivers/tty/tty_io.c:2814
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88811b58e5bc of 1 bytes by task 2643 on cpu 1:
 tty_send_xchar+0x44/0x290 drivers/tty/tty_io.c:1167
 n_tty_ioctl_helper+0x2d8/0x450
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2421
 tty_ioctl+0xaf5/0x1130 drivers/tty/tty_io.c:2814
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2643 Comm: syz-executor.3 Not tainted 5.16.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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