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BUG: KCSAN: data-race in __skb_wait_for_more_packets / l2cap_sock_shutdown

write to 0xffff888124407e6a of 1 bytes by task 29786 on cpu 1:
 l2cap_sock_shutdown+0x1ae/0x680 net/bluetooth/l2cap_sock.c:1147
 __sys_shutdown+0xa2/0x130 net/socket.c:2160
 __do_sys_shutdown net/socket.c:2168 [inline]
 __se_sys_shutdown net/socket.c:2166 [inline]
 __x64_sys_shutdown+0x3a/0x50 net/socket.c:2166
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888124407e6a of 1 bytes by task 29789 on cpu 0:
 __skb_wait_for_more_packets+0x17e/0x330 net/core/datagram.c:104
 __skb_recv_datagram+0xf0/0x160 net/core/datagram.c:310
 skb_recv_datagram+0x76/0xb0 net/core/datagram.c:321
 bt_sock_recvmsg+0x7e/0x3f0 net/bluetooth/af_bluetooth.c:266
 l2cap_sock_recvmsg+0xc9/0x370 net/bluetooth/l2cap_sock.c:1013
 sock_recvmsg_nosec net/socket.c:871 [inline]
 sock_recvmsg net/socket.c:889 [inline]
 sock_recvmsg+0x92/0xb0 net/socket.c:885
 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480
 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601
 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680
 __do_sys_recvmmsg net/socket.c:2703 [inline]
 __se_sys_recvmmsg net/socket.c:2696 [inline]
 __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 29789 Comm: syz-executor.3 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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