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BUG: KCSAN: data-race in rxrpc_send_data / rxrpc_send_data_packet

write to 0xffff88811b562000 of 8 bytes by task 12837 on cpu 0:
 rxrpc_alloc_txqueue net/rxrpc/sendmsg.c:-1 [inline]
 rxrpc_send_data+0x8da/0x1550 net/rxrpc/sendmsg.c:398
 rxrpc_do_sendmsg+0xd72/0xe20 net/rxrpc/sendmsg.c:771
 rxrpc_sendmsg+0x47c/0x590 net/rxrpc/af_rxrpc.c:598
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x5af/0x600 net/socket.c:2592
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b562000 of 8 bytes by task 12871 on cpu 1:
 rxrpc_prepare_data_packet net/rxrpc/output.c:566 [inline]
 rxrpc_send_data_packet+0x465/0x1df0 net/rxrpc/output.c:664
 rxrpc_transmit_fresh_data net/rxrpc/call_event.c:255 [inline]
 rxrpc_transmit_some_data+0x69d/0x910 net/rxrpc/call_event.c:277
 rxrpc_input_call_event+0x8b7/0xf20 net/rxrpc/call_event.c:401
 rxrpc_io_thread+0x1e35/0x23c0 net/rxrpc/io_thread.c:550
 kthread+0x22a/0x280 kernel/kthread.c:467
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000000000000 -> 0xffff88811b561000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12871 Comm: krxrpcio/0 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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