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BUG: KCSAN: data-race in snd_rawmidi_poll / snd_rawmidi_receive

write to 0xffff8880b5995c38 of 8 bytes by task 11773 on cpu 0:
 snd_rawmidi_receive+0x1a3/0x4c0 sound/core/rawmidi.c:911
 snd_virmidi_dev_receive_event sound/core/seq/seq_virmidi.c:87 [inline]
 snd_virmidi_event_input sound/core/seq/seq_virmidi.c:109 [inline]
 snd_virmidi_event_input+0x1e3/0x270 sound/core/seq/seq_virmidi.c:101
 snd_seq_deliver_single_event.constprop.0+0x3e8/0x4d0 sound/core/seq/seq_clientmgr.c:638
 snd_seq_deliver_event+0x2e9/0x4c0 sound/core/seq/seq_clientmgr.c:839
 snd_seq_kernel_client_dispatch+0xef/0x110 sound/core/seq/seq_clientmgr.c:2323
 snd_seq_oss_dispatch sound/core/seq/oss/seq_oss_device.h:138 [inline]
 snd_seq_oss_midi_reset+0x1ff/0x2e0 sound/core/seq/oss/seq_oss_midi.c:470
 snd_seq_oss_synth_reset+0x2b1/0x4c0 sound/core/seq/oss/seq_oss_synth.c:404
 snd_seq_oss_reset+0x4f/0x170 sound/core/seq/oss/seq_oss_init.c:435
 snd_seq_oss_release+0x6e/0xf0 sound/core/seq/oss/seq_oss_init.c:412
 odev_release+0x49/0x70 sound/core/seq/oss/seq_oss.c:140
 __fput+0x1e1/0x520 fs/file_table.c:280
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b5995c38 of 8 bytes by task 11749 on cpu 1:
 snd_rawmidi_ready sound/core/rawmidi.c:79 [inline]
 snd_rawmidi_poll+0x1a1/0x310 sound/core/rawmidi.c:1405
 vfs_poll include/linux/poll.h:90 [inline]
 do_select+0x7d0/0x1020 fs/select.c:534
 core_sys_select+0x381/0x550 fs/select.c:677
 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
 __do_sys_pselect6 fs/select.c:784 [inline]
 __se_sys_pselect6 fs/select.c:769 [inline]
 __x64_sys_pselect6+0x12e/0x170 fs/select.c:769
 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: 1 PID: 11749 Comm: syz-executor.4 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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