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BUG: KCSAN: data-race in snd_seq_oss_midi_input / snd_seq_oss_timer_stop

write to 0xffff888014f79c90 of 4 bytes by task 15227 on cpu 1:
 snd_seq_oss_timer_stop+0xbc/0xf0 sound/core/seq/oss/seq_oss_timer.c:177
 snd_seq_oss_reset+0x14d/0x160 sound/core/seq/oss/seq_oss_init.c:450
 snd_seq_oss_release+0x76/0x170 sound/core/seq/oss/seq_oss_init.c:412
 odev_release+0x3a/0x60 sound/core/seq/oss/seq_oss.c:140
 __fput+0x263/0x4f0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x17c/0x1b0 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888014f79c90 of 4 bytes by task 15187 on cpu 0:
 send_midi_event sound/core/seq/oss/seq_oss_midi.c:601 [inline]
 snd_seq_oss_midi_input+0x2bb/0x500 sound/core/seq/oss/seq_oss_midi.c:524
 snd_seq_oss_event_input+0xbc/0x100 sound/core/seq/oss/seq_oss_event.c:429
 snd_seq_deliver_single_event+0x31e/0x4f0 sound/core/seq/seq_clientmgr.c:637
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:692 [inline]
 snd_seq_deliver_event+0x38d/0x4a0 sound/core/seq/seq_clientmgr.c:827
 snd_seq_kernel_client_dispatch+0x16f/0x190 sound/core/seq/seq_clientmgr.c:2322
 snd_vmidi_output_work+0x16d/0x200 sound/core/seq/seq_virmidi.c:150
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15187 Comm: kworker/0:2H Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_highpri snd_vmidi_output_work
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