syzbot

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BUG: KCSAN: data-race in snd_seq_oss_readq_clear / snd_seq_oss_readq_put_timestamp

write to 0xffff888081e8d4a0 of 8 bytes by task 17166 on cpu 1:
 snd_seq_oss_readq_clear+0x81/0x90 sound/core/seq/oss/seq_oss_readq.c:82
 snd_seq_oss_reset+0x102/0x160 sound/core/seq/oss/seq_oss_init.c:445
 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+0x246/0x4d0 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0x1b2/0x210 kernel/entry/common.c:190
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:265
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888081e8d4a0 of 8 bytes by task 3256 on cpu 0:
 snd_seq_oss_readq_put_timestamp+0x28/0x2c0 sound/core/seq/oss/seq_oss_readq.c:218
 send_synth_event sound/core/seq/oss/seq_oss_midi.c:585 [inline]
 snd_seq_oss_midi_input+0x4d5/0x500 sound/core/seq/oss/seq_oss_midi.c:522
 snd_seq_oss_event_input+0xbc/0x100 sound/core/seq/oss/seq_oss_event.c:429
 snd_seq_deliver_single_event+0x31b/0x4f0 sound/core/seq/seq_clientmgr.c:638
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:693 [inline]
 snd_seq_deliver_event+0x392/0x4a0 sound/core/seq/seq_clientmgr.c:828
 snd_seq_kernel_client_dispatch+0x16f/0x190 sound/core/seq/seq_clientmgr.c:2323
 snd_vmidi_output_work+0x16d/0x200 sound/core/seq/seq_virmidi.c:150
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/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: 3256 Comm: kworker/0:1H Not tainted 5.9.0-rc3-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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