==================================================================
BUG: KCSAN: data-race in __snd_rawmidi_transmit_ack / snd_rawmidi_drain_output

write to 0xffff88810031f3c8 of 1 bytes by task 10342 on cpu 1:
 snd_rawmidi_drain_output+0x5f/0x310 sound/core/rawmidi.c:210
 close_substream.part.0+0x1f6/0x2f0 sound/core/rawmidi.c:499
 close_substream sound/core/rawmidi.c:485 [inline]
 rawmidi_release_priv+0x11a/0x180 sound/core/rawmidi.c:525
 snd_rawmidi_release+0x3f/0x90 sound/core/rawmidi.c:556
 __fput+0x1c3/0x4f0 fs/file_table.c:280
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810031f3c8 of 1 bytes by task 2522 on cpu 0:
 __snd_rawmidi_transmit_ack+0x10a/0x1c0 sound/core/rawmidi.c:1237
 snd_rawmidi_transmit+0x91/0xc0 sound/core/rawmidi.c:1293
 snd_vmidi_output_work+0xaf/0x1f0 sound/core/seq/seq_virmidi.c:143
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2522 Comm: kworker/0:1H Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_highpri snd_vmidi_output_work
==================================================================