[PATCH v4] usb: gadget: function: fix missing spinlock in f_uac1_legacy

[qiang.zhang]

From: Zhang Qiang <qiang.zh...@windriver.com>

Add a missing spinlock protection for play_queue, because
the play_queue may be destroyed when the "playback_work"
work func and "f_audio_out_ep_complete" callback func
operate this paly_queue at the same time.

Fixes: c6994e6f067cf ("USB: gadget: add USB Audio Gadget driver")
Cc: stable <sta...@vger.kernel.org>
Signed-off-by: Zhang Qiang <qiang.zh...@windriver.com>
---
 v1->v2->v3->v4:
 Add changelog text and Cc tags, Fixes tags.

 drivers/usb/gadget/function/f_uac1_legacy.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/gadget/function/f_uac1_legacy.c 
b/drivers/usb/gadget/function/f_uac1_legacy.c
index 349deae7cabd..e2d7f69128a0 100644
--- a/drivers/usb/gadget/function/f_uac1_legacy.c
+++ b/drivers/usb/gadget/function/f_uac1_legacy.c
@@ -336,7 +336,9 @@ static int f_audio_out_ep_complete(struct usb_ep *ep, 
struct usb_request *req)
 
        /* Copy buffer is full, add it to the play_queue */
        if (audio_buf_size - copy_buf->actual < req->actual) {
+               spin_lock_irq(&audio->lock);
                list_add_tail(&copy_buf->list, &audio->play_queue);
+               spin_unlock_irq(&audio->lock);
                schedule_work(&audio->playback_work);
                copy_buf = f_audio_buffer_alloc(audio_buf_size);
                if (IS_ERR(copy_buf))
-- 
2.24.1