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usb: gadget: function: printer: avoid spinlock recursion

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If usb_gadget_giveback_request() is called in usb_ep_queue(),
this printer_write() is possible to cause spinlock recursion. So,
this patch adds spin_unlock() before calls usb_ep_queue() to avoid it.

Signed-off-by: Yoshihiro Shimoda <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>
This commit is contained in:
Yoshihiro Shimoda 2017-09-13 15:31:33 +09:00 • committed by Felipe Balbi
commit 9ada8c5820
1 changed files with 6 additions and 1 deletions
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7
drivers/usb/gadget/function/f_printer.c
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@ -555,6 +555,7 @@ printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
size_t size; /* Amount of data in a TX request. */
size_t bytes_copied = 0;
struct usb_request *req;
int value;
DBG(dev, "printer_write trying to send %d bytes\n", (int)len);
@ -634,7 +635,11 @@ printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
return -EAGAIN;
}
if (usb_ep_queue(dev->in_ep, req, GFP_ATOMIC)) {
/* here, we unlock, and only unlock, to avoid deadlock. */
spin_unlock(&dev->lock);
value = usb_ep_queue(dev->in_ep, req, GFP_ATOMIC);
spin_lock(&dev->lock);
if (value) {
list_add(&req->list, &dev->tx_reqs);
spin_unlock_irqrestore(&dev->lock, flags);
mutex_unlock(&dev->lock_printer_io);