[PATCH 4.19 39/58] usb: udc: core: Use lock when write to soft_connect

[Greg Kroah-Hartman]

From: Thinh Nguyen <thinh.ngu...@synopsys.com>

commit c28095bc99073ddda65e4f31f6ae0d908d4d5cd8 upstream.

Use lock to guard against concurrent access for soft-connect/disconnect
operations when writing to soft_connect sysfs.

Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
Cc: sta...@vger.kernel.org
Acked-by: Felipe Balbi <ba...@kernel.org>
Signed-off-by: Thinh Nguyen <thinh.ngu...@synopsys.com>
Link: 
https://lore.kernel.org/r/338ea01fbd69b1985ef58f0f59af02c805ddf189.1610611437.git.thinh.ngu...@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/usb/gadget/udc/core.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1471,10 +1471,13 @@ static ssize_t soft_connect_store(struct
                struct device_attribute *attr, const char *buf, size_t n)
 {
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev);
+       ssize_t                 ret;
 
+       mutex_lock(&udc_lock);
        if (!udc->driver) {
                dev_err(dev, "soft-connect without a gadget driver\n");
-               return -EOPNOTSUPP;
+               ret = -EOPNOTSUPP;
+               goto out;
        }
 
        if (sysfs_streq(buf, "connect")) {
@@ -1486,10 +1489,14 @@ static ssize_t soft_connect_store(struct
                usb_gadget_udc_stop(udc);
        } else {
                dev_err(dev, "unsupported command '%s'\n", buf);
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out;
        }
 
-       return n;
+       ret = n;
+out:
+       mutex_unlock(&udc_lock);
+       return ret;
 }
 static DEVICE_ATTR_WO(soft_connect);