[PATCH v3] usb: udc: core: Use lock when write to soft_connect

From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
To: Felipe Balbi <balbi@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, Peter Chen <peter.chen@nxp.com>,
	Lee Jones <lee.jones@linaro.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Dejin Zheng <zhengdejin5@gmail.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	"Ahmed S. Darwish" <a.darwish@linutronix.de>,
	Michal Nazarewicz <mina86@mina86.com>
Cc: stable@vger.kernel.org
Subject: [PATCH v3] usb: udc: core: Use lock when write to soft_connect
Date: Thu, 14 Jan 2021 00:09:51 -0800	[thread overview]
Message-ID: <338ea01fbd69b1985ef58f0f59af02c805ddf189.1610611437.git.Thinh.Nguyen@synopsys.com> (raw)

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

Cc: stable@vger.kernel.org
Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 Changes in v3:
 - Improve flow: avoid assigning "ret = n" early
 Changes in v2:
 - Consolidate mutex_unlock to a single place using "goto out"

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

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 6a62bbd01324..ea114f922ccf 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1529,10 +1529,13 @@ static ssize_t soft_connect_store(struct device *dev,
 		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")) {
@@ -1543,10 +1546,14 @@ static ssize_t soft_connect_store(struct device *dev,
 		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);
 

base-commit: 4e0dcf62ab4cf917d0cbe751b8bf229a065248d4
-- 
2.28.0

