FAILED: patch "[PATCH] usb: udc: core: Use lock when write to soft_connect" failed to apply to 4.4-stable tree

gregkh
2021-01-26T04:39:34Z

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c28095bc99073ddda65e4f31f6ae0d908d4d5cd8 Mon Sep 17 00:00:00 2001
From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Date: Thu, 14 Jan 2021 00:09:51 -0800
Subject: [PATCH] usb: udc: core: Use lock when write to soft_connect

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: stable@vger.kernel.org
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/338ea01fbd69b1985ef58f0f59af02c805ddf189.1610611437.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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);