From:   jassisinghbrar@gmail.com
To:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     gregkh@linuxfoundation.org, error27@gmail.com,
        stern@rowland.harvard.edu, Jassi Brar <jaswinder.singh@linaro.org>
Subject: [PATCH] usb: gadget: udc: max3420_udc: fix serialized access
Date:   Wed,  8 Feb 2023 10:34:18 -0600
Message-Id: <20230208163418.342210-1-jassisinghbrar@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Jassi Brar <jaswinder.singh@linaro.org>

 The mutex 'spi_bus_mutex' should be used, instead of the spin-lock,
while changing the state of the kernel-thread. Also changing the
usb-gadget state need not be protected by a spin-lock.
 This should fix the Smatch static checker warning
    warn: sleeping in atomic context

Fixes: 48ba02b2e2b1 ("usb: gadget: add udc driver for max3420")
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
---
 drivers/usb/gadget/udc/max3420_udc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/max3420_udc.c b/drivers/usb/gadget/udc/max3420_udc.c
index ddf0ed3eb4f2..3666cc44f4e7 100644
--- a/drivers/usb/gadget/udc/max3420_udc.c
+++ b/drivers/usb/gadget/udc/max3420_udc.c
@@ -501,13 +501,16 @@ static irqreturn_t max3420_vbus_handler(int irq, void *dev_id)
 	unsigned long flags;
 
 	spin_lock_irqsave(&udc->lock, flags);
+
 	/* its a vbus change interrupt */
 	udc->vbus_active = !udc->vbus_active;
 	udc->todo |= UDC_START;
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+
 	usb_udc_vbus_handler(&udc->gadget, udc->vbus_active);
 	usb_gadget_set_state(&udc->gadget, udc->vbus_active
 			     ? USB_STATE_POWERED : USB_STATE_NOTATTACHED);
-	spin_unlock_irqrestore(&udc->lock, flags);
 
 	if (udc->thread_task)
 		wake_up_process(udc->thread_task);
@@ -1298,15 +1301,14 @@ static int max3420_probe(struct spi_device *spi)
 static void max3420_remove(struct spi_device *spi)
 {
 	struct max3420_udc *udc = spi_get_drvdata(spi);
-	unsigned long flags;
 
 	usb_del_gadget_udc(&udc->gadget);
 
-	spin_lock_irqsave(&udc->lock, flags);
+	mutex_lock(&udc->spi_bus_mutex);
 
 	kthread_stop(udc->thread_task);
 
-	spin_unlock_irqrestore(&udc->lock, flags);
+	mutex_unlock(&udc->spi_bus_mutex);
 }
 
 static const struct of_device_id max3420_udc_of_match[] = {
-- 
2.34.1