[PATCH] usbip: vudc: Don't enable IRQs prematurely

[PATCH] usbip: vudc: Don't enable IRQs prematurely

[Dan Carpenter]

This code does:

	spin_unlock_irq(&udc->ud.lock);
	spin_unlock_irqrestore(&udc->lock, flags);

which does not make sense.  In theory, the first unlock could enable
IRQs and then the second _irqrestore could disable them again.  There
would be a brief momemt where IRQs were enabled improperly.

In real life, however, this function is always called with IRQs enabled
and the bug does not affect runtime.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
An alternative fix would be to make changes below and also change the
outside _irqsave/_irqrestore() to just _irq().  However, that's more
invasive and riskier with no upside.

 drivers/usb/usbip/vudc_sysfs.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
index d1cf6b51bf85..c95e6b2bfd32 100644
--- a/drivers/usb/usbip/vudc_sysfs.c
+++ b/drivers/usb/usbip/vudc_sysfs.c
@@ -128,7 +128,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 			goto unlock;
 		}
 
-		spin_lock_irq(&udc->ud.lock);
+		spin_lock(&udc->ud.lock);
 
 		if (udc->ud.status != SDEV_ST_AVAILABLE) {
 			ret = -EINVAL;
@@ -150,7 +150,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 		}
 
 		/* unlock and create threads and get tasks */
-		spin_unlock_irq(&udc->ud.lock);
+		spin_unlock(&udc->ud.lock);
 		spin_unlock_irqrestore(&udc->lock, flags);
 
 		tcp_rx = kthread_create(&v_rx_loop, &udc->ud, "vudc_rx");
@@ -173,14 +173,14 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 
 		/* lock and update udc->ud state */
 		spin_lock_irqsave(&udc->lock, flags);
-		spin_lock_irq(&udc->ud.lock);
+		spin_lock(&udc->ud.lock);
 
 		udc->ud.tcp_socket = socket;
 		udc->ud.tcp_rx = tcp_rx;
 		udc->ud.tcp_tx = tcp_tx;
 		udc->ud.status = SDEV_ST_USED;
 
-		spin_unlock_irq(&udc->ud.lock);
+		spin_unlock(&udc->ud.lock);
 
 		ktime_get_ts64(&udc->start_time);
 		v_start_timer(udc);
@@ -201,12 +201,12 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 			goto unlock;
 		}
 
-		spin_lock_irq(&udc->ud.lock);
+		spin_lock(&udc->ud.lock);
 		if (udc->ud.status != SDEV_ST_USED) {
 			ret = -EINVAL;
 			goto unlock_ud;
 		}
-		spin_unlock_irq(&udc->ud.lock);
+		spin_unlock(&udc->ud.lock);
 
 		usbip_event_add(&udc->ud, VUDC_EVENT_DOWN);
 	}
@@ -219,7 +219,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 sock_err:
 	sockfd_put(socket);
 unlock_ud:
-	spin_unlock_irq(&udc->ud.lock);
+	spin_unlock(&udc->ud.lock);
 unlock:
 	spin_unlock_irqrestore(&udc->lock, flags);
 	mutex_unlock(&udc->ud.sysfs_lock);
-- 
2.35.1

Re: [PATCH] usbip: vudc: Don't enable IRQs prematurely

[Shuah Khan]

On 5/25/22 6:30 AM, Dan Carpenter wrote:
> This code does:
> 
> 	spin_unlock_irq(&udc->ud.lock);
> 	spin_unlock_irqrestore(&udc->lock, flags);
> 
> which does not make sense.  In theory, the first unlock could enable
> IRQs and then the second _irqrestore could disable them again.  There
> would be a brief momemt where IRQs were enabled improperly.
> 
> In real life, however, this function is always called with IRQs enabled
> and the bug does not affect runtime.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> An alternative fix would be to make changes below and also change the
> outside _irqsave/_irqrestore() to just _irq().  However, that's more
> invasive and riskier with no upside.
> 

Thank you for the patch.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

Greg, please pick this up.

thanks,
-- Shuah