usb: usbtmc: Fix erroneous wait_srq ioctl return

wait_event_interruptible_timeout returns a long
The return was being assigned to an int causing an integer overflow when
the remaining jiffies > INT_MAX resulting in random error returns.

Use a long return value,  converting to the int ioctl return only on
error.

Fixes: 739240a ("usb: usbtmc: Add ioctl USBTMC488_IOCTL_WAIT_SRQ")
Cc: stable@vger.kernel.org
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250502070941.31819-3-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: dpenkler

drivers/usb/class/usbtmc.c

@@ -606,9 +606,9 @@ static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
 {
 	struct usbtmc_device_data *data = file_data->data;
 	struct device *dev = &data->intf->dev;
-	int rv;
 	u32 timeout;
 	unsigned long expire;
+	long wait_rv;
 
 	if (!data->iin_ep_present) {
 		dev_dbg(dev, "no interrupt endpoint present\n");
@@ -622,25 +622,24 @@ static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
 
 	mutex_unlock(&data->io_mutex);
 
-	rv = wait_event_interruptible_timeout(
-			data->waitq,
-			atomic_read(&file_data->srq_asserted) != 0 ||
-			atomic_read(&file_data->closing),
-			expire);
+	wait_rv = wait_event_interruptible_timeout(
+		data->waitq,
+		atomic_read(&file_data->srq_asserted) != 0 ||
+		atomic_read(&file_data->closing),
+		expire);
 
 	mutex_lock(&data->io_mutex);
 
 	/* Note! disconnect or close could be called in the meantime */
 	if (atomic_read(&file_data->closing) || data->zombie)
-		rv = -ENODEV;
+		return -ENODEV;
 
-	if (rv < 0) {
-		/* dev can be invalid now! */
-		pr_debug("%s - wait interrupted %d\n", __func__, rv);
-		return rv;
+	if (wait_rv < 0) {
+		dev_dbg(dev, "%s - wait interrupted %ld\n", __func__, wait_rv);
+		return wait_rv;
 	}
 
-	if (rv == 0) {
+	if (wait_rv == 0) {
 		dev_dbg(dev, "%s - wait timed out\n", __func__);
 		return -ETIMEDOUT;
 	}