Am Donnerstag, den 17.05.2018, 19:03 +0200 schrieb Guido Kiener:
> +static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
> + unsigned int __user *arg)
> +{
> + struct usbtmc_device_data *data = file_data->data;
> + struct device *dev = &data->intf->dev;
> + int rv;
> + unsigned int timeout;
> + unsigned long expire;
> +
> + if (!data->iin_ep_present) {
> + dev_dbg(dev, "no interrupt endpoint present\n");
> + return -EFAULT;
> + }
> +
> + if (get_user(timeout, arg))
> + return -EFAULT;
> +
> + expire = msecs_to_jiffies(timeout);
> +
> + mutex_unlock(&data->io_mutex);
There is such a thing as threads sharing file descriptors.
That leads to the question what happens to the mutex if this
ioctl() is called multiple times.
Regards
Oliver
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