Re: [PATCH 7/7] [v5] drivers/virt: introduce Freescale hypervisor management driver

Hi Timur, thanks for addressing the issues I pointed out. Unfortunately, I
have found a few more now:

On Thursday 09 June 2011 21:13:14 Timur Tabi wrote:

+       /* Make sure the application is called the right driver. */
+       if (_IOC_TYPE(cmd) != 0) {
+               pr_debug("fsl-hv: ioctl type %u should be 0\n", _IOC_TYPE(cmd));
+               return -EINVAL;
+       }
+
+       /* Make sure the application set the direction flag correctly. */
+       if (_IOC_DIR(cmd) != (_IOC_READ | _IOC_WRITE)) {
+               pr_debug("fsl-hv: ioctl direction should be _IOWR\n");
+               return -EINVAL;
+       }
+
+       /*
+        * Make sure the application is passing the right structure to us.
+        * For backwards compatibility with older applications, we only check
+        * if the size is too small, rather than unequal.
+        */
+
+       switch (_IOC_NR(cmd)) {
+       case (_IOC_NR(FSL_HV_IOCTL_PARTITION_RESTART)):
+               size = sizeof(struct fsl_hv_ioctl_restart);
+               if (_IOC_SIZE(cmd) < size)
+                       goto size_error;
+               ret = ioctl_restart(arg);
+               break;

As mentioned, it would be easier and more readable to just do

	switch(cmd) {
	case FSL_HV_IOCTL_PARTITION_RESTART:
		...

	case FSL_HV_IOCTL_PARTITION_GET_STATUS;
		...

There is no need to check the bits individually when you can simply
compare the command number.

+/**
+ * enum fsl_hv_ioctl_cmd - ioctl commands
+ * @FSL_HV_IOCTL_PARTITION_RESTART: restart another partition
+ * @FSL_HV_IOCTL_PARTITION_GET_STATUS: get a partition's status
+ * @FSL_HV_IOCTL_PARTITION_START: boot another partition
+ * @FSL_HV_IOCTL_PARTITION_STOP: stop this or another partition
+ * @FSL_HV_IOCTL_MEMCPY: copy data from one partition to another
+ * @FSL_HV_IOCTL_DOORBELL: ring a doorbell
+ * @FSL_HV_IOCTL_GETPROP: get a property from another guest's device tree
+ * @FSL_HV_IOCTL_SETPROP: set a property in another guest's device tree
+ *
+ * This enum lists the available ioctl commands for the Freescale hypervisor
+ * management driver.  The meaning
+ */
+enum fsl_hv_ioctl_cmd {
+       FSL_HV_IOCTL_PARTITION_RESTART = _IOWR(0, 1, struct fsl_hv_ioctl_restart),
+       FSL_HV_IOCTL_PARTITION_GET_STATUS = _IOWR(0, 2, struct fsl_hv_ioctl_status),
+       FSL_HV_IOCTL_PARTITION_START = _IOWR(0, 3, struct fsl_hv_ioctl_start),
+       FSL_HV_IOCTL_PARTITION_STOP = _IOWR(0, 4, struct fsl_hv_ioctl_stop),
+       FSL_HV_IOCTL_MEMCPY = _IOWR(0, 5, struct fsl_hv_ioctl_memcpy),
+       FSL_HV_IOCTL_DOORBELL = _IOWR(0, 6, struct fsl_hv_ioctl_doorbell),
+       FSL_HV_IOCTL_GETPROP = _IOWR(0, 7, struct fsl_hv_ioctl_prop),
+       FSL_HV_IOCTL_SETPROP = _IOWR(0, 8, struct fsl_hv_ioctl_prop),
+};

Using a #define here is usually preferred because then you can use #ifdef in a user
application to check if a given value has been assigned.

More importantly, the code you have chose (0) conflicts with existing drivers
(frame buffer, scsi and wavefront among others). Please chose a free one and
add it to Documentation/ioctl/ioctl-number.txt in the same patch.

	Arnd