On 1 March 2016 at 13:13, Gustavo Padovan <gustavo@xxxxxxxxxxx> wrote:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
>
> Play safe and add flags member to all structs. So we don't need to
> break API or create new IOCTL in the future if new features that requires
> flags arises.
>
> v2: check if flags are valid (zero, in this case)
>
> v3: return -EINVAL if flags are not zero'ed
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> ---
> drivers/staging/android/sync.c | 8 ++++++++
> drivers/staging/android/uapi/sync.h | 6 ++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
> index 3604e453..3c265ed 100644
> --- a/drivers/staging/android/sync.c
> +++ b/drivers/staging/android/sync.c
> @@ -445,6 +445,11 @@ static long sync_file_ioctl_merge(struct sync_file *sync_file,
> goto err_put_fd;
> }
>
> + if (data.flags) {
> + err = -EINVAL;
> + goto err_put_fd;
> + }
> +
> fence2 = sync_file_fdget(data.fd2);
> if (!fence2) {
> err = -ENOENT;
> @@ -504,6 +509,9 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> if (copy_from_user(&in, (void __user *)arg, sizeof(in)))
> return -EFAULT;
>
> + if (in.flags)
> + return -EINVAL;
> +
> info = kzalloc(sizeof(*info), GFP_KERNEL);
> if (!info)
> return -ENOMEM;
> diff --git a/drivers/staging/android/uapi/sync.h b/drivers/staging/android/uapi/sync.h
> index a122bb5..11e2d28 100644
> --- a/drivers/staging/android/uapi/sync.h
> +++ b/drivers/staging/android/uapi/sync.h
> @@ -19,11 +19,13 @@
> * @fd2: file descriptor of second fence
> * @name: name of new fence
> * @fence: returns the fd of the new fence to userspace
> + * @flags: merge_data flags
> */
> struct sync_merge_data {
> __s32 fd2;
> char name[32];
> __s32 fence;
> + __u32 flags;
The comment from last round still stands, struct size must be multiple
of 64bits. As is the struct will be broken whenever/if we decide to
extend it. See [1] for an alternative wording.
> };
>
> /**
> @@ -31,12 +33,14 @@ struct sync_merge_data {
> * @obj_name: name of parent sync_timeline
> * @driver_name: name of driver implementing the parent
> * @status: status of the fence 0:active 1:signaled <0:error
> + * @flags: fence_info flags
> * @timestamp_ns: timestamp of status change in nanoseconds
> */
> struct sync_fence_info {
> char obj_name[32];
> char driver_name[32];
> __s32 status;
> + __u32 flags;
> __u64 timestamp_ns;
> };
>
> @@ -44,6 +48,7 @@ struct sync_fence_info {
> * struct sync_file_info - data returned from fence info ioctl
> * @name: name of fence
> * @status: status of fence. 1: signaled 0:active <0:error
> + * @flags: sync_file_info flags
> * @num_fences number of fences in the sync_file
> * @sync_fence_info: pointer to array of structs sync_fence_info with all
> * fences in the sync_file
> @@ -51,6 +56,7 @@ struct sync_fence_info {
> struct sync_file_info {
> char name[32];
> __s32 status;
> + __u32 flags;
> __u32 num_fences;
>
> __u64 sync_fence_info;
Thanks for taking my suggestion and dropping len. Although I fear that
we introduced a hole which we should be explicitly padded [2].
In both cases the pad should be checked for 0 and -EINVAL should be
returned if that's not the case. This will allow us to potentially
reuse in the future.
Other than that I believe the series looks pretty much spot on.
Cheers,
Emil
[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n37
[2] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n32
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