Op 03-02-16 om 14:25 schreef Gustavo Padovan:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
>
> Turn sync_fence_info into __u64 type enable us to extend the struct in the
> future without breaking the ABI.
>
> v2: use type __u64 for fence_info
>
> v3: fix commit message to reflect the v2 change
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> ---
> drivers/staging/android/sync.c | 2 +-
> drivers/staging/android/uapi/sync.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
> index 2ab0c20..8425457 100644
> --- a/drivers/staging/android/sync.c
> +++ b/drivers/staging/android/sync.c
> @@ -525,7 +525,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> if (info->status >= 0)
> info->status = !info->status;
>
> - len = sizeof(struct sync_file_info);
> + len = sizeof(struct sync_file_info) - sizeof(__u64);
>
> for (i = 0; i < sync_file->num_fences; ++i) {
> struct fence *fence = sync_file->cbs[i].fence;
> diff --git a/drivers/staging/android/uapi/sync.h b/drivers/staging/android/uapi/sync.h
> index a0cf357..e649953 100644
> --- a/drivers/staging/android/uapi/sync.h
> +++ b/drivers/staging/android/uapi/sync.h
> @@ -54,7 +54,7 @@ struct sync_file_info {
> char name[32];
> __s32 status;
>
> - __u8 sync_fence_info[0];
> + __u64 sync_fence_info;
> };
>
> #define SYNC_IOC_MAGIC '>'
This still doesn't do what you expect it to.
I think this is what you want is for userspace to do:
struct sync_file_info info;
info.flags = info.num_fences = 0;
ioctl(fd, SYNC_IOC_FENCE_INFO, &info);
if (info.num_fences) {
info.sync_fence_info = (uintptr)kcalloc(info.num_fences, sizeof(struct sync_fence_info));
ioctl(fd, SYNC_IOC_FENCE_INFO, &info);
}
Maybe userspace could preallocate the max in advance and set num_fences higher,
kernel would do something like:
num_fences = min(info.num_fences, sync->num_fences);
struct sync_fence_info array[num_fences];
info.num_fences = sync->num_fences;
if (num_fences &&
copy_to_user((void * __user)(unsigned long)info.sync_fence_info, array, num_fences * sizeof(array)))
return -EFAULT;
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