Op 02-02-16 om 21:28 schreef Gustavo Padovan:
Hi Maarten,
2016-02-02 Maarten Lankhorst maarten.lankhorst@linux.intel.com:
Op 02-02-16 om 14:23 schreef Gustavo Padovan:
From: Gustavo Padovan gustavo.padovan@collabora.co.uk
Making fence_info a pointer enables us to extend the struct in the future without breaking the ABI.
v2: use type __u64 for fence_info Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.co.uk
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 f7530f0..03b1214 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 ed281fc..8e2ed32 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 fence_info[0];
- __u64 fence_info;
With the information from the commit I would expect fence_info would be a true pointer.
I missed that. It is fixed for v3 now.
so if (sync_file_info->num_fences == 0) not copying fence_info, but set all members including this one. else for_all_fences() copy_to_user(fence_info struct)
Otherwise you still can't extend the struct without breaking the abi.
all sync_files have at least 1 fence so we are left to the else case, coupy all fences to the user. So we always have variable length at the end of the struct. But I still don't see how this will prevent us from breaking the API.
Ok this was with fence_info not being a pointer. :)