Hi Greg,
Any comments on this?
Thanks,
Gustavo
2016-03-18 Gustavo Padovan <gustavo at padovan.org>:
> From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>
> Change SYNC_IOC_FILE_INFO (former SYNC_IOC_FENCE_INFO) behaviour to avoid
> future API breaks and optimize buffer allocation.
>
> Now num_fences can be filled by the caller to inform how many fences it
> wants to retrieve from the kernel. If the num_fences passed is greater
> than zero info->sync_fence_info should point to a buffer with enough space
> to fit all fences.
>
> However if num_fences passed to the kernel is 0, the kernel will reply
> with number of fences of the sync_file.
>
> Sending first an ioctl with num_fences = 0 can optimize buffer allocation,
> in a first call with num_fences = 0 userspace will receive the actual
> number of fences in the num_fences filed.
>
> Then it can allocate a buffer with the correct size on sync_fence_info and
> call SYNC_IOC_FILE_INFO again, but now with the actual value of num_fences
> in the sync_file.
>
> info->sync_fence_info was converted to __u64 pointer to prevent 32bit
> compatibility issues. And a flags member was added.
>
> An example userspace code for the later would be:
>
> struct sync_file_info *info;
> int err, size, num_fences;
>
> info = malloc(sizeof(*info));
>
> info.flags = 0;
> err = ioctl(fd, SYNC_IOC_FILE_INFO, info);
> num_fences = info->num_fences;
>
> if (num_fences) {
> info.flags = 0;
> size = sizeof(struct sync_fence_info) * num_fences;
> info->num_fences = num_fences;
> info->sync_fence_info = (uint64_t) calloc(num_fences,
> sizeof(struct
> sync_fence_info));
>
> err = ioctl(fd, SYNC_IOC_FILE_INFO, info);
> }
>
> Finally the IOCTLs numbers were changed to avoid any potential old
> userspace running the old API to get weird errors. Changing the opcodes
> will make them fail right away. This is just a precaution, there no
> upstream users of these interfaces yet and the only user is Android, but
> we don't expect anyone trying to run android userspace and all it
> dependencies on top of upstream kernels.
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
> Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Acked-by: Greg Hackmann <ghackmann at google.com>
> Acked-by: Rob Clark <robdclark at gmail.com>
> Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>
> ---
> v2: fix fence_info memory leak
>
> v3: Comments from Emil Velikov
> - improve commit message
> - remove __u64 cast
> - remove check for output fields in file_info
> - clean up sync_fill_fence_info()
>
> Comments from Maarten Lankhorst
> - remove in.num_fences && !in.sync_fence_info check
> - remove info->len and use only num_fences to calculate size
>
> Comments from Dan Carpenter
> - fix info->sync_fence_info documentation
>
> v4: remove allocated struct sync_file_info (comment from Maarten)
>
> v5: merge all commits that were changing the ABI
>
> v6: fix -Wint-to-pointer-cast error on info.sync_fence_info
> ---
> drivers/staging/android/sync.c | 76
> ++++++++++++++++++++-----------------
> drivers/staging/android/uapi/sync.h | 36 +++++++++++++-----
> 2 files changed, 67 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
> index 3a8f210..f9c6094 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 || data.pad) {
> + err = -EINVAL;
> + goto err_put_fd;
> + }
> +
> fence2 = sync_file_fdget(data.fd2);
> if (!fence2) {
> err = -ENOENT;
> @@ -479,13 +484,9 @@ err_put_fd:
> return err;
> }
>
> -static int sync_fill_fence_info(struct fence *fence, void *data, int size)
> +static void sync_fill_fence_info(struct fence *fence,
> + struct sync_fence_info *info)
> {
> - struct sync_fence_info *info = data;
> -
> - if (size < sizeof(*info))
> - return -ENOMEM;
> -
> strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
> sizeof(info->obj_name));
> strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
> @@ -495,58 +496,63 @@ static int sync_fill_fence_info(struct fence *fence,
> void *data, int size)
> else
> info->status = 0;
> info->timestamp_ns = ktime_to_ns(fence->timestamp);
> -
> - return sizeof(*info);
> }
>
> static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> unsigned long arg)
> {
> - struct sync_file_info *info;
> + struct sync_file_info info;
> + struct sync_fence_info *fence_info = NULL;
> __u32 size;
> - __u32 len = 0;
> int ret, i;
>
> - if (copy_from_user(&size, (void __user *)arg, sizeof(size)))
> + if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
> return -EFAULT;
>
> - if (size < sizeof(struct sync_file_info))
> + if (info.flags || info.pad)
> return -EINVAL;
>
> - if (size > 4096)
> - size = 4096;
> -
> - info = kzalloc(size, GFP_KERNEL);
> - if (!info)
> - return -ENOMEM;
> -
> - strlcpy(info->name, sync_file->name, sizeof(info->name));
> - info->status = atomic_read(&sync_file->status);
> - if (info->status >= 0)
> - info->status = !info->status;
> -
> - len = sizeof(struct sync_file_info);
> + /*
> + * Passing num_fences = 0 means that userspace doesn't want to
> + * retrieve any sync_fence_info. If num_fences = 0 we skip filling
> + * sync_fence_info and return the actual number of fences on
> + * info->num_fences.
> + */
> + if (!info.num_fences)
> + goto no_fences;
>
> - for (i = 0; i < sync_file->num_fences; ++i) {
> - struct fence *fence = sync_file->cbs[i].fence;
> + if (info.num_fences < sync_file->num_fences)
> + return -EINVAL;
>
> - ret = sync_fill_fence_info(fence, (u8 *)info + len, size - len);
> + size = sync_file->num_fences * sizeof(*fence_info);
> + fence_info = kzalloc(size, GFP_KERNEL);
> + if (!fence_info)
> + return -ENOMEM;
>
> - if (ret < 0)
> - goto out;
> + for (i = 0; i < sync_file->num_fences; ++i)
> + sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
>
> - len += ret;
> + if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
> + size)) {
> + ret = -EFAULT;
> + goto out;
> }
>
> - info->len = len;
> +no_fences:
> + strlcpy(info.name, sync_file->name, sizeof(info.name));
> + info.status = atomic_read(&sync_file->status);
> + if (info.status >= 0)
> + info.status = !info.status;
> +
> + info.num_fences = sync_file->num_fences;
>
> - if (copy_to_user((void __user *)arg, info, len))
> + if (copy_to_user((void __user *)arg, &info, sizeof(info)))
> ret = -EFAULT;
> else
> ret = 0;
>
> out:
> - kfree(info);
> + kfree(fence_info);
>
> return ret;
> }
> @@ -560,7 +566,7 @@ static long sync_file_ioctl(struct file *file, unsigned
> int cmd,
> case SYNC_IOC_MERGE:
> return sync_file_ioctl_merge(sync_file, arg);
>
> - case SYNC_IOC_FENCE_INFO:
> + case SYNC_IOC_FILE_INFO:
> return sync_file_ioctl_fence_info(sync_file, arg);
>
> default:
> diff --git a/drivers/staging/android/uapi/sync.h
> b/drivers/staging/android/uapi/sync.h
> index 4467c76..fbadb8a 100644
> --- a/drivers/staging/android/uapi/sync.h
> +++ b/drivers/staging/android/uapi/sync.h
> @@ -16,14 +16,18 @@
>
> /**
> * struct sync_merge_data - data passed to merge ioctl
> - * @fd2: file descriptor of second fence
> * @name: name of new fence
> + * @fd2: file descriptor of second fence
> * @fence: returns the fd of the new fence to userspace
> + * @flags: merge_data flags
> + * @pad: padding for 64-bit alignment, should always be zero
> */
> struct sync_merge_data {
> - __s32 fd2;
> char name[32];
> + __s32 fd2;
> __s32 fence;
> + __u32 flags;
> + __u32 pad;
> };
>
> /**
> @@ -31,42 +35,54 @@ 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;
> };
>
> /**
> * struct sync_file_info - data returned from fence info ioctl
> - * @len: ioctl caller writes the size of the buffer its passing in.
> - * ioctl returns length of sync_file_info returned to
> - * userspace including pt_info.
> * @name: name of fence
> * @status: status of fence. 1: signaled 0:active <0:error
> - * @sync_fence_info: array of sync_fence_info for every fence in the
> sync_file
> + * @flags: sync_file_info flags
> + * @num_fences number of fences in the sync_file
> + * @pad: padding for 64-bit alignment, should always be zero
> + * @sync_fence_info: pointer to array of structs sync_fence_info with all
> + * fences in the sync_file
> */
> struct sync_file_info {
> - __u32 len;
> char name[32];
> __s32 status;
> + __u32 flags;
> + __u32 num_fences;
> + __u32 pad;
>
> - __u8 sync_fence_info[0];
> + __u64 sync_fence_info;
> };
>
> #define SYNC_IOC_MAGIC '>'
>
> /**
> + * Opcodes 0, 1 and 2 were burned during a API change to avoid users of the
> + * old API to get weird errors when trying to handling sync_files. The API
> + * change happened during the de-stage of the Sync Framework when there was
> + * no upstream users available.
> + */
> +
> +/**
> * DOC: SYNC_IOC_MERGE - merge two fences
> *
> * Takes a struct sync_merge_data. Creates a new fence containing copies of
> * the sync_pts in both the calling fd and sync_merge_data.fd2. Returns the
> * new fence's fd in sync_merge_data.fence
> */
> -#define SYNC_IOC_MERGE _IOWR(SYNC_IOC_MAGIC, 1, struct
> sync_merge_data)
> +#define SYNC_IOC_MERGE _IOWR(SYNC_IOC_MAGIC, 3, struct
> sync_merge_data)
>
> /**
> * DOC: SYNC_IOC_FENCE_INFO - get detailed information on a fence
> @@ -79,6 +95,6 @@ struct sync_file_info {
> * pt_info is a buffer containing sync_pt_infos for every sync_pt in the
> fence.
> * To iterate over the sync_pt_infos, use the sync_pt_info.len field.
> */
> -#define SYNC_IOC_FENCE_INFO _IOWR(SYNC_IOC_MAGIC, 2, struct sync_file_info)
> +#define SYNC_IOC_FILE_INFO _IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
>
> #endif /* _UAPI_LINUX_SYNC_H */
> --
> 2.5.0
>
