[PATCH v6 5/6] staging/android: refactor SYNC_IOC_FILE_INFO
From: Gustavo Padovan
Date: Wed Mar 02 2016 - 14:52:40 EST
From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Change SYNC_IOC_FILE_INFO behaviour to avoid future API breaks and
optimize buffer
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.
Also, info->sync_fence_info was converted to __u64 pointer to prevent
32bit compatibility issues.
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);
}
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
Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
---
drivers/staging/android/sync.c | 64 ++++++++++++++++++++-----------------
drivers/staging/android/uapi/sync.h | 9 ++----
2 files changed, 38 insertions(+), 35 deletions(-)
diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index dc5f382..3604e453 100644
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -479,13 +479,9 @@ 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),
@@ -495,28 +491,20 @@ 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 in, *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(&in, (void __user *)arg, sizeof(in)))
return -EFAULT;
- if (size < sizeof(struct sync_file_info))
- return -EINVAL;
-
- if (size > 4096)
- size = 4096;
-
- info = kzalloc(size, GFP_KERNEL);
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;
@@ -525,29 +513,47 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
if (info->status >= 0)
info->status = !info->status;
- info->num_fences = sync_file->num_fences;
-
- 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 (!in.num_fences)
+ goto no_fences;
- for (i = 0; i < sync_file->num_fences; ++i) {
- struct fence *fence = sync_file->cbs[i].fence;
+ if (in.num_fences < sync_file->num_fences) {
+ ret = -EINVAL;
+ goto out;
+ }
- 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) {
+ ret = -ENOMEM;
+ goto out;
+ }
- 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((void __user *)in.sync_fence_info, fence_info, size)) {
+ ret = -EFAULT;
+ goto out;
}
- info->len = len;
+ info->sync_fence_info = in.sync_fence_info;
+
+no_fences:
+ 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(fence_info);
kfree(info);
return ret;
diff --git a/drivers/staging/android/uapi/sync.h b/drivers/staging/android/uapi/sync.h
index a6c648c..f064923 100644
--- a/drivers/staging/android/uapi/sync.h
+++ b/drivers/staging/android/uapi/sync.h
@@ -42,21 +42,18 @@ struct sync_fence_info {
/**
* 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
* @num_fences number of fences in the sync_file
- * @sync_fence_info: array of sync_fence_info for every fence in the sync_file
+ * @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 num_fences;
- __u8 sync_fence_info[0];
+ __u64 sync_fence_info;
};
#define SYNC_IOC_MAGIC '>'
--
2.5.0