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/*
* drivers/dma-buf/sync_file.c
*
* Copyright (C) 2012 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/export.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/anon_inodes.h>
#include <linux/sync_file.h>
#include <uapi/linux/sync_file.h>
static const struct file_operations sync_file_fops;
static struct sync_file *sync_file_alloc(int size)
{
struct sync_file *sync_file;
sync_file = kzalloc(size, GFP_KERNEL);
if (!sync_file)
return NULL;
sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
sync_file, 0);
if (IS_ERR(sync_file->file))
goto err;
kref_init(&sync_file->kref);
init_waitqueue_head(&sync_file->wq);
return sync_file;
err:
kfree(sync_file);
return NULL;
}
static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
{
struct sync_file_cb *check;
struct sync_file *sync_file;
check = container_of(cb, struct sync_file_cb, cb);
sync_file = check->sync_file;
if (atomic_dec_and_test(&sync_file->status))
wake_up_all(&sync_file->wq);
}
/**
* sync_file_create() - creates a sync file
* @fence: fence to add to the sync_fence
*
* Creates a sync_file containg @fence. Once this is called, the sync_file
* takes ownership of @fence. The sync_file can be released with
* fput(sync_file->file). Returns the sync_file or NULL in case of error.
*/
struct sync_file *sync_file_create(struct fence *fence)
{
struct sync_file *sync_file;
sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]));
if (!sync_file)
return NULL;
sync_file->num_fences = 1;
atomic_set(&sync_file->status, 1);
snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%d-%d",
fence->ops->get_driver_name(fence),
fence->ops->get_timeline_name(fence), fence->context,
fence->seqno);
sync_file->cbs[0].fence = fence;
sync_file->cbs[0].sync_file = sync_file;
if (fence_add_callback(fence, &sync_file->cbs[0].cb,
fence_check_cb_func))
atomic_dec(&sync_file->status);
return sync_file;
}
EXPORT_SYMBOL(sync_file_create);
/**
* sync_file_fdget() - get a sync_file from an fd
* @fd: fd referencing a fence
*
* Ensures @fd references a valid sync_file, increments the refcount of the
* backing file. Returns the sync_file or NULL in case of error.
*/
static struct sync_file *sync_file_fdget(int fd)
{
struct file *file = fget(fd);
if (!file)
return NULL;
if (file->f_op != &sync_file_fops)
goto err;
return file->private_data;
err:
fput(file);
return NULL;
}
static void sync_file_add_pt(struct sync_file *sync_file, int *i,
struct fence *fence)
{
sync_file->cbs[*i].fence = fence;
sync_file->cbs[*i].sync_file = sync_file;
if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
fence_check_cb_func)) {
fence_get(fence);
(*i)++;
}
}
/**
* sync_file_merge() - merge two sync_files
* @name: name of new fence
* @a: sync_file a
* @b: sync_file b
*
* Creates a new sync_file which contains copies of all the fences in both
* @a and @b. @a and @b remain valid, independent sync_file. Returns the
* new merged sync_file or NULL in case of error.
*/
static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
struct sync_file *b)
{
int num_fences = a->num_fences + b->num_fences;
struct sync_file *sync_file;
int i, i_a, i_b;
unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
sync_file = sync_file_alloc(size);
if (!sync_file)
return NULL;
atomic_set(&sync_file->status, num_fences);
/*
* Assume sync_file a and b are both ordered and have no
* duplicates with the same context.
*
* If a sync_file can only be created with sync_file_merge
* and sync_file_create, this is a reasonable assumption.
*/
for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
struct fence *pt_a = a->cbs[i_a].fence;
struct fence *pt_b = b->cbs[i_b].fence;
if (pt_a->context < pt_b->context) {
sync_file_add_pt(sync_file, &i, pt_a);
i_a++;
} else if (pt_a->context > pt_b->context) {
sync_file_add_pt(sync_file, &i, pt_b);
i_b++;
} else {
if (pt_a->seqno - pt_b->seqno <= INT_MAX)
sync_file_add_pt(sync_file, &i, pt_a);
else
sync_file_add_pt(sync_file, &i, pt_b);
i_a++;
i_b++;
}
}
for (; i_a < a->num_fences; i_a++)
sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
for (; i_b < b->num_fences; i_b++)
sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
if (num_fences > i)
atomic_sub(num_fences - i, &sync_file->status);
sync_file->num_fences = i;
strlcpy(sync_file->name, name, sizeof(sync_file->name));
return sync_file;
}
static void sync_file_free(struct kref *kref)
{
struct sync_file *sync_file = container_of(kref, struct sync_file,
kref);
int i;
for (i = 0; i < sync_file->num_fences; ++i) {
fence_remove_callback(sync_file->cbs[i].fence,
&sync_file->cbs[i].cb);
fence_put(sync_file->cbs[i].fence);
}
kfree(sync_file);
}
static int sync_file_release(struct inode *inode, struct file *file)
{
struct sync_file *sync_file = file->private_data;
kref_put(&sync_file->kref, sync_file_free);
return 0;
}
static unsigned int sync_file_poll(struct file *file, poll_table *wait)
{
struct sync_file *sync_file = file->private_data;
int status;
poll_wait(file, &sync_file->wq, wait);
status = atomic_read(&sync_file->status);
if (!status)
return POLLIN;
if (status < 0)
return POLLERR;
return 0;
}
static long sync_file_ioctl_merge(struct sync_file *sync_file,
unsigned long arg)
{
int fd = get_unused_fd_flags(O_CLOEXEC);
int err;
struct sync_file *fence2, *fence3;
struct sync_merge_data data;
if (fd < 0)
return fd;
if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
err = -EFAULT;
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;
goto err_put_fd;
}
data.name[sizeof(data.name) - 1] = '\0';
fence3 = sync_file_merge(data.name, sync_file, fence2);
if (!
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