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dma-buf/sync_file: refactor fence storage in struct sync_file
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Create sync_file->fence to abstract the type of fence we are using for
each sync_file. If only one fence is present we use a normal struct fence
but if there is more fences to be added to the sync_file a fence_array
is created.

This change cleans up sync_file a bit. We don't need to have sync_file_cb
array anymore. Instead, as we always have  one fence, only one fence
callback is registered per sync_file.

v2: Comments from Chris Wilson and Christian König
	- Not using fence_ops anymore
	- fence_is_array() was created to differentiate fence from fence_array
	- fence_array_teardown() is now exported and used under fence_is_array()
	- struct sync_file lost num_fences member

v3: Comments from Chris Wilson and Christian König
	- struct sync_file lost status member in favor of fence_is_signaled()
	- drop use of fence_array_teardown()
	- use sizeof(*fence) to allocate only an array on fence pointers

v4: Comments from Chris Wilson
	- use sizeof(*fence) to reallocate array
	- fix typo in comments
	- protect num_fences sum against overflows
	- use array->base instead of casting the to struct fence

v5: fixes checkpatch warnings

v6: fix case where all fences are signaled.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
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Gustavo Padovan authored and Sumit Semwal committed Aug 11, 2016
1 parent e1aaf31 commit a02b9dc
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Showing 3 changed files with 129 additions and 74 deletions.
174 changes: 115 additions & 59 deletions drivers/dma-buf/sync_file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,11 +28,11 @@

static const struct file_operations sync_file_fops;

static struct sync_file *sync_file_alloc(int size)
static struct sync_file *sync_file_alloc(void)
{
struct sync_file *sync_file;

sync_file = kzalloc(size, GFP_KERNEL);
sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
if (!sync_file)
return NULL;

Expand All @@ -45,6 +45,8 @@ static struct sync_file *sync_file_alloc(int size)

init_waitqueue_head(&sync_file->wq);

INIT_LIST_HEAD(&sync_file->cb.node);

return sync_file;

err:
Expand All @@ -54,14 +56,11 @@ static struct sync_file *sync_file_alloc(int size)

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;
sync_file = container_of(cb, struct sync_file, cb);

if (atomic_dec_and_test(&sync_file->status))
wake_up_all(&sync_file->wq);
wake_up_all(&sync_file->wq);
}

/**
Expand All @@ -76,22 +75,18 @@ 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]));
sync_file = sync_file_alloc();
if (!sync_file)
return NULL;

sync_file->num_fences = 1;
atomic_set(&sync_file->status, 1);
sync_file->fence = fence;

snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%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);
fence_add_callback(fence, &sync_file->cb, fence_check_cb_func);

return sync_file;
}
Expand Down Expand Up @@ -121,14 +116,49 @@ static struct sync_file *sync_file_fdget(int fd)
return NULL;
}

static void sync_file_add_pt(struct sync_file *sync_file, int *i,
struct fence *fence)
static int sync_file_set_fence(struct sync_file *sync_file,
struct fence **fences, int num_fences)
{
sync_file->cbs[*i].fence = fence;
sync_file->cbs[*i].sync_file = sync_file;
struct fence_array *array;

/*
* The reference for the fences in the new sync_file and held
* in add_fence() during the merge procedure, so for num_fences == 1
* we already own a new reference to the fence. For num_fence > 1
* we own the reference of the fence_array creation.
*/
if (num_fences == 1) {
sync_file->fence = fences[0];
} else {
array = fence_array_create(num_fences, fences,
fence_context_alloc(1), 1, false);
if (!array)
return -ENOMEM;

sync_file->fence = &array->base;
}

if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
fence_check_cb_func)) {
return 0;
}

static struct fence **get_fences(struct sync_file *sync_file, int *num_fences)
{
if (fence_is_array(sync_file->fence)) {
struct fence_array *array = to_fence_array(sync_file->fence);

*num_fences = array->num_fences;
return array->fences;
}

*num_fences = 1;
return &sync_file->fence;
}

static void add_fence(struct fence **fences, int *i, struct fence *fence)
{
fences[*i] = fence;

if (!fence_is_signaled(fence)) {
fence_get(fence);
(*i)++;
}
Expand All @@ -147,16 +177,24 @@ static void sync_file_add_pt(struct sync_file *sync_file, int *i,
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]);
struct fence **fences, **nfences, **a_fences, **b_fences;
int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;

sync_file = sync_file_alloc(size);
sync_file = sync_file_alloc();
if (!sync_file)
return NULL;

atomic_set(&sync_file->status, num_fences);
a_fences = get_fences(a, &a_num_fences);
b_fences = get_fences(b, &b_num_fences);
if (a_num_fences > INT_MAX - b_num_fences)
return NULL;

num_fences = a_num_fences + b_num_fences;

fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
if (!fences)
goto err;

/*
* Assume sync_file a and b are both ordered and have no
Expand All @@ -165,55 +203,73 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
* 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;
for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
struct fence *pt_a = a_fences[i_a];
struct fence *pt_b = b_fences[i_b];

if (pt_a->context < pt_b->context) {
sync_file_add_pt(sync_file, &i, pt_a);
add_fence(fences, &i, pt_a);

i_a++;
} else if (pt_a->context > pt_b->context) {
sync_file_add_pt(sync_file, &i, pt_b);
add_fence(fences, &i, pt_b);

i_b++;
} else {
if (pt_a->seqno - pt_b->seqno <= INT_MAX)
sync_file_add_pt(sync_file, &i, pt_a);
add_fence(fences, &i, pt_a);
else
sync_file_add_pt(sync_file, &i, pt_b);
add_fence(fences, &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_a < a_num_fences; i_a++)
add_fence(fences, &i, a_fences[i_a]);

for (; i_b < b_num_fences; i_b++)
add_fence(fences, &i, b_fences[i_b]);

if (i == 0) {
add_fence(fences, &i, a_fences[0]);
i++;
}

for (; i_b < b->num_fences; i_b++)
sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
if (num_fences > i) {
nfences = krealloc(fences, i * sizeof(*fences),
GFP_KERNEL);
if (!nfences)
goto err;

fences = nfences;
}

if (sync_file_set_fence(sync_file, fences, i) < 0) {
kfree(fences);
goto err;
}

if (num_fences > i)
atomic_sub(num_fences - i, &sync_file->status);
sync_file->num_fences = i;
fence_add_callback(sync_file->fence, &sync_file->cb,
fence_check_cb_func);

strlcpy(sync_file->name, name, sizeof(sync_file->name));
return sync_file;

err:
fput(sync_file->file);
return NULL;

}

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);
}

fence_remove_callback(sync_file->fence, &sync_file->cb);
fence_put(sync_file->fence);
kfree(sync_file);
}

Expand All @@ -232,9 +288,9 @@ static unsigned int sync_file_poll(struct file *file, poll_table *wait)

poll_wait(file, &sync_file->wq, wait);

status = atomic_read(&sync_file->status);
status = fence_is_signaled(sync_file->fence);

if (!status)
if (status)
return POLLIN;
if (status < 0)
return POLLERR;
Expand Down Expand Up @@ -315,15 +371,18 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
{
struct sync_file_info info;
struct sync_fence_info *fence_info = NULL;
struct fence **fences;
__u32 size;
int ret, i;
int num_fences, ret, i;

if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
return -EFAULT;

if (info.flags || info.pad)
return -EINVAL;

fences = get_fences(sync_file, &num_fences);

/*
* Passing num_fences = 0 means that userspace doesn't want to
* retrieve any sync_fence_info. If num_fences = 0 we skip filling
Expand All @@ -333,16 +392,16 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
if (!info.num_fences)
goto no_fences;

if (info.num_fences < sync_file->num_fences)
if (info.num_fences < num_fences)
return -EINVAL;

size = sync_file->num_fences * sizeof(*fence_info);
size = num_fences * sizeof(*fence_info);
fence_info = kzalloc(size, GFP_KERNEL);
if (!fence_info)
return -ENOMEM;

for (i = 0; i < sync_file->num_fences; ++i)
sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
for (i = 0; i < num_fences; i++)
sync_fill_fence_info(fences[i], &fence_info[i]);

if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
size)) {
Expand All @@ -352,11 +411,8 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,

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;
info.status = fence_is_signaled(sync_file->fence);
info.num_fences = num_fences;

if (copy_to_user((void __user *)arg, &info, sizeof(info)))
ret = -EFAULT;
Expand Down
12 changes: 9 additions & 3 deletions drivers/staging/android/sync_debug.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -135,10 +135,16 @@ static void sync_print_sync_file(struct seq_file *s,
int i;

seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
sync_status_str(atomic_read(&sync_file->status)));
sync_status_str(!fence_is_signaled(sync_file->fence)));

for (i = 0; i < sync_file->num_fences; ++i)
sync_print_fence(s, sync_file->cbs[i].fence, true);
if (fence_is_array(sync_file->fence)) {
struct fence_array *array = to_fence_array(sync_file->fence);

for (i = 0; i < array->num_fences; ++i)
sync_print_fence(s, array->fences[i], true);
} else {
sync_print_fence(s, sync_file->fence, true);
}
}

static int sync_debugfs_show(struct seq_file *s, void *unused)
Expand Down
17 changes: 5 additions & 12 deletions include/linux/sync_file.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,23 +19,17 @@
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/fence.h>

struct sync_file_cb {
struct fence_cb cb;
struct fence *fence;
struct sync_file *sync_file;
};
#include <linux/fence-array.h>

/**
* struct sync_file - sync file to export to the userspace
* @file: file representing this fence
* @kref: reference count on fence.
* @name: name of sync_file. Useful for debugging
* @sync_file_list: membership in global file list
* @num_fences: number of sync_pts in the fence
* @wq: wait queue for fence signaling
* @status: 0: signaled, >0:active, <0: error
* @cbs: sync_pts callback information
* @fence: fence with the fences in the sync_file
* @cb: fence callback information
*/
struct sync_file {
struct file *file;
Expand All @@ -44,12 +38,11 @@ struct sync_file {
#ifdef CONFIG_DEBUG_FS
struct list_head sync_file_list;
#endif
int num_fences;

wait_queue_head_t wq;
atomic_t status;

struct sync_file_cb cbs[];
struct fence *fence;
struct fence_cb cb;
};

struct sync_file *sync_file_create(struct fence *fence);
Expand Down

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