Skip to content

Commit

Permalink
staging: sync: Add internal refcounting to fences
Browse files Browse the repository at this point in the history 
If a fence is released while a timeline that one of it's pts is on is being
signaled, it is possible for that fence to be deleted before it is signaled.
This patch adds a refcount for internal references such as signaled pt
processing.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  • Loading branch information
Erik Gilling authored and Greg Kroah-Hartman committed Mar 4, 2013
1 parent c6f668c commit 0154417
Show file tree
Hide file tree
Showing 2 changed files with 51 additions and 8 deletions.
54 changes: 46 additions & 8 deletions drivers/staging/android/sync.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@

static void sync_fence_signal_pt(struct sync_pt *pt);
static int _sync_pt_has_signaled(struct sync_pt *pt);
static void sync_fence_free(struct kref *kref);

static LIST_HEAD(sync_timeline_list_head);
static DEFINE_SPINLOCK(sync_timeline_list_lock);
Expand Down Expand Up @@ -113,16 +114,19 @@ static void sync_timeline_remove_pt(struct sync_pt *pt)
{
struct sync_timeline *obj = pt->parent;
unsigned long flags;
bool needs_freeing;
bool needs_freeing = false;

spin_lock_irqsave(&obj->active_list_lock, flags);
if (!list_empty(&pt->active_list))
list_del_init(&pt->active_list);
spin_unlock_irqrestore(&obj->active_list_lock, flags);

spin_lock_irqsave(&obj->child_list_lock, flags);
list_del(&pt->child_list);
needs_freeing = obj->destroyed && list_empty(&obj->child_list_head);
if (!list_empty(&pt->child_list)) {
list_del_init(&pt->child_list);
needs_freeing = obj->destroyed &&
list_empty(&obj->child_list_head);
}
spin_unlock_irqrestore(&obj->child_list_lock, flags);

if (needs_freeing)
Expand All @@ -141,18 +145,22 @@ void sync_timeline_signal(struct sync_timeline *obj)
struct sync_pt *pt =
container_of(pos, struct sync_pt, active_list);

if (_sync_pt_has_signaled(pt))
list_move(pos, &signaled_pts);
if (_sync_pt_has_signaled(pt)) {
list_del_init(pos);
list_add(&pt->signaled_list, &signaled_pts);
kref_get(&pt->fence->kref);
}
}

spin_unlock_irqrestore(&obj->active_list_lock, flags);

list_for_each_safe(pos, n, &signaled_pts) {
struct sync_pt *pt =
container_of(pos, struct sync_pt, active_list);
container_of(pos, struct sync_pt, signaled_list);

list_del_init(pos);
sync_fence_signal_pt(pt);
kref_put(&pt->fence->kref, sync_fence_free);
}
}
EXPORT_SYMBOL(sync_timeline_signal);
Expand Down Expand Up @@ -253,6 +261,7 @@ static struct sync_fence *sync_fence_alloc(const char *name)
if (fence->file == NULL)
goto err;

kref_init(&fence->kref);
strlcpy(fence->name, name, sizeof(fence->name));

INIT_LIST_HEAD(&fence->pt_list_head);
Expand Down Expand Up @@ -362,6 +371,16 @@ static int sync_fence_merge_pts(struct sync_fence *dst, struct sync_fence *src)
return 0;
}

static void sync_fence_detach_pts(struct sync_fence *fence)
{
struct list_head *pos, *n;

list_for_each_safe(pos, n, &fence->pt_list_head) {
struct sync_pt *pt = container_of(pos, struct sync_pt, pt_list);
sync_timeline_remove_pt(pt);
}
}

static void sync_fence_free_pts(struct sync_fence *fence)
{
struct list_head *pos, *n;
Expand Down Expand Up @@ -565,18 +584,37 @@ int sync_fence_wait(struct sync_fence *fence, long timeout)
}
EXPORT_SYMBOL(sync_fence_wait);

static void sync_fence_free(struct kref *kref)
{
struct sync_fence *fence = container_of(kref, struct sync_fence, kref);

sync_fence_free_pts(fence);

kfree(fence);
}

static int sync_fence_release(struct inode *inode, struct file *file)
{
struct sync_fence *fence = file->private_data;
unsigned long flags;

/*
* We need to remove all ways to access this fence before droping
* our ref.
*
* start with its membership in the global fence list
*/
spin_lock_irqsave(&sync_fence_list_lock, flags);
list_del(&fence->sync_fence_list);
spin_unlock_irqrestore(&sync_fence_list_lock, flags);

sync_fence_free_pts(fence);
/*
* remove its pts from their parents so that sync_timeline_signal()
* can't reference the fence.
*/
sync_fence_detach_pts(fence);

kfree(fence);
kref_put(&fence->kref, sync_fence_free);

return 0;
}
Expand Down
5 changes: 5 additions & 0 deletions drivers/staging/android/sync.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include <linux/types.h>
#ifdef __KERNEL__

#include <linux/kref.h>
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/spinlock.h>
Expand Down Expand Up @@ -109,6 +110,7 @@ struct sync_timeline {
* @parent: sync_timeline to which this sync_pt belongs
* @child_list: membership in sync_timeline.child_list_head
* @active_list: membership in sync_timeline.active_list_head
* @signaled_list: membership in temorary signaled_list on stack
* @fence: sync_fence to which the sync_pt belongs
* @pt_list: membership in sync_fence.pt_list_head
* @status: 1: signaled, 0:active, <0: error
Expand All @@ -120,6 +122,7 @@ struct sync_pt {
struct list_head child_list;

struct list_head active_list;
struct list_head signaled_list;

struct sync_fence *fence;
struct list_head pt_list;
Expand All @@ -133,6 +136,7 @@ struct sync_pt {
/**
* struct sync_fence - sync fence
* @file: file representing this fence
* @kref: referenace count on fence.
* @name: name of sync_fence. Useful for debugging
* @pt_list_head: list of sync_pts in ths fence. immutable once fence
* is created
Expand All @@ -145,6 +149,7 @@ struct sync_pt {
*/
struct sync_fence {
struct file *file;
struct kref kref;
char name[32];

/* this list is immutable once the fence is created */
Expand Down

0 comments on commit 0154417

Please sign in to comment.