linux-stable/drivers/gpu/drm/drm_global.c
Huang Rui d28d6e6fa5 drm: modify drm_global_item_ref to avoid two times of writing ref->object
In previous drm_global_item_ref, there are two times of writing
ref->object if item->refcount is 0. So this patch does a minor update
to put alloc and init ref firstly, and then to modify the item of glob
array. Use "else" to avoid two times of writing ref->object. It can
make the code logic more clearly.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2016-09-14 15:10:29 -04:00

114 lines
3 KiB
C

/**************************************************************************
*
* Copyright 2008-2009 VMware, Inc., Palo Alto, CA., USA
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
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* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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/*
* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
*/
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <drm/drm_global.h>
struct drm_global_item {
struct mutex mutex;
void *object;
int refcount;
};
static struct drm_global_item glob[DRM_GLOBAL_NUM];
void drm_global_init(void)
{
int i;
for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
struct drm_global_item *item = &glob[i];
mutex_init(&item->mutex);
item->object = NULL;
item->refcount = 0;
}
}
void drm_global_release(void)
{
int i;
for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
struct drm_global_item *item = &glob[i];
BUG_ON(item->object != NULL);
BUG_ON(item->refcount != 0);
}
}
int drm_global_item_ref(struct drm_global_reference *ref)
{
int ret = 0;
struct drm_global_item *item = &glob[ref->global_type];
mutex_lock(&item->mutex);
if (item->refcount == 0) {
ref->object = kzalloc(ref->size, GFP_KERNEL);
if (unlikely(ref->object == NULL)) {
ret = -ENOMEM;
goto error_unlock;
}
ret = ref->init(ref);
if (unlikely(ret != 0))
goto error_free;
item->object = ref->object;
} else {
ref->object = item->object;
}
++item->refcount;
mutex_unlock(&item->mutex);
return 0;
error_free:
kfree(ref->object);
ref->object = NULL;
error_unlock:
mutex_unlock(&item->mutex);
return ret;
}
EXPORT_SYMBOL(drm_global_item_ref);
void drm_global_item_unref(struct drm_global_reference *ref)
{
struct drm_global_item *item = &glob[ref->global_type];
mutex_lock(&item->mutex);
BUG_ON(item->refcount == 0);
BUG_ON(ref->object != item->object);
if (--item->refcount == 0) {
ref->release(ref);
item->object = NULL;
}
mutex_unlock(&item->mutex);
}
EXPORT_SYMBOL(drm_global_item_unref);