1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2020 Intel
  4 *
  5 * Based on drivers/base/devres.c
  6 */
  7
  8#include <drm/drm_managed.h>
  9
 10#include <linux/list.h>
 11#include <linux/slab.h>
 12#include <linux/spinlock.h>
 13
 14#include <drm/drm_device.h>
 15#include <drm/drm_print.h>
 16
 17#include "drm_internal.h"
 18
 19/**
 20 * DOC: managed resources
 21 *
 22 * Inspired by struct &device managed resources, but tied to the lifetime of
 23 * struct &drm_device, which can outlive the underlying physical device, usually
 24 * when userspace has some open files and other handles to resources still open.
 25 *
 26 * Release actions can be added with drmm_add_action(), memory allocations can
 27 * be done directly with drmm_kmalloc() and the related functions. Everything
 28 * will be released on the final drm_dev_put() in reverse order of how the
 29 * release actions have been added and memory has been allocated since driver
 30 * loading started with devm_drm_dev_alloc().
 31 *
 32 * Note that release actions and managed memory can also be added and removed
 33 * during the lifetime of the driver, all the functions are fully concurrent
 34 * safe. But it is recommended to use managed resources only for resources that
 35 * change rarely, if ever, during the lifetime of the &drm_device instance.
 36 */
 37
 38struct drmres_node {
 39	struct list_head	entry;
 40	drmres_release_t	release;
 41	const char		*name;
 42	size_t			size;
 43};
 44
 45struct drmres {
 46	struct drmres_node		node;
 47	/*
 48	 * Some archs want to perform DMA into kmalloc caches
 49	 * and need a guaranteed alignment larger than
 50	 * the alignment of a 64-bit integer.
 51	 * Thus we use ARCH_KMALLOC_MINALIGN here and get exactly the same
 52	 * buffer alignment as if it was allocated by plain kmalloc().
 53	 */
 54	u8 __aligned(ARCH_KMALLOC_MINALIGN) data[];
 55};
 56
 57static void free_dr(struct drmres *dr)
 58{
 59	kfree_const(dr->node.name);
 60	kfree(dr);
 61}
 62
 63void drm_managed_release(struct drm_device *dev)
 64{
 65	struct drmres *dr, *tmp;
 66
 67	drm_dbg_drmres(dev, "drmres release begin\n");
 68	list_for_each_entry_safe(dr, tmp, &dev->managed.resources, node.entry) {
 69		drm_dbg_drmres(dev, "REL %p %s (%zu bytes)\n",
 70			       dr, dr->node.name, dr->node.size);
 71
 72		if (dr->node.release)
 73			dr->node.release(dev, dr->node.size ? *(void **)&dr->data : NULL);
 74
 75		list_del(&dr->node.entry);
 76		free_dr(dr);
 77	}
 78	drm_dbg_drmres(dev, "drmres release end\n");
 79}
 80
 81/*
 82 * Always inline so that kmalloc_track_caller tracks the actual interesting
 83 * caller outside of drm_managed.c.
 84 */
 85static __always_inline struct drmres * alloc_dr(drmres_release_t release,
 86						size_t size, gfp_t gfp, int nid)
 87{
 88	size_t tot_size;
 89	struct drmres *dr;
 90
 91	/* We must catch any near-SIZE_MAX cases that could overflow. */
 92	if (unlikely(check_add_overflow(sizeof(*dr), size, &tot_size)))
 93		return NULL;
 94
 95	dr = kmalloc_node_track_caller(tot_size, gfp, nid);
 96	if (unlikely(!dr))
 97		return NULL;
 98
 99	memset(dr, 0, offsetof(struct drmres, data));
100
101	INIT_LIST_HEAD(&dr->node.entry);
102	dr->node.release = release;
103	dr->node.size = size;
104
105	return dr;
106}
107
108static void del_dr(struct drm_device *dev, struct drmres *dr)
109{
110	list_del_init(&dr->node.entry);
111
112	drm_dbg_drmres(dev, "DEL %p %s (%lu bytes)\n",
113		       dr, dr->node.name, (unsigned long) dr->node.size);
114}
115
116static void add_dr(struct drm_device *dev, struct drmres *dr)
117{
118	unsigned long flags;
119
120	spin_lock_irqsave(&dev->managed.lock, flags);
121	list_add(&dr->node.entry, &dev->managed.resources);
122	spin_unlock_irqrestore(&dev->managed.lock, flags);
123
124	drm_dbg_drmres(dev, "ADD %p %s (%lu bytes)\n",
125		       dr, dr->node.name, (unsigned long) dr->node.size);
126}
127
128void drmm_add_final_kfree(struct drm_device *dev, void *container)
129{
130	WARN_ON(dev->managed.final_kfree);
131	WARN_ON(dev < (struct drm_device *) container);
132	WARN_ON(dev + 1 > (struct drm_device *) (container + ksize(container)));
133	dev->managed.final_kfree = container;
134}
135
136int __drmm_add_action(struct drm_device *dev,
137		      drmres_release_t action,
138		      void *data, const char *name)
139{
140	struct drmres *dr;
141	void **void_ptr;
142
143	dr = alloc_dr(action, data ? sizeof(void*) : 0,
144		      GFP_KERNEL | __GFP_ZERO,
145		      dev_to_node(dev->dev));
146	if (!dr) {
147		drm_dbg_drmres(dev, "failed to add action %s for %p\n",
148			       name, data);
149		return -ENOMEM;
150	}
151
152	dr->node.name = kstrdup_const(name, GFP_KERNEL);
153	if (data) {
154		void_ptr = (void **)&dr->data;
155		*void_ptr = data;
156	}
157
158	add_dr(dev, dr);
159
160	return 0;
161}
162EXPORT_SYMBOL(__drmm_add_action);
163
164int __drmm_add_action_or_reset(struct drm_device *dev,
165			       drmres_release_t action,
166			       void *data, const char *name)
167{
168	int ret;
169
170	ret = __drmm_add_action(dev, action, data, name);
171	if (ret)
172		action(dev, data);
173
174	return ret;
175}
176EXPORT_SYMBOL(__drmm_add_action_or_reset);
177
178/**
179 * drmm_kmalloc - &drm_device managed kmalloc()
180 * @dev: DRM device
181 * @size: size of the memory allocation
182 * @gfp: GFP allocation flags
183 *
184 * This is a &drm_device managed version of kmalloc(). The allocated memory is
185 * automatically freed on the final drm_dev_put(). Memory can also be freed
186 * before the final drm_dev_put() by calling drmm_kfree().
187 */
188void *drmm_kmalloc(struct drm_device *dev, size_t size, gfp_t gfp)
189{
190	struct drmres *dr;
191
192	dr = alloc_dr(NULL, size, gfp, dev_to_node(dev->dev));
193	if (!dr) {
194		drm_dbg_drmres(dev, "failed to allocate %zu bytes, %u flags\n",
195			       size, gfp);
196		return NULL;
197	}
198	dr->node.name = kstrdup_const("kmalloc", GFP_KERNEL);
199
200	add_dr(dev, dr);
201
202	return dr->data;
203}
204EXPORT_SYMBOL(drmm_kmalloc);
205
206/**
207 * drmm_kstrdup - &drm_device managed kstrdup()
208 * @dev: DRM device
209 * @s: 0-terminated string to be duplicated
210 * @gfp: GFP allocation flags
211 *
212 * This is a &drm_device managed version of kstrdup(). The allocated memory is
213 * automatically freed on the final drm_dev_put() and works exactly like a
214 * memory allocation obtained by drmm_kmalloc().
215 */
216char *drmm_kstrdup(struct drm_device *dev, const char *s, gfp_t gfp)
217{
218	size_t size;
219	char *buf;
220
221	if (!s)
222		return NULL;
223
224	size = strlen(s) + 1;
225	buf = drmm_kmalloc(dev, size, gfp);
226	if (buf)
227		memcpy(buf, s, size);
228	return buf;
229}
230EXPORT_SYMBOL_GPL(drmm_kstrdup);
231
232/**
233 * drmm_kfree - &drm_device managed kfree()
234 * @dev: DRM device
235 * @data: memory allocation to be freed
236 *
237 * This is a &drm_device managed version of kfree() which can be used to
238 * release memory allocated through drmm_kmalloc() or any of its related
239 * functions before the final drm_dev_put() of @dev.
240 */
241void drmm_kfree(struct drm_device *dev, void *data)
242{
243	struct drmres *dr_match = NULL, *dr;
244	unsigned long flags;
245
246	if (!data)
247		return;
248
249	spin_lock_irqsave(&dev->managed.lock, flags);
250	list_for_each_entry(dr, &dev->managed.resources, node.entry) {
251		if (dr->data == data) {
252			dr_match = dr;
253			del_dr(dev, dr_match);
254			break;
255		}
256	}
257	spin_unlock_irqrestore(&dev->managed.lock, flags);
258
259	if (WARN_ON(!dr_match))
260		return;
261
262	free_dr(dr_match);
263}
264EXPORT_SYMBOL(drmm_kfree);