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// SPDX-License-Identifier: MIT
/*
* Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
*
* Based on bo.c which bears the following copyright notice,
* but is dual licensed:
*
* Copyright (c) 2006-2009 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,
* distribute, sub license, and/or sell copies of the Software, and to
* 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,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
*/
#include <linux/dma-resv.h>
#include <linux/dma-fence-array.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/mmu_notifier.h>
#include <linux/seq_file.h>
/**
* DOC: Reservation Object Overview
*
* The reservation object provides a mechanism to manage a container of
* dma_fence object associated with a resource. A reservation object
* can have any number of fences attaches to it. Each fence carries an usage
* parameter determining how the operation represented by the fence is using the
* resource. The RCU mechanism is used to protect read access to fences from
* locked write-side updates.
*
* See struct dma_resv for more details.
*/
DEFINE_WD_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
/* Mask for the lower fence pointer bits */
#define DMA_RESV_LIST_MASK 0x3
struct dma_resv_list {
struct rcu_head rcu;
u32 num_fences, max_fences;
struct dma_fence __rcu *table[];
};
/* Extract the fence and usage flags from an RCU protected entry in the list. */
static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
struct dma_resv *resv, struct dma_fence **fence,
enum dma_resv_usage *usage)
{
long tmp;
tmp = (long)rcu_dereference_check(list->table[index],
resv ? dma_resv_held(resv) : true);
*fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
if (usage)
*usage = tmp & DMA_RESV_LIST_MASK;
}
/* Set the fence and usage flags at the specific index in the list. */
static void dma_resv_list_set(struct dma_resv_list *list,
unsigned int index,
struct dma_fence *fence,
enum dma_resv_usage usage)
{
long tmp = ((long)fence) | usage;
RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
}
/*
* Allocate a new dma_resv_list and make sure to correctly initialize
* max_fences.
*/
static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
{
struct dma_resv_list *list;
size_t size;
/* Round up to the next kmalloc bucket size. */
size = kmalloc_size_roundup(struct_size(list, table, max_fences));
list = kmalloc(size, GFP_KERNEL);
if (!list)
return NULL;
/* Given the resulting bucket size, recalculated max_fences. */
list->max_fences = (size - offsetof(typeof(*list), table)) /
sizeof(*list->table);
return list;
}
/* Free a dma_resv_list and make sure to drop all references. */
static void dma_resv_list_free(struct dma_resv_list *list)
{
unsigned int i;
if (!list)
return;
for (i = 0; i < list->num_fences; ++i) {
struct dma_fence *fence;
dma_resv_list_entry(list, i, NULL, &fence, NULL);
dma_fence_put(fence);
}
kfree_rcu(list, rcu);
}
/**
* dma_resv_init - initialize a reservation object
* @obj: the reservation object
*/
void dma_resv_init(struct dma_resv *obj)
{
ww_mutex_init(&obj->lock, &reservation_ww_class);
RCU_INIT_POINTER(obj->fences, NULL);
}
EXPORT_SYMBOL(dma_resv_init);
/**
* dma_resv_fini - destroys a reservation object
* @obj: the reservation object
*/
void dma_resv_fini(struct dma_resv *obj)
{
/*
* This object should be dead and all references must have
* been released to it, so no need to be protected with rcu.
*/
dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
ww_mutex_destroy(&obj->lock);
}
EXPORT_SYMBOL(dma_resv_fini);
/* Dereference the fences while ensuring RCU rules */
static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
{
return rcu_dereference_check(obj->fences, dma_resv_held(obj));
}
/**
* dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
* @obj: reservation object
* @num_fences: number of fences we want to add
*
* Should be called before dma_resv_add_fence(). Must be called with @obj
* locked through dma_resv_lock().
*
* Note that the preallocated slots need to be re-reserved if @obj is unlocked
* at any time before calling dma_resv_add_fence(). This is validated when
* CONFIG_DEBUG_MUTEXES is enabled.
*
* RETURNS
* Zero for success, or -errno
*/
int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
{
struct dma_resv_list *old, *new;
unsigned int i, j, k, max;
dma_resv_assert_held(obj);
old = dma_resv_fences_list(obj);
if (old && old->max_fences) {
if ((old->num_fences + num_fences) <= old->max_fences)
return 0;
max = max(old->num_fences + num_fences, old->max_fences * 2);
} else {
max = max(4ul, roundup_pow_of_two(num_fences));
}
new = dma_resv_list_alloc(max);
if (!new)
return -ENOMEM;
/*
* no need to bump fence refcounts, rcu_read access
* requires the use of kref_get_unless_zero, and the
* references from the old struct are carried over to
* the new.
*/
for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
enum dma_resv_usage usage;
struct dma_fence *fence;
dma_resv_list_entry(old, i, obj, &fence, &usage);
if (dma_fence_is_signaled(fence))
RCU_INIT_POINTER(new->table[--k], fence);
else
dma_resv_list_set(new, j++, fence, usage);
}
new->num_fences = j;
/*
* We are not changing the effective set of fences here so can
* merely update the pointer to the new array; both existing
* readers and new readers will see exactly the same set of
* active (unsignaled) fences. Individual fences and the
* old array are protected by RCU and so will not vanish under
* the gaze of the rcu_read_lock() readers.
*/
rcu_assign_pointer(obj->fences, new);
if (!old)
return 0;
/* Drop the references to the signaled fences */
for (i = k; i < max; ++i) {
struct dma_fence *fence;
fence = rcu_dereference_protected(new->table[i],
dma_resv_held(obj));
dma_fence_put(fence);
}
kfree_rcu(old, rcu);
return 0;
}
EXPORT_SYMBOL(dma_resv_reserve_fences);
#ifdef CONFIG_DEBUG_MUTEXES
/**
* dma_resv_reset_max_fences - reset fences for debugging
* @obj: the dma_resv object to reset
*
* Reset the number of pre-reserved fence slots to test that drivers do
* correct slot allocation using dma_resv_reserve_fences(). See also
* &dma_resv_list.max_fences.
*/
void dma_resv_reset_max_fences(struct dma_resv *obj)
{
struct dma_resv_list *fences = dma_resv_fences_list(obj);
dma_resv_assert_held(obj);
/* Test fence slot reservation */
if (fences)
fences->max_fences = fences->num_fences;
}
EXPORT_SYMBOL(dma_resv_reset_max_fences);
#endif
/**
* dma_resv_add_fence - Add a fence to the dma_resv obj
* @obj: the reservation object
* @fence: the fence to add
* @usage: how the fence is used, see enum dma_resv_usage
*
* Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
* dma_resv_reserve_fences() has been called.
*
* See also &dma_resv.fence for a discussion of the semantics.
*/
void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
enum dma_resv_usage usage)
{
struct dma_resv_list *fobj;
struct dma_fence *old;
unsigned int i, count;
dma_fence_get(fence);
dma_resv_assert_held(obj);
/* Drivers should not add containers here, instead add each fence
* individually.
*/
WARN_ON(dma_fence_is_container(fence));
fobj = dma_resv_fences_list(obj);
count = fobj->num_fences;
for (i = 0; i < count; ++i) {
enum dma_resv_usage old_usage;
dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
if ((old->context == fence->context && old_usage >= usage &&
dma_fence_is_later_or_same(fence, old)) ||
dma_fence_is_signaled(old)) {
dma_resv_list_set(fobj, i, fence, usage);
dma_fence_put(old);
return;
}
}
BUG_ON(fobj->num_fences >= fobj->max_fences);
count++;
dma_resv_list_set(fobj, i, fence, usage);
/* pointer update must be visible before we extend the num_fences */
smp_store_mb(fobj->num_fences, count);
}
EXPORT_SYMBOL(dma_resv_add_fence);
/**
* dma_resv_replace_fences - replace fences in the dma_resv obj
* @obj: the reservation object
* @context: the context of the fences to replace
* @replacement: the new fence to use instead
* @usage: how the new fence is used, see enum dma_resv_usage
*
* Replace fences with a specified context with a new fence. Only valid if the
* operation represented by the original fence has no longer access to the
* resources represented by the dma_resv object when the new fence completes.
*
* And example for using this is replacing a preemption fence with a page table
* update fence which makes the resource inaccessible.
*/
void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
struct dma_fence *replacement,
enum dma_resv_usage usage)
{
struct dma_resv_list *list;
unsigned int i;
dma_resv_assert_held(obj);
list = dma_resv_fences_list(obj);
for (i = 0; list && i < list->num_fences; ++i) {
struct dma_fence *old;
dma_resv_list_entry(list, i, obj, &old, NULL);
if (old->context != context)
continue;
dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
dma_fence_put(old);
}
}
EXPORT_SYMBOL(dma_resv_replace_fences);
/* Restart the unlocked iteration by initializing the cursor object. */
static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
{
cursor->index = 0;
cursor->num_fences = 0;
cursor->fences = dma_resv_fences_list(cursor->obj);
if (cursor->fences)
cursor->num_fences = cursor->fences->num_fences;
cursor->is_restarted = true;
}
/* Walk to the next not signaled fence and grab a reference to it */
static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
{
if (!cursor->fences)
return;
do {
/* Drop the reference from the previous round */
dma_fence_put(cursor->fence);
if (cursor->index >= cursor->num_fences) {
cursor->fence = NULL;
break;
}
dma_resv_list_entry(cursor->fences, cursor->index++,
cursor->obj, &cursor->fence,
&cursor->fence_usage);
cursor->fence = dma_fence_get_rcu(cursor->fence);
if (!cursor->fence) {
dma_resv_iter_restart_unlocked(cursor);
continue;
}
if (!dma_fence_is_signaled(cursor->fence) &&
cursor->usage >= cursor->fence_usage)
break;
} while (true);
}
/**
* dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
* @cursor: the cursor with the current position
*
* Subsequent fences are iterated with dma_resv_iter_next_unlocked().
*
* Beware that the iterator can be restarted. Code which accumulates statistics
* or similar needs to check for this with dma_resv_iter_is_restarted(). For
* this reason prefer the locked dma_resv_iter_first() whenever possible.
*
* Returns the first fence from an unlocked dma_resv obj.
*/
struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
{
rcu_read_lock();
do {
dma_resv_iter_restart_unlocked(cursor);
dma_resv_iter_walk_unlocked(cursor);
} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
rcu_read_unlock();
return cursor->fence;
}
EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
/**
* dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
* @cursor: the cursor with the current position
*
* Beware that the iterator can be restarted. Code which accumulates statistics
* or similar needs to check for this with dma_resv_iter_is_restarted(). For
* this reason prefer the locked dma_resv_iter_next() whenever possible.
*
* Returns the next fence from an unlocked dma_resv obj.
*/
struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
{
bool restart;
rcu_read_lock();
cursor->is_restarted = false;
restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
do {
if (restart)
dma_resv_iter_restart_unlocked(cursor);
dma_resv_iter_walk_unlocked(cursor);
restart = true;
} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
rcu_read_unlock();
return cursor->fence;
}
EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
/**
* dma_resv_iter_first - first fence from a locked dma_resv object
* @cursor: cursor to record the current position
*
* Subsequent fences are iterated with dma_resv_iter_next_unlocked().
*
* Return the first fence in the dma_resv object while holding the
* &dma_resv.lock.
*/
struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
{
struct dma_fence *fence;
dma_resv_assert_held(cursor->obj);
cursor->index = 0;
cursor->fences = dma_resv_fences_list(cursor->obj);
fence = dma_resv_iter_next(cursor);
cursor->is_restarted = true;
return fence;
}
EXPORT_SYMBOL_GPL(dma_resv_iter_first);
/**
* dma_resv_iter_next - next fence from a locked dma_resv object
* @cursor: cursor to record the current position
*
* Return the next fences from the dma_resv object while holding the
* &dma_resv.lock.
*/
struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
{
struct dma_fence *fence;
dma_resv_assert_held(cursor->obj);
cursor->is_restarted = false;
do {
if (!cursor->fences ||
cursor->index >= cursor->fences->num_fences)
return NULL;
dma_resv_list_entry(cursor->fences, cursor->index++,
cursor->obj, &fence, &cursor->fence_usage);
} while (cursor->fence_usage > cursor->usage);
return fence;
}
EXPORT_SYMBOL_GPL(dma_resv_iter_next);
/**
* dma_resv_copy_fences - Copy all fences from src to dst.
* @dst: the destination reservation object
* @src: the source reservation object
*
* Copy all fences from src to dst. dst-lock must be held.
*/
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
{
struct dma_resv_iter cursor;
struct dma_resv_list *list;
struct dma_fence *f;
dma_resv_assert_held(dst);
list = NULL;
dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
dma_resv_for_each_fence_unlocked(&cursor, f) {
if (dma_resv_iter_is_restarted(&cursor)) {
dma_resv_list_free(list);
list = dma_resv_list_alloc(cursor.num_fences);
if (!list) {
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
list->num_fences = 0;
}
dma_fence_get(f);
dma_resv_list_set(list, list->num_fences++, f,
dma_resv_iter_usage(&cursor));
}
dma_resv_iter_end(&cursor);
list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
dma_resv_list_free(list);
return 0;
}
EXPORT_SYMBOL(dma_resv_copy_fences);
/**
* dma_resv_get_fences - Get an object's fences
* fences without update side lock held
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
* @num_fences: the number of fences returned
* @fences: the array of fence ptrs returned (array is krealloc'd to the
* required size, and must be freed by caller)
*
* Retrieve all fences from the reservation object.
* Returns either zero or -ENOMEM.
*/
int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
unsigned int *num_fences, struct dma_fence ***fences)
{
struct dma_resv_iter cursor;
struct dma_fence *fence;
*num_fences = 0;
*fences = NULL;
dma_resv_iter_begin(&cursor, obj, usage);
dma_resv_for_each_fence_unlocked(&cursor, fence) {
if (dma_resv_iter_is_restarted(&cursor)) {
struct dma_fence **new_fences;
unsigned int count;
while (*num_fences)
dma_fence_put((*fences)[--(*num_fences)]);
count = cursor.num_fences + 1;
/* Eventually re-allocate the array */
new_fences = krealloc_array(*fences, count,
sizeof(void *),
GFP_KERNEL);
if (count && !new_fences) {
kfree(*fences);
*fences = NULL;
*num_fences = 0;
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
*fences = new_fences;
}
(*fences)[(*num_fences)++] = dma_fence_get(fence);
}
dma_resv_iter_end(&cursor);
return 0;
}
EXPORT_SYMBOL_GPL(dma_resv_get_fences);
/**
* dma_resv_get_singleton - Get a single fence for all the fences
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
* @fence: the resulting fence
*
* Get a single fence representing all the fences inside the resv object.
* Returns either 0 for success or -ENOMEM.
*
* Warning: This can't be used like this when adding the fence back to the resv
* object since that can lead to stack corruption when finalizing the
* dma_fence_array.
*
* Returns 0 on success and negative error values on failure.
*/
int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
struct dma_fence **fence)
{
struct dma_fence_array *array;
struct dma_fence **fences;
unsigned count;
int r;
r = dma_resv_get_fences(obj, usage, &count, &fences);
if (r)
return r;
if (count == 0) {
*fence = NULL;
return 0;
}
if (count == 1) {
*fence = fences[0];
kfree(fences);
return 0;
}
array = dma_fence_array_create(count, fences,
dma_fence_context_alloc(1),
1, false);
if (!array) {
while (count--)
dma_fence_put(fences[count]);
kfree(fences);
return -ENOMEM;
}
*fence = &array->base;
return 0;
}
EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
/**
* dma_resv_wait_timeout - Wait on reservation's objects fences
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
* @intr: if true, do interruptible wait
* @timeout: timeout value in jiffies or zero to return immediately
*
* Callers are not required to hold specific locks, but maybe hold
* dma_resv_lock() already
* RETURNS
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
* greater than zero on success.
*/
long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
bool intr, unsigned long timeout)
{
long ret = timeout ? timeout : 1;
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_iter_begin(&cursor, obj, usage);
dma_resv_for_each_fence_unlocked(&cursor, fence) {
ret = dma_fence_wait_timeout(fence, intr, ret);
if (ret <= 0) {
dma_resv_iter_end(&cursor);
return ret;
}
}
dma_resv_iter_end(&cursor);
return ret;
}
EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
/**
* dma_resv_set_deadline - Set a deadline on reservation's objects fences
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
* @deadline: the requested deadline (MONOTONIC)
*
* May be called without holding the dma_resv lock. Sets @deadline on
* all fences filtered by @usage.
*/
void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
ktime_t deadline)
{
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_iter_begin(&cursor, obj, usage);
dma_resv_for_each_fence_unlocked(&cursor, fence) {
dma_fence_set_deadline(fence, deadline);
}
dma_resv_iter_end(&cursor);
}
EXPORT_SYMBOL_GPL(dma_resv_set_deadline);
/**
* dma_resv_test_signaled - Test if a reservation object's fences have been
* signaled.
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
*
* Callers are not required to hold specific locks, but maybe hold
* dma_resv_lock() already.
*
* RETURNS
*
* True if all fences signaled, else false.
*/
bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
{
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_iter_begin(&cursor, obj, usage);
dma_resv_for_each_fence_unlocked(&cursor, fence) {
dma_resv_iter_end(&cursor);
return false;
}
dma_resv_iter_end(&cursor);
return true;
}
EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
/**
* dma_resv_describe - Dump description of the resv object into seq_file
* @obj: the reservation object
* @seq: the seq_file to dump the description into
*
* Dump a textual description of the fences inside an dma_resv object into the
* seq_file.
*/
void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
{
static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
seq_printf(seq, "\t%s fence:",
usage[dma_resv_iter_usage(&cursor)]);
dma_fence_describe(fence, seq);
}
}
EXPORT_SYMBOL_GPL(dma_resv_describe);
#if IS_ENABLED(CONFIG_LOCKDEP)
static int __init dma_resv_lockdep(void)
{
struct mm_struct *mm = mm_alloc();
struct ww_acquire_ctx ctx;
struct dma_resv obj;
struct address_space mapping;
int ret;
if (!mm)
return -ENOMEM;
dma_resv_init(&obj);
address_space_init_once(&mapping);
mmap_read_lock(mm);
ww_acquire_init(&ctx, &reservation_ww_class);
ret = dma_resv_lock(&obj, &ctx);
if (ret == -EDEADLK)
dma_resv_lock_slow(&obj, &ctx);
fs_reclaim_acquire(GFP_KERNEL);
/* for unmap_mapping_range on trylocked buffer objects in shrinkers */
i_mmap_lock_write(&mapping);
i_mmap_unlock_write(&mapping);
#ifdef CONFIG_MMU_NOTIFIER
lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
__dma_fence_might_wait();
lock_map_release(&__mmu_notifier_invalidate_range_start_map);
#else
__dma_fence_might_wait();
#endif
fs_reclaim_release(GFP_KERNEL);
ww_mutex_unlock(&obj.lock);
ww_acquire_fini(&ctx);
mmap_read_unlock(mm);
mmput(mm);
return 0;
}
subsys_initcall(dma_resv_lockdep);
#endif