linux/drivers/dma-buf/dma-resv.c
Christian König 9d38814d1e dma-buf: fix dma_resv_test_signaled test_all handling v2
As the name implies if testing all fences is requested we
should indeed test all fences and not skip the exclusive
one because we see shared ones.

v2: fix logic once more

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210702111642.17259-3-christian.koenig@amd.com
2021-07-08 14:59:08 +02:00

700 lines
17 KiB
C

// 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/export.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/mmu_notifier.h>
/**
* DOC: Reservation Object Overview
*
* The reservation object provides a mechanism to manage shared and
* exclusive fences associated with a buffer. A reservation object
* can have attached one exclusive fence (normally associated with
* write operations) or N shared fences (read operations). The RCU
* mechanism is used to protect read access to fences from locked
* write-side updates.
*/
DEFINE_WD_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
/**
* dma_resv_list_alloc - allocate fence list
* @shared_max: number of fences we need space for
*
* Allocate a new dma_resv_list and make sure to correctly initialize
* shared_max.
*/
static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
{
struct dma_resv_list *list;
list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
if (!list)
return NULL;
list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
sizeof(*list->shared);
return list;
}
/**
* dma_resv_list_free - free fence list
* @list: list to free
*
* 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->shared_count; ++i)
dma_fence_put(rcu_dereference_protected(list->shared[i], true));
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);
seqcount_ww_mutex_init(&obj->seq, &obj->lock);
RCU_INIT_POINTER(obj->fence, NULL);
RCU_INIT_POINTER(obj->fence_excl, 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)
{
struct dma_resv_list *fobj;
struct dma_fence *excl;
/*
* This object should be dead and all references must have
* been released to it, so no need to be protected with rcu.
*/
excl = rcu_dereference_protected(obj->fence_excl, 1);
if (excl)
dma_fence_put(excl);
fobj = rcu_dereference_protected(obj->fence, 1);
dma_resv_list_free(fobj);
ww_mutex_destroy(&obj->lock);
}
EXPORT_SYMBOL(dma_resv_fini);
/**
* dma_resv_reserve_shared - Reserve space to add shared fences to
* a dma_resv.
* @obj: reservation object
* @num_fences: number of fences we want to add
*
* Should be called before dma_resv_add_shared_fence(). Must
* be called with obj->lock held.
*
* RETURNS
* Zero for success, or -errno
*/
int dma_resv_reserve_shared(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_shared_list(obj);
if (old && old->shared_max) {
if ((old->shared_count + num_fences) <= old->shared_max)
return 0;
max = max(old->shared_count + num_fences, old->shared_max * 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->shared_count : 0); ++i) {
struct dma_fence *fence;
fence = rcu_dereference_protected(old->shared[i],
dma_resv_held(obj));
if (dma_fence_is_signaled(fence))
RCU_INIT_POINTER(new->shared[--k], fence);
else
RCU_INIT_POINTER(new->shared[j++], fence);
}
new->shared_count = 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) shared 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->fence, 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->shared[i],
dma_resv_held(obj));
dma_fence_put(fence);
}
kfree_rcu(old, rcu);
return 0;
}
EXPORT_SYMBOL(dma_resv_reserve_shared);
#ifdef CONFIG_DEBUG_MUTEXES
/**
* dma_resv_reset_shared_max - reset shared fences for debugging
* @obj: the dma_resv object to reset
*
* Reset the number of pre-reserved shared slots to test that drivers do
* correct slot allocation using dma_resv_reserve_shared(). See also
* &dma_resv_list.shared_max.
*/
void dma_resv_reset_shared_max(struct dma_resv *obj)
{
struct dma_resv_list *fences = dma_resv_shared_list(obj);
dma_resv_assert_held(obj);
/* Test shared fence slot reservation */
if (fences)
fences->shared_max = fences->shared_count;
}
EXPORT_SYMBOL(dma_resv_reset_shared_max);
#endif
/**
* dma_resv_add_shared_fence - Add a fence to a shared slot
* @obj: the reservation object
* @fence: the shared fence to add
*
* Add a fence to a shared slot, obj->lock must be held, and
* dma_resv_reserve_shared() has been called.
*/
void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
{
struct dma_resv_list *fobj;
struct dma_fence *old;
unsigned int i, count;
dma_fence_get(fence);
dma_resv_assert_held(obj);
fobj = dma_resv_shared_list(obj);
count = fobj->shared_count;
write_seqcount_begin(&obj->seq);
for (i = 0; i < count; ++i) {
old = rcu_dereference_protected(fobj->shared[i],
dma_resv_held(obj));
if (old->context == fence->context ||
dma_fence_is_signaled(old))
goto replace;
}
BUG_ON(fobj->shared_count >= fobj->shared_max);
old = NULL;
count++;
replace:
RCU_INIT_POINTER(fobj->shared[i], fence);
/* pointer update must be visible before we extend the shared_count */
smp_store_mb(fobj->shared_count, count);
write_seqcount_end(&obj->seq);
dma_fence_put(old);
}
EXPORT_SYMBOL(dma_resv_add_shared_fence);
/**
* dma_resv_add_excl_fence - Add an exclusive fence.
* @obj: the reservation object
* @fence: the shared fence to add
*
* Add a fence to the exclusive slot. The obj->lock must be held.
*/
void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
{
struct dma_fence *old_fence = dma_resv_excl_fence(obj);
struct dma_resv_list *old;
u32 i = 0;
dma_resv_assert_held(obj);
old = dma_resv_shared_list(obj);
if (old)
i = old->shared_count;
if (fence)
dma_fence_get(fence);
write_seqcount_begin(&obj->seq);
/* write_seqcount_begin provides the necessary memory barrier */
RCU_INIT_POINTER(obj->fence_excl, fence);
if (old)
old->shared_count = 0;
write_seqcount_end(&obj->seq);
/* inplace update, no shared fences */
while (i--)
dma_fence_put(rcu_dereference_protected(old->shared[i],
dma_resv_held(obj)));
dma_fence_put(old_fence);
}
EXPORT_SYMBOL(dma_resv_add_excl_fence);
/**
* 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_list *src_list, *dst_list;
struct dma_fence *old, *new;
unsigned int i;
dma_resv_assert_held(dst);
rcu_read_lock();
src_list = dma_resv_shared_list(src);
retry:
if (src_list) {
unsigned int shared_count = src_list->shared_count;
rcu_read_unlock();
dst_list = dma_resv_list_alloc(shared_count);
if (!dst_list)
return -ENOMEM;
rcu_read_lock();
src_list = dma_resv_shared_list(src);
if (!src_list || src_list->shared_count > shared_count) {
kfree(dst_list);
goto retry;
}
dst_list->shared_count = 0;
for (i = 0; i < src_list->shared_count; ++i) {
struct dma_fence __rcu **dst;
struct dma_fence *fence;
fence = rcu_dereference(src_list->shared[i]);
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
&fence->flags))
continue;
if (!dma_fence_get_rcu(fence)) {
dma_resv_list_free(dst_list);
src_list = dma_resv_shared_list(src);
goto retry;
}
if (dma_fence_is_signaled(fence)) {
dma_fence_put(fence);
continue;
}
dst = &dst_list->shared[dst_list->shared_count++];
rcu_assign_pointer(*dst, fence);
}
} else {
dst_list = NULL;
}
new = dma_fence_get_rcu_safe(&src->fence_excl);
rcu_read_unlock();
src_list = dma_resv_shared_list(dst);
old = dma_resv_excl_fence(dst);
write_seqcount_begin(&dst->seq);
/* write_seqcount_begin provides the necessary memory barrier */
RCU_INIT_POINTER(dst->fence_excl, new);
RCU_INIT_POINTER(dst->fence, dst_list);
write_seqcount_end(&dst->seq);
dma_resv_list_free(src_list);
dma_fence_put(old);
return 0;
}
EXPORT_SYMBOL(dma_resv_copy_fences);
/**
* dma_resv_get_fences - Get an object's shared and exclusive
* fences without update side lock held
* @obj: the reservation object
* @pfence_excl: the returned exclusive fence (or NULL)
* @pshared_count: the number of shared fences returned
* @pshared: the array of shared fence ptrs returned (array is krealloc'd to
* the required size, and must be freed by caller)
*
* Retrieve all fences from the reservation object. If the pointer for the
* exclusive fence is not specified the fence is put into the array of the
* shared fences as well. Returns either zero or -ENOMEM.
*/
int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
unsigned int *pshared_count,
struct dma_fence ***pshared)
{
struct dma_fence **shared = NULL;
struct dma_fence *fence_excl;
unsigned int shared_count;
int ret = 1;
do {
struct dma_resv_list *fobj;
unsigned int i, seq;
size_t sz = 0;
shared_count = i = 0;
rcu_read_lock();
seq = read_seqcount_begin(&obj->seq);
fence_excl = dma_resv_excl_fence(obj);
if (fence_excl && !dma_fence_get_rcu(fence_excl))
goto unlock;
fobj = dma_resv_shared_list(obj);
if (fobj)
sz += sizeof(*shared) * fobj->shared_max;
if (!pfence_excl && fence_excl)
sz += sizeof(*shared);
if (sz) {
struct dma_fence **nshared;
nshared = krealloc(shared, sz,
GFP_NOWAIT | __GFP_NOWARN);
if (!nshared) {
rcu_read_unlock();
dma_fence_put(fence_excl);
fence_excl = NULL;
nshared = krealloc(shared, sz, GFP_KERNEL);
if (nshared) {
shared = nshared;
continue;
}
ret = -ENOMEM;
break;
}
shared = nshared;
shared_count = fobj ? fobj->shared_count : 0;
for (i = 0; i < shared_count; ++i) {
shared[i] = rcu_dereference(fobj->shared[i]);
if (!dma_fence_get_rcu(shared[i]))
break;
}
}
if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
while (i--)
dma_fence_put(shared[i]);
dma_fence_put(fence_excl);
goto unlock;
}
ret = 0;
unlock:
rcu_read_unlock();
} while (ret);
if (pfence_excl)
*pfence_excl = fence_excl;
else if (fence_excl)
shared[shared_count++] = fence_excl;
if (!shared_count) {
kfree(shared);
shared = NULL;
}
*pshared_count = shared_count;
*pshared = shared;
return ret;
}
EXPORT_SYMBOL_GPL(dma_resv_get_fences);
/**
* dma_resv_wait_timeout - Wait on reservation's objects
* shared and/or exclusive fences.
* @obj: the reservation object
* @wait_all: if true, wait on all fences, else wait on just exclusive fence
* @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 zer on success.
*/
long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
unsigned long timeout)
{
long ret = timeout ? timeout : 1;
unsigned int seq, shared_count;
struct dma_fence *fence;
int i;
retry:
shared_count = 0;
seq = read_seqcount_begin(&obj->seq);
rcu_read_lock();
i = -1;
fence = dma_resv_excl_fence(obj);
if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
if (!dma_fence_get_rcu(fence))
goto unlock_retry;
if (dma_fence_is_signaled(fence)) {
dma_fence_put(fence);
fence = NULL;
}
} else {
fence = NULL;
}
if (wait_all) {
struct dma_resv_list *fobj = dma_resv_shared_list(obj);
if (fobj)
shared_count = fobj->shared_count;
for (i = 0; !fence && i < shared_count; ++i) {
struct dma_fence *lfence;
lfence = rcu_dereference(fobj->shared[i]);
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
&lfence->flags))
continue;
if (!dma_fence_get_rcu(lfence))
goto unlock_retry;
if (dma_fence_is_signaled(lfence)) {
dma_fence_put(lfence);
continue;
}
fence = lfence;
break;
}
}
rcu_read_unlock();
if (fence) {
if (read_seqcount_retry(&obj->seq, seq)) {
dma_fence_put(fence);
goto retry;
}
ret = dma_fence_wait_timeout(fence, intr, ret);
dma_fence_put(fence);
if (ret > 0 && wait_all && (i + 1 < shared_count))
goto retry;
}
return ret;
unlock_retry:
rcu_read_unlock();
goto retry;
}
EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
{
struct dma_fence *fence, *lfence = passed_fence;
int ret = 1;
if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
fence = dma_fence_get_rcu(lfence);
if (!fence)
return -1;
ret = !!dma_fence_is_signaled(fence);
dma_fence_put(fence);
}
return ret;
}
/**
* dma_resv_test_signaled - Test if a reservation object's fences have been
* signaled.
* @obj: the reservation object
* @test_all: if true, test all fences, otherwise only test the exclusive
* fence
*
* 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, bool test_all)
{
struct dma_fence *fence;
unsigned int seq;
int ret;
rcu_read_lock();
retry:
ret = true;
seq = read_seqcount_begin(&obj->seq);
if (test_all) {
struct dma_resv_list *fobj = dma_resv_shared_list(obj);
unsigned int i, shared_count;
shared_count = fobj ? fobj->shared_count : 0;
for (i = 0; i < shared_count; ++i) {
fence = rcu_dereference(fobj->shared[i]);
ret = dma_resv_test_signaled_single(fence);
if (ret < 0)
goto retry;
else if (!ret)
break;
}
}
fence = dma_resv_excl_fence(obj);
if (ret && fence) {
ret = dma_resv_test_signaled_single(fence);
if (ret < 0)
goto retry;
}
if (read_seqcount_retry(&obj->seq, seq))
goto retry;
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
#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