linux/drivers/dma-buf/dma-resv.c
Christian König a25efb3863 dma-buf: add dma_fence_describe and dma_resv_describe v2
Add functions to dump dma_fence and dma_resv objects into a seq_file and
use them for printing the debugfs information.

v2: fix missing include reported by test robot.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211103081231.18578-2-christian.koenig@amd.com
2021-11-11 09:35:13 +01:00

734 lines
19 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>
#include <linux/seq_file.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.
*
* See struct dma_resv for more details.
*/
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 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_shared_fence(). This is validated
* when CONFIG_DEBUG_MUTEXES is enabled.
*
* 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 must be locked with dma_resv_lock(), and
* dma_resv_reserve_shared() has been called.
*
* See also &dma_resv.fence for a discussion of the semantics.
*/
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 exclusive fence to add
*
* Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
* Note that this function replaces all fences attached to @obj, see also
* &dma_resv.fence_excl for a discussion of the semantics.
*/
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_iter_restart_unlocked - restart the unlocked iterator
* @cursor: The dma_resv_iter object to restart
*
* Restart the unlocked iteration by initializing the cursor object.
*/
static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
{
cursor->seq = read_seqcount_begin(&cursor->obj->seq);
cursor->index = -1;
cursor->shared_count = 0;
if (cursor->all_fences) {
cursor->fences = dma_resv_shared_list(cursor->obj);
if (cursor->fences)
cursor->shared_count = cursor->fences->shared_count;
} else {
cursor->fences = NULL;
}
cursor->is_restarted = true;
}
/**
* dma_resv_iter_walk_unlocked - walk over fences in a dma_resv obj
* @cursor: cursor to record the current position
*
* Return all the fences in the dma_resv object which are not yet signaled.
* The returned fence has an extra local reference so will stay alive.
* If a concurrent modify is detected the whole iteration is started over again.
*/
static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
{
struct dma_resv *obj = cursor->obj;
do {
/* Drop the reference from the previous round */
dma_fence_put(cursor->fence);
if (cursor->index == -1) {
cursor->fence = dma_resv_excl_fence(obj);
cursor->index++;
if (!cursor->fence)
continue;
} else if (!cursor->fences ||
cursor->index >= cursor->shared_count) {
cursor->fence = NULL;
break;
} else {
struct dma_resv_list *fences = cursor->fences;
unsigned int idx = cursor->index++;
cursor->fence = rcu_dereference(fences->shared[idx]);
}
cursor->fence = dma_fence_get_rcu(cursor->fence);
if (!cursor->fence || !dma_fence_is_signaled(cursor->fence))
break;
} while (true);
}
/**
* dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
* @cursor: the cursor with the current position
*
* 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 (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
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
*
* 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 = read_seqcount_retry(&cursor->obj->seq, cursor->seq);
do {
if (restart)
dma_resv_iter_restart_unlocked(cursor);
dma_resv_iter_walk_unlocked(cursor);
restart = true;
} while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
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
*
* 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;
if (cursor->all_fences)
cursor->fences = dma_resv_shared_list(cursor->obj);
else
cursor->fences = NULL;
fence = dma_resv_excl_fence(cursor->obj);
if (!fence)
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)
{
unsigned int idx;
dma_resv_assert_held(cursor->obj);
cursor->is_restarted = false;
if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
return NULL;
idx = cursor->index++;
return rcu_dereference_protected(cursor->fences->shared[idx],
dma_resv_held(cursor->obj));
}
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, *excl;
dma_resv_assert_held(dst);
list = NULL;
excl = NULL;
dma_resv_iter_begin(&cursor, src, true);
dma_resv_for_each_fence_unlocked(&cursor, f) {
if (dma_resv_iter_is_restarted(&cursor)) {
dma_resv_list_free(list);
dma_fence_put(excl);
if (cursor.shared_count) {
list = dma_resv_list_alloc(cursor.shared_count);
if (!list) {
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
list->shared_count = 0;
} else {
list = NULL;
}
excl = NULL;
}
dma_fence_get(f);
if (dma_resv_iter_is_exclusive(&cursor))
excl = f;
else
RCU_INIT_POINTER(list->shared[list->shared_count++], f);
}
dma_resv_iter_end(&cursor);
write_seqcount_begin(&dst->seq);
excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
write_seqcount_end(&dst->seq);
dma_resv_list_free(list);
dma_fence_put(excl);
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
* @fence_excl: the returned exclusive fence (or NULL)
* @shared_count: the number of shared fences returned
* @shared: 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 **fence_excl,
unsigned int *shared_count, struct dma_fence ***shared)
{
struct dma_resv_iter cursor;
struct dma_fence *fence;
*shared_count = 0;
*shared = NULL;
if (fence_excl)
*fence_excl = NULL;
dma_resv_iter_begin(&cursor, obj, true);
dma_resv_for_each_fence_unlocked(&cursor, fence) {
if (dma_resv_iter_is_restarted(&cursor)) {
unsigned int count;
while (*shared_count)
dma_fence_put((*shared)[--(*shared_count)]);
if (fence_excl)
dma_fence_put(*fence_excl);
count = cursor.shared_count;
count += fence_excl ? 0 : 1;
/* Eventually re-allocate the array */
*shared = krealloc_array(*shared, count,
sizeof(void *),
GFP_KERNEL);
if (count && !*shared) {
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
}
dma_fence_get(fence);
if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
*fence_excl = fence;
else
(*shared)[(*shared_count)++] = fence;
}
dma_resv_iter_end(&cursor);
return 0;
}
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;
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_iter_begin(&cursor, obj, wait_all);
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_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_resv_iter cursor;
struct dma_fence *fence;
dma_resv_iter_begin(&cursor, obj, test_all);
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)
{
struct dma_resv_iter cursor;
struct dma_fence *fence;
dma_resv_for_each_fence(&cursor, obj, true, fence) {
seq_printf(seq, "\t%s fence:",
dma_resv_iter_is_exclusive(&cursor) ?
"Exclusive" : "Shared");
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