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dma-buf: add reservation_object_fences helper 

Add a new helper to get a consistent set of pointers from the reservation
object. While at it group all access helpers together in the header file.

v2: correctly return shared_count as well

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/322378/?series=64837&rev=1
alistair/sunxi64-5.4-dsi
Christian König 2019-08-06 14:19:33 +02:00
parent 0e2f733add
commit 67c97fb79a
3 changed files with 101 additions and 127 deletions
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31
drivers/dma-buf/dma-buf.c
View File

@ -199,7 +199,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
struct reservation_object_list *fobj;
struct dma_fence *fence_excl;
__poll_t events;
unsigned shared_count, seq;
unsigned shared_count;
dmabuf = file->private_data;
if (!dmabuf || !dmabuf->resv)
@ -213,21 +213,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
if (!events)
return 0;
retry:
seq = read_seqcount_begin(&resv->seq);
rcu_read_lock();
fobj = rcu_dereference(resv->fence);
if (fobj)
shared_count = fobj->shared_count;
else
shared_count = 0;
fence_excl = rcu_dereference(resv->fence_excl);
if (read_seqcount_retry(&resv->seq, seq)) {
rcu_read_unlock();
goto retry;
}
reservation_object_fences(resv, &fence_excl, &fobj, &shared_count);
if (fence_excl && (!(events & EPOLLOUT) || shared_count == 0)) {
struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;
__poll_t pevents = EPOLLIN;
@ -1157,7 +1144,6 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
struct reservation_object *robj;
struct reservation_object_list *fobj;
struct dma_fence *fence;
unsigned seq;
int count = 0, attach_count, shared_count, i;
size_t size = 0;
@ -1188,16 +1174,9 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
buf_obj->name ?: "");
robj = buf_obj->resv;
while (true) {
seq = read_seqcount_begin(&robj->seq);
rcu_read_lock();
fobj = rcu_dereference(robj->fence);
shared_count = fobj ? fobj->shared_count : 0;
fence = rcu_dereference(robj->fence_excl);
if (!read_seqcount_retry(&robj->seq, seq))
break;
rcu_read_unlock();
}
rcu_read_lock();
reservation_object_fences(robj, &fence, &fobj, &shared_count);
rcu_read_unlock();
if (fence)
seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",

82
drivers/dma-buf/reservation.c
View File

@ -317,17 +317,15 @@ int reservation_object_copy_fences(struct reservation_object *dst,
{
struct reservation_object_list *src_list, *dst_list;
struct dma_fence *old, *new;
unsigned i;
unsigned int i, shared_count;
reservation_object_assert_held(dst);
rcu_read_lock();
src_list = rcu_dereference(src->fence);
retry:
if (src_list) {
unsigned shared_count = src_list->shared_count;
reservation_object_fences(src, &new, &src_list, &shared_count);
if (shared_count) {
rcu_read_unlock();
dst_list = reservation_object_list_alloc(shared_count);
@ -335,14 +333,14 @@ retry:
return -ENOMEM;
rcu_read_lock();
src_list = rcu_dereference(src->fence);
if (!src_list || src_list->shared_count > shared_count) {
reservation_object_fences(src, &new, &src_list, &shared_count);
if (!src_list || shared_count > dst_list->shared_max) {
kfree(dst_list);
goto retry;
}
dst_list->shared_count = 0;
for (i = 0; i < src_list->shared_count; ++i) {
for (i = 0; i < shared_count; ++i) {
struct dma_fence *fence;
fence = rcu_dereference(src_list->shared[i]);
@ -352,7 +350,6 @@ retry:
if (!dma_fence_get_rcu(fence)) {
reservation_object_list_free(dst_list);
src_list = rcu_dereference(src->fence);
goto retry;
}
@ -367,7 +364,10 @@ retry:
dst_list = NULL;
}
new = dma_fence_get_rcu_safe(&src->fence_excl);
if (new && !dma_fence_get_rcu(new)) {
reservation_object_list_free(dst_list);
goto retry;
}
rcu_read_unlock();
src_list = reservation_object_get_list(dst);
@ -413,19 +413,18 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
do {
struct reservation_object_list *fobj;
unsigned int i, seq;
unsigned int i;
size_t sz = 0;
shared_count = i = 0;
i = 0;
rcu_read_lock();
seq = read_seqcount_begin(&obj->seq);
reservation_object_fences(obj, &fence_excl, &fobj,
&shared_count);
fence_excl = rcu_dereference(obj->fence_excl);
if (fence_excl && !dma_fence_get_rcu(fence_excl))
goto unlock;
fobj = rcu_dereference(obj->fence);
if (fobj)
sz += sizeof(*shared) * fobj->shared_max;
@ -453,7 +452,6 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
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]))
@ -461,7 +459,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
}
}
if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
if (i != shared_count) {
while (i--)
dma_fence_put(shared[i]);
dma_fence_put(fence_excl);
@ -505,18 +503,17 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
bool wait_all, bool intr,
unsigned long timeout)
{
struct reservation_object_list *fobj;
struct dma_fence *fence;
unsigned seq, shared_count;
unsigned shared_count;
long ret = timeout ? timeout : 1;
int i;
retry:
shared_count = 0;
seq = read_seqcount_begin(&obj->seq);
rcu_read_lock();
i = -1;
fence = rcu_dereference(obj->fence_excl);
reservation_object_fences(obj, &fence, &fobj, &shared_count);
if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
if (!dma_fence_get_rcu(fence))
goto unlock_retry;
@ -531,12 +528,6 @@ retry:
}
if (wait_all) {
struct reservation_object_list *fobj =
rcu_dereference(obj->fence);
if (fobj)
shared_count = fobj->shared_count;
for (i = 0; !fence && i < shared_count; ++i) {
struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
@ -559,11 +550,6 @@ retry:
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))
@ -608,24 +594,19 @@ reservation_object_test_signaled_single(struct dma_fence *passed_fence)
bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
bool test_all)
{
unsigned seq, shared_count;
struct reservation_object_list *fobj;
struct dma_fence *fence_excl;
unsigned shared_count;
int ret;
rcu_read_lock();
retry:
ret = true;
shared_count = 0;
seq = read_seqcount_begin(&obj->seq);
reservation_object_fences(obj, &fence_excl, &fobj, &shared_count);
if (test_all) {
unsigned i;
struct reservation_object_list *fobj =
rcu_dereference(obj->fence);
if (fobj)
shared_count = fobj->shared_count;
for (i = 0; i < shared_count; ++i) {
struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
@ -635,23 +616,12 @@ retry:
else if (!ret)
break;
}
if (read_seqcount_retry(&obj->seq, seq))
goto retry;
}
if (!shared_count) {
struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
if (fence_excl) {
ret = reservation_object_test_signaled_single(
fence_excl);
if (ret < 0)
goto retry;
if (read_seqcount_retry(&obj->seq, seq))
goto retry;
}
if (!shared_count && fence_excl) {
ret = reservation_object_test_signaled_single(fence_excl);
if (ret < 0)
goto retry;
}
rcu_read_unlock();

115
include/linux/reservation.h
View File

@ -81,6 +81,25 @@ struct reservation_object {
#define reservation_object_assert_held(obj) \
lockdep_assert_held(&(obj)->lock.base)
/**
* reservation_object_get_excl - get the reservation object's
* exclusive fence, with update-side lock held
* @obj: the reservation object
*
* Returns the exclusive fence (if any). Does NOT take a
* reference. Writers must hold obj->lock, readers may only
* hold a RCU read side lock.
*
* RETURNS
* The exclusive fence or NULL
*/
static inline struct dma_fence *
reservation_object_get_excl(struct reservation_object *obj)
{
return rcu_dereference_protected(obj->fence_excl,
reservation_object_held(obj));
}
/**
* reservation_object_get_list - get the reservation object's
* shared fence list, with update-side lock held
@ -96,6 +115,57 @@ reservation_object_get_list(struct reservation_object *obj)
reservation_object_held(obj));
}
/**
* reservation_object_fences - read consistent fence pointers
* @obj: reservation object where we get the fences from
* @excl: pointer for the exclusive fence
* @list: pointer for the shared fence list
*
* Make sure we have a consisten exclusive fence and shared fence list.
* Must be called with rcu read side lock held.
*/
static inline void
reservation_object_fences(struct reservation_object *obj,
struct dma_fence **excl,
struct reservation_object_list **list,
u32 *shared_count)
{
unsigned int seq;
do {
seq = read_seqcount_begin(&obj->seq);
*excl = rcu_dereference(obj->fence_excl);
*list = rcu_dereference(obj->fence);
*shared_count = *list ? (*list)->shared_count : 0;
} while (read_seqcount_retry(&obj->seq, seq));
}
/**
* reservation_object_get_excl_rcu - get the reservation object's
* exclusive fence, without lock held.
* @obj: the reservation object
*
* If there is an exclusive fence, this atomically increments it's
* reference count and returns it.
*
* RETURNS
* The exclusive fence or NULL if none
*/
static inline struct dma_fence *
reservation_object_get_excl_rcu(struct reservation_object *obj)
{
struct dma_fence *fence;
if (!rcu_access_pointer(obj->fence_excl))
return NULL;
rcu_read_lock();
fence = dma_fence_get_rcu_safe(&obj->fence_excl);
rcu_read_unlock();
return fence;
}
/**
* reservation_object_lock - lock the reservation object
* @obj: the reservation object
@ -239,51 +309,6 @@ reservation_object_unlock(struct reservation_object *obj)
ww_mutex_unlock(&obj->lock);
}
/**
* reservation_object_get_excl - get the reservation object's
* exclusive fence, with update-side lock held
* @obj: the reservation object
*
* Returns the exclusive fence (if any). Does NOT take a
* reference. Writers must hold obj->lock, readers may only
* hold a RCU read side lock.
*
* RETURNS
* The exclusive fence or NULL
*/
static inline struct dma_fence *
reservation_object_get_excl(struct reservation_object *obj)
{
return rcu_dereference_protected(obj->fence_excl,
reservation_object_held(obj));
}
/**
* reservation_object_get_excl_rcu - get the reservation object's
* exclusive fence, without lock held.
* @obj: the reservation object
*
* If there is an exclusive fence, this atomically increments it's
* reference count and returns it.
*
* RETURNS
* The exclusive fence or NULL if none
*/
static inline struct dma_fence *
reservation_object_get_excl_rcu(struct reservation_object *obj)
{
struct dma_fence *fence;
if (!rcu_access_pointer(obj->fence_excl))
return NULL;
rcu_read_lock();
fence = dma_fence_get_rcu_safe(&obj->fence_excl);
rcu_read_unlock();
return fence;
}
void reservation_object_init(struct reservation_object *obj);
void reservation_object_fini(struct reservation_object *obj);
int reservation_object_reserve_shared(struct reservation_object *obj,