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(a)amd.com>
---
drivers/dma-buf/dma-buf.c | 31 ++-------
drivers/dma-buf/reservation.c | 82 ++++++++----------------
include/linux/reservation.h | 115 +++++++++++++++++++++-------------
3 files changed, 101 insertions(+), 127 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f45bfb29ef96..67510f2be8bc 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -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",
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index ad6775b32a73..8fcaddffd5d4 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -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 @@ int reservation_object_copy_fences(struct reservation_object *dst,
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 @@ int reservation_object_copy_fences(struct reservation_object *dst,
if (!dma_fence_get_rcu(fence)) {
reservation_object_list_free(dst_list);
- src_list = rcu_dereference(src->fence);
goto retry;
}
@@ -367,7 +364,10 @@ int reservation_object_copy_fences(struct reservation_object *dst,
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 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
}
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 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
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 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
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();
diff --git a/include/linux/reservation.h b/include/linux/reservation.h
index 56b782fec49b..044a5cd4af50 100644
--- a/include/linux/reservation.h
+++ b/include/linux/reservation.h
@@ -81,6 +81,51 @@ 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_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_get_list - get the reservation object's
* shared fence list, with update-side lock held
@@ -96,6 +141,31 @@ 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_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,
--
2.17.1
