1 files changed, 650 insertions, 0 deletions

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
new file mode 100644
index 000000000000..42a8f3f11681
--- /dev/null
+++ b/drivers/dma-buf/dma-resv.c
@@ -0,0 +1,650 @@
+/*
+ * 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>
+
+/**
+ * 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);
+
+struct lock_class_key reservation_seqcount_class;
+EXPORT_SYMBOL(reservation_seqcount_class);
+
+const char reservation_seqcount_string[] = "reservation_seqcount";
+EXPORT_SYMBOL(reservation_seqcount_string);
+
+/**
+ * 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(offsetof(typeof(*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_init(&obj->seq, reservation_seqcount_string,
+			&reservation_seqcount_class);
+	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_get_list(obj);
+
+	if (old && old->shared_max) {
+		if ((old->shared_count + num_fences) <= old->shared_max)
+			return 0;
+		else
+			max = max(old->shared_count + num_fences,
+				  old->shared_max * 2);
+	} else {
+		max = 4;
+	}
+
+	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);
+
+/**
+ * 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_get_list(obj);
+	count = fobj->shared_count;
+
+	preempt_disable();
+	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);
+	preempt_enable();
+	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_get_excl(obj);
+	struct dma_resv_list *old;
+	u32 i = 0;
+
+	dma_resv_assert_held(obj);
+
+	old = dma_resv_get_list(obj);
+	if (old)
+		i = old->shared_count;
+
+	if (fence)
+		dma_fence_get(fence);
+
+	preempt_disable();
+	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);
+	preempt_enable();
+
+	/* 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 i;
+
+	dma_resv_assert_held(dst);
+
+	rcu_read_lock();
+	src_list = rcu_dereference(src->fence);
+
+retry:
+	if (src_list) {
+		unsigned 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 = rcu_dereference(src->fence);
+		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 *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 = rcu_dereference(src->fence);
+				goto retry;
+			}
+
+			if (dma_fence_is_signaled(fence)) {
+				dma_fence_put(fence);
+				continue;
+			}
+
+			rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
+		}
+	} else {
+		dst_list = NULL;
+	}
+
+	new = dma_fence_get_rcu_safe(&src->fence_excl);
+	rcu_read_unlock();
+
+	src_list = dma_resv_get_list(dst);
+	old = dma_resv_get_excl(dst);
+
+	preempt_disable();
+	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);
+	preempt_enable();
+
+	dma_resv_list_free(src_list);
+	dma_fence_put(old);
+
+	return 0;
+}
+EXPORT_SYMBOL(dma_resv_copy_fences);
+
+/**
+ * dma_resv_get_fences_rcu - 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_rcu(struct dma_resv *obj,
+			    struct dma_fence **pfence_excl,
+			    unsigned *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 = 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;
+
+		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_rcu);
+
+/**
+ * dma_resv_wait_timeout_rcu - 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
+ *
+ * RETURNS
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
+ * greater than zer on success.
+ */
+long dma_resv_wait_timeout_rcu(struct dma_resv *obj,
+			       bool wait_all, bool intr,
+			       unsigned long timeout)
+{
+	struct dma_fence *fence;
+	unsigned seq, 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);
+	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 = 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]);
+
+			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_rcu);
+
+
+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_rcu - 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
+ *
+ * RETURNS
+ * true if all fences signaled, else false
+ */
+bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all)
+{
+	unsigned seq, shared_count;
+	int ret;
+
+	rcu_read_lock();
+retry:
+	ret = true;
+	shared_count = 0;
+	seq = read_seqcount_begin(&obj->seq);
+
+	if (test_all) {
+		unsigned i;
+
+		struct dma_resv_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]);
+
+			ret = dma_resv_test_signaled_single(fence);
+			if (ret < 0)
+				goto 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 = dma_resv_test_signaled_single(fence_excl);
+			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_rcu);