7 files changed, 915 insertions, 2 deletions

diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index ac61ebd92875..e634657efb52 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -129,6 +129,8 @@ X!Edrivers/base/interface.c
      </sect1>
      <sect1><title>Device Drivers DMA Management</title>
 !Edrivers/dma-buf/dma-buf.c
+!Edrivers/dma-buf/fence.c
+!Iinclude/linux/fence.h
 !Iinclude/linux/reservation.h
 !Edrivers/base/dma-coherent.c
 !Edrivers/base/dma-mapping.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 2eefee768d46..65c8f534b22f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2901,7 +2901,7 @@ L:	linux-media@vger.kernel.org
 L:      dri-devel@lists.freedesktop.org
 L:      linaro-mm-sig@lists.linaro.org
 F:      drivers/dma-buf/
-F:      include/linux/dma-buf* include/linux/reservation.h
+F:      include/linux/dma-buf* include/linux/reservation.h include/linux/fence.h
 F:      Documentation/dma-buf-sharing.txt
 T:      git git://git.linaro.org/people/sumitsemwal/linux-dma-buf.git
 
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 23b8726962af..00e13ce5cbbd 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -208,6 +208,15 @@ config DMA_SHARED_BUFFER
           APIs extension; the file's descriptor can then be passed on to other
           driver.
 
+config FENCE_TRACE
+        bool "Enable verbose FENCE_TRACE messages"
+        depends on DMA_SHARED_BUFFER
+        help
+          Enable the FENCE_TRACE printks. This will add extra
+          spam to the console log, but will make it easier to diagnose
+          lockup related problems for dma-buffers shared across multiple
+          devices.
+
 config DMA_CMA
         bool "DMA Contiguous Memory Allocator"
         depends on HAVE_DMA_CONTIGUOUS && CMA
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 4a4f4c9bacd0..d7825bfe630e 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -1 +1 @@
-obj-y := dma-buf.o reservation.o
+obj-y := dma-buf.o fence.o reservation.o
diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
new file mode 100644
index 000000000000..948bf00d955e
--- /dev/null
+++ b/drivers/dma-buf/fence.c
@@ -0,0 +1,431 @@
+/*
+ * Fence mechanism for dma-buf and to allow for asynchronous dma access
+ *
+ * Copyright (C) 2012 Canonical Ltd
+ * Copyright (C) 2012 Texas Instruments
+ *
+ * Authors:
+ * Rob Clark <robdclark@gmail.com>
+ * Maarten Lankhorst <maarten.lankhorst@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/atomic.h>
+#include <linux/fence.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/fence.h>
+
+EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on);
+EXPORT_TRACEPOINT_SYMBOL(fence_emit);
+
+/**
+ * fence context counter: each execution context should have its own
+ * fence context, this allows checking if fences belong to the same
+ * context or not. One device can have multiple separate contexts,
+ * and they're used if some engine can run independently of another.
+ */
+static atomic_t fence_context_counter = ATOMIC_INIT(0);
+
+/**
+ * fence_context_alloc - allocate an array of fence contexts
+ * @num:        [in]    amount of contexts to allocate
+ *
+ * This function will return the first index of the number of fences allocated.
+ * The fence context is used for setting fence->context to a unique number.
+ */
+unsigned fence_context_alloc(unsigned num)
+{
+        BUG_ON(!num);
+        return atomic_add_return(num, &fence_context_counter) - num;
+}
+EXPORT_SYMBOL(fence_context_alloc);
+
+/**
+ * fence_signal_locked - signal completion of a fence
+ * @fence: the fence to signal
+ *
+ * Signal completion for software callbacks on a fence, this will unblock
+ * fence_wait() calls and run all the callbacks added with
+ * fence_add_callback(). Can be called multiple times, but since a fence
+ * can only go from unsignaled to signaled state, it will only be effective
+ * the first time.
+ *
+ * Unlike fence_signal, this function must be called with fence->lock held.
+ */
+int fence_signal_locked(struct fence *fence)
+{
+        struct fence_cb *cur, *tmp;
+        int ret = 0;
+
+        if (WARN_ON(!fence))
+                return -EINVAL;
+
+        if (!ktime_to_ns(fence->timestamp)) {
+                fence->timestamp = ktime_get();
+                smp_mb__before_atomic();
+        }
+
+        if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+                ret = -EINVAL;
+
+                /*
+                 * we might have raced with the unlocked fence_signal,
+                 * still run through all callbacks
+                 */
+        } else
+                trace_fence_signaled(fence);
+
+        list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
+                list_del_init(&cur->node);
+                cur->func(fence, cur);
+        }
+        return ret;
+}
+EXPORT_SYMBOL(fence_signal_locked);
+
+/**
+ * fence_signal - signal completion of a fence
+ * @fence: the fence to signal
+ *
+ * Signal completion for software callbacks on a fence, this will unblock
+ * fence_wait() calls and run all the callbacks added with
+ * fence_add_callback(). Can be called multiple times, but since a fence
+ * can only go from unsignaled to signaled state, it will only be effective
+ * the first time.
+ */
+int fence_signal(struct fence *fence)
+{
+        unsigned long flags;
+
+        if (!fence)
+                return -EINVAL;
+
+        if (!ktime_to_ns(fence->timestamp)) {
+                fence->timestamp = ktime_get();
+                smp_mb__before_atomic();
+        }
+
+        if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                return -EINVAL;
+
+        trace_fence_signaled(fence);
+
+        if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
+                struct fence_cb *cur, *tmp;
+
+                spin_lock_irqsave(fence->lock, flags);
+                list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
+                        list_del_init(&cur->node);
+                        cur->func(fence, cur);
+                }
+                spin_unlock_irqrestore(fence->lock, flags);
+        }
+        return 0;
+}
+EXPORT_SYMBOL(fence_signal);
+
+/**
+ * fence_wait_timeout - sleep until the fence gets signaled
+ * or until timeout elapses
+ * @fence:      [in]    the fence to wait on
+ * @intr:       [in]    if true, do an interruptible wait
+ * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ *
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
+ * remaining timeout in jiffies on success. Other error values may be
+ * returned on custom implementations.
+ *
+ * Performs a synchronous wait on this fence. It is assumed the caller
+ * directly or indirectly (buf-mgr between reservation and committing)
+ * holds a reference to the fence, otherwise the fence might be
+ * freed before return, resulting in undefined behavior.
+ */
+signed long
+fence_wait_timeout(struct fence *fence, bool intr, signed long timeout)
+{
+        signed long ret;
+
+        if (WARN_ON(timeout < 0))
+                return -EINVAL;
+
+        trace_fence_wait_start(fence);
+        ret = fence->ops->wait(fence, intr, timeout);
+        trace_fence_wait_end(fence);
+        return ret;
+}
+EXPORT_SYMBOL(fence_wait_timeout);
+
+void fence_release(struct kref *kref)
+{
+        struct fence *fence =
+                        container_of(kref, struct fence, refcount);
+
+        trace_fence_destroy(fence);
+
+        BUG_ON(!list_empty(&fence->cb_list));
+
+        if (fence->ops->release)
+                fence->ops->release(fence);
+        else
+                fence_free(fence);
+}
+EXPORT_SYMBOL(fence_release);
+
+void fence_free(struct fence *fence)
+{
+        kfree(fence);
+}
+EXPORT_SYMBOL(fence_free);
+
+/**
+ * fence_enable_sw_signaling - enable signaling on fence
+ * @fence:      [in]    the fence to enable
+ *
+ * this will request for sw signaling to be enabled, to make the fence
+ * complete as soon as possible
+ */
+void fence_enable_sw_signaling(struct fence *fence)
+{
+        unsigned long flags;
+
+        if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) &&
+            !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+                trace_fence_enable_signal(fence);
+
+                spin_lock_irqsave(fence->lock, flags);
+
+                if (!fence->ops->enable_signaling(fence))
+                        fence_signal_locked(fence);
+
+                spin_unlock_irqrestore(fence->lock, flags);
+        }
+}
+EXPORT_SYMBOL(fence_enable_sw_signaling);
+
+/**
+ * fence_add_callback - add a callback to be called when the fence
+ * is signaled
+ * @fence:      [in]    the fence to wait on
+ * @cb:         [in]    the callback to register
+ * @func:       [in]    the function to call
+ *
+ * cb will be initialized by fence_add_callback, no initialization
+ * by the caller is required. Any number of callbacks can be registered
+ * to a fence, but a callback can only be registered to one fence at a time.
+ *
+ * Note that the callback can be called from an atomic context.  If
+ * fence is already signaled, this function will return -ENOENT (and
+ * *not* call the callback)
+ *
+ * Add a software callback to the fence. Same restrictions apply to
+ * refcount as it does to fence_wait, however the caller doesn't need to
+ * keep a refcount to fence afterwards: when software access is enabled,
+ * the creator of the fence is required to keep the fence alive until
+ * after it signals with fence_signal. The callback itself can be called
+ * from irq context.
+ *
+ */
+int fence_add_callback(struct fence *fence, struct fence_cb *cb,
+                       fence_func_t func)
+{
+        unsigned long flags;
+        int ret = 0;
+        bool was_set;
+
+        if (WARN_ON(!fence || !func))
+                return -EINVAL;
+
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+                INIT_LIST_HEAD(&cb->node);
+                return -ENOENT;
+        }
+
+        spin_lock_irqsave(fence->lock, flags);
+
+        was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
+
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                ret = -ENOENT;
+        else if (!was_set) {
+                trace_fence_enable_signal(fence);
+
+                if (!fence->ops->enable_signaling(fence)) {
+                        fence_signal_locked(fence);
+                        ret = -ENOENT;
+                }
+        }
+
+        if (!ret) {
+                cb->func = func;
+                list_add_tail(&cb->node, &fence->cb_list);
+        } else
+                INIT_LIST_HEAD(&cb->node);
+        spin_unlock_irqrestore(fence->lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL(fence_add_callback);
+
+/**
+ * fence_remove_callback - remove a callback from the signaling list
+ * @fence:      [in]    the fence to wait on
+ * @cb:         [in]    the callback to remove
+ *
+ * Remove a previously queued callback from the fence. This function returns
+ * true if the callback is succesfully removed, or false if the fence has
+ * already been signaled.
+ *
+ * *WARNING*:
+ * Cancelling a callback should only be done if you really know what you're
+ * doing, since deadlocks and race conditions could occur all too easily. For
+ * this reason, it should only ever be done on hardware lockup recovery,
+ * with a reference held to the fence.
+ */
+bool
+fence_remove_callback(struct fence *fence, struct fence_cb *cb)
+{
+        unsigned long flags;
+        bool ret;
+
+        spin_lock_irqsave(fence->lock, flags);
+
+        ret = !list_empty(&cb->node);
+        if (ret)
+                list_del_init(&cb->node);
+
+        spin_unlock_irqrestore(fence->lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL(fence_remove_callback);
+
+struct default_wait_cb {
+        struct fence_cb base;
+        struct task_struct *task;
+};
+
+static void
+fence_default_wait_cb(struct fence *fence, struct fence_cb *cb)
+{
+        struct default_wait_cb *wait =
+                container_of(cb, struct default_wait_cb, base);
+
+        wake_up_state(wait->task, TASK_NORMAL);
+}
+
+/**
+ * fence_default_wait - default sleep until the fence gets signaled
+ * or until timeout elapses
+ * @fence:      [in]    the fence to wait on
+ * @intr:       [in]    if true, do an interruptible wait
+ * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ *
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
+ * remaining timeout in jiffies on success.
+ */
+signed long
+fence_default_wait(struct fence *fence, bool intr, signed long timeout)
+{
+        struct default_wait_cb cb;
+        unsigned long flags;
+        signed long ret = timeout;
+        bool was_set;
+
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                return timeout;
+
+        spin_lock_irqsave(fence->lock, flags);
+
+        if (intr && signal_pending(current)) {
+                ret = -ERESTARTSYS;
+                goto out;
+        }
+
+        was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
+
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                goto out;
+
+        if (!was_set) {
+                trace_fence_enable_signal(fence);
+
+                if (!fence->ops->enable_signaling(fence)) {
+                        fence_signal_locked(fence);
+                        goto out;
+                }
+        }
+
+        cb.base.func = fence_default_wait_cb;
+        cb.task = current;
+        list_add(&cb.base.node, &fence->cb_list);
+
+        while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
+                if (intr)
+                        __set_current_state(TASK_INTERRUPTIBLE);
+                else
+                        __set_current_state(TASK_UNINTERRUPTIBLE);
+                spin_unlock_irqrestore(fence->lock, flags);
+
+                ret = schedule_timeout(ret);
+
+                spin_lock_irqsave(fence->lock, flags);
+                if (ret > 0 && intr && signal_pending(current))
+                        ret = -ERESTARTSYS;
+        }
+
+        if (!list_empty(&cb.base.node))
+                list_del(&cb.base.node);
+        __set_current_state(TASK_RUNNING);
+
+out:
+        spin_unlock_irqrestore(fence->lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL(fence_default_wait);
+
+/**
+ * fence_init - Initialize a custom fence.
+ * @fence:      [in]    the fence to initialize
+ * @ops:        [in]    the fence_ops for operations on this fence
+ * @lock:       [in]    the irqsafe spinlock to use for locking this fence
+ * @context:    [in]    the execution context this fence is run on
+ * @seqno:      [in]    a linear increasing sequence number for this context
+ *
+ * Initializes an allocated fence, the caller doesn't have to keep its
+ * refcount after committing with this fence, but it will need to hold a
+ * refcount again if fence_ops.enable_signaling gets called. This can
+ * be used for other implementing other types of fence.
+ *
+ * context and seqno are used for easy comparison between fences, allowing
+ * to check which fence is later by simply using fence_later.
+ */
+void
+fence_init(struct fence *fence, const struct fence_ops *ops,
+             spinlock_t *lock, unsigned context, unsigned seqno)
+{
+        BUG_ON(!lock);
+        BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
+               !ops->get_driver_name || !ops->get_timeline_name);
+
+        kref_init(&fence->refcount);
+        fence->ops = ops;
+        INIT_LIST_HEAD(&fence->cb_list);
+        fence->lock = lock;
+        fence->context = context;
+        fence->seqno = seqno;
+        fence->flags = 0UL;
+
+        trace_fence_init(fence);
+}
+EXPORT_SYMBOL(fence_init);
diff --git a/include/linux/fence.h b/include/linux/fence.h
new file mode 100644
index 000000000000..b935cc650123
--- /dev/null
+++ b/include/linux/fence.h
@@ -0,0 +1,343 @@
+/*
+ * Fence mechanism for dma-buf to allow for asynchronous dma access
+ *
+ * Copyright (C) 2012 Canonical Ltd
+ * Copyright (C) 2012 Texas Instruments
+ *
+ * Authors:
+ * Rob Clark <robdclark@gmail.com>
+ * Maarten Lankhorst <maarten.lankhorst@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef __LINUX_FENCE_H
+#define __LINUX_FENCE_H
+
+#include <linux/err.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/bitops.h>
+#include <linux/kref.h>
+#include <linux/sched.h>
+#include <linux/printk.h>
+
+struct fence;
+struct fence_ops;
+struct fence_cb;
+
+/**
+ * struct fence - software synchronization primitive
+ * @refcount: refcount for this fence
+ * @ops: fence_ops associated with this fence
+ * @cb_list: list of all callbacks to call
+ * @lock: spin_lock_irqsave used for locking
+ * @context: execution context this fence belongs to, returned by
+ *           fence_context_alloc()
+ * @seqno: the sequence number of this fence inside the execution context,
+ * can be compared to decide which fence would be signaled later.
+ * @flags: A mask of FENCE_FLAG_* defined below
+ * @timestamp: Timestamp when the fence was signaled.
+ * @status: Optional, only valid if < 0, must be set before calling
+ * fence_signal, indicates that the fence has completed with an error.
+ *
+ * the flags member must be manipulated and read using the appropriate
+ * atomic ops (bit_*), so taking the spinlock will not be needed most
+ * of the time.
+ *
+ * FENCE_FLAG_SIGNALED_BIT - fence is already signaled
+ * FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called*
+ * FENCE_FLAG_USER_BITS - start of the unused bits, can be used by the
+ * implementer of the fence for its own purposes. Can be used in different
+ * ways by different fence implementers, so do not rely on this.
+ *
+ * *) Since atomic bitops are used, this is not guaranteed to be the case.
+ * Particularly, if the bit was set, but fence_signal was called right
+ * before this bit was set, it would have been able to set the
+ * FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called.
+ * Adding a check for FENCE_FLAG_SIGNALED_BIT after setting
+ * FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that
+ * after fence_signal was called, any enable_signaling call will have either
+ * been completed, or never called at all.
+ */
+struct fence {
+        struct kref refcount;
+        const struct fence_ops *ops;
+        struct list_head cb_list;
+        spinlock_t *lock;
+        unsigned context, seqno;
+        unsigned long flags;
+        ktime_t timestamp;
+        int status;
+};
+
+enum fence_flag_bits {
+        FENCE_FLAG_SIGNALED_BIT,
+        FENCE_FLAG_ENABLE_SIGNAL_BIT,
+        FENCE_FLAG_USER_BITS, /* must always be last member */
+};
+
+typedef void (*fence_func_t)(struct fence *fence, struct fence_cb *cb);
+
+/**
+ * struct fence_cb - callback for fence_add_callback
+ * @node: used by fence_add_callback to append this struct to fence::cb_list
+ * @func: fence_func_t to call
+ *
+ * This struct will be initialized by fence_add_callback, additional
+ * data can be passed along by embedding fence_cb in another struct.
+ */
+struct fence_cb {
+        struct list_head node;
+        fence_func_t func;
+};
+
+/**
+ * struct fence_ops - operations implemented for fence
+ * @get_driver_name: returns the driver name.
+ * @get_timeline_name: return the name of the context this fence belongs to.
+ * @enable_signaling: enable software signaling of fence.
+ * @signaled: [optional] peek whether the fence is signaled, can be null.
+ * @wait: custom wait implementation, or fence_default_wait.
+ * @release: [optional] called on destruction of fence, can be null
+ * @fill_driver_data: [optional] callback to fill in free-form debug info
+ * Returns amount of bytes filled, or -errno.
+ * @fence_value_str: [optional] fills in the value of the fence as a string
+ * @timeline_value_str: [optional] fills in the current value of the timeline
+ * as a string
+ *
+ * Notes on enable_signaling:
+ * For fence implementations that have the capability for hw->hw
+ * signaling, they can implement this op to enable the necessary
+ * irqs, or insert commands into cmdstream, etc.  This is called
+ * in the first wait() or add_callback() path to let the fence
+ * implementation know that there is another driver waiting on
+ * the signal (ie. hw->sw case).
+ *
+ * This function can be called called from atomic context, but not
+ * from irq context, so normal spinlocks can be used.
+ *
+ * A return value of false indicates the fence already passed,
+ * or some failure occured that made it impossible to enable
+ * signaling. True indicates succesful enabling.
+ *
+ * fence->status may be set in enable_signaling, but only when false is
+ * returned.
+ *
+ * Calling fence_signal before enable_signaling is called allows
+ * for a tiny race window in which enable_signaling is called during,
+ * before, or after fence_signal. To fight this, it is recommended
+ * that before enable_signaling returns true an extra reference is
+ * taken on the fence, to be released when the fence is signaled.
+ * This will mean fence_signal will still be called twice, but
+ * the second time will be a noop since it was already signaled.
+ *
+ * Notes on signaled:
+ * May set fence->status if returning true.
+ *
+ * Notes on wait:
+ * Must not be NULL, set to fence_default_wait for default implementation.
+ * the fence_default_wait implementation should work for any fence, as long
+ * as enable_signaling works correctly.
+ *
+ * Must return -ERESTARTSYS if the wait is intr = true and the wait was
+ * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
+ * timed out. Can also return other error values on custom implementations,
+ * which should be treated as if the fence is signaled. For example a hardware
+ * lockup could be reported like that.
+ *
+ * Notes on release:
+ * Can be NULL, this function allows additional commands to run on
+ * destruction of the fence. Can be called from irq context.
+ * If pointer is set to NULL, kfree will get called instead.
+ */
+
+struct fence_ops {
+        const char * (*get_driver_name)(struct fence *fence);
+        const char * (*get_timeline_name)(struct fence *fence);
+        bool (*enable_signaling)(struct fence *fence);
+        bool (*signaled)(struct fence *fence);
+        signed long (*wait)(struct fence *fence, bool intr, signed long timeout);
+        void (*release)(struct fence *fence);
+
+        int (*fill_driver_data)(struct fence *fence, void *data, int size);
+        void (*fence_value_str)(struct fence *fence, char *str, int size);
+        void (*timeline_value_str)(struct fence *fence, char *str, int size);
+};
+
+void fence_init(struct fence *fence, const struct fence_ops *ops,
+                spinlock_t *lock, unsigned context, unsigned seqno);
+
+void fence_release(struct kref *kref);
+void fence_free(struct fence *fence);
+
+/**
+ * fence_get - increases refcount of the fence
+ * @fence:      [in]    fence to increase refcount of
+ *
+ * Returns the same fence, with refcount increased by 1.
+ */
+static inline struct fence *fence_get(struct fence *fence)
+{
+        if (fence)
+                kref_get(&fence->refcount);
+        return fence;
+}
+
+/**
+ * fence_put - decreases refcount of the fence
+ * @fence:      [in]    fence to reduce refcount of
+ */
+static inline void fence_put(struct fence *fence)
+{
+        if (fence)
+                kref_put(&fence->refcount, fence_release);
+}
+
+int fence_signal(struct fence *fence);
+int fence_signal_locked(struct fence *fence);
+signed long fence_default_wait(struct fence *fence, bool intr, signed long timeout);
+int fence_add_callback(struct fence *fence, struct fence_cb *cb,
+                       fence_func_t func);
+bool fence_remove_callback(struct fence *fence, struct fence_cb *cb);
+void fence_enable_sw_signaling(struct fence *fence);
+
+/**
+ * fence_is_signaled_locked - Return an indication if the fence is signaled yet.
+ * @fence:      [in]    the fence to check
+ *
+ * Returns true if the fence was already signaled, false if not. Since this
+ * function doesn't enable signaling, it is not guaranteed to ever return
+ * true if fence_add_callback, fence_wait or fence_enable_sw_signaling
+ * haven't been called before.
+ *
+ * This function requires fence->lock to be held.
+ */
+static inline bool
+fence_is_signaled_locked(struct fence *fence)
+{
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                return true;
+
+        if (fence->ops->signaled && fence->ops->signaled(fence)) {
+                fence_signal_locked(fence);
+                return true;
+        }
+
+        return false;
+}
+
+/**
+ * fence_is_signaled - Return an indication if the fence is signaled yet.
+ * @fence:      [in]    the fence to check
+ *
+ * Returns true if the fence was already signaled, false if not. Since this
+ * function doesn't enable signaling, it is not guaranteed to ever return
+ * true if fence_add_callback, fence_wait or fence_enable_sw_signaling
+ * haven't been called before.
+ *
+ * It's recommended for seqno fences to call fence_signal when the
+ * operation is complete, it makes it possible to prevent issues from
+ * wraparound between time of issue and time of use by checking the return
+ * value of this function before calling hardware-specific wait instructions.
+ */
+static inline bool
+fence_is_signaled(struct fence *fence)
+{
+        if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+                return true;
+
+        if (fence->ops->signaled && fence->ops->signaled(fence)) {
+                fence_signal(fence);
+                return true;
+        }
+
+        return false;
+}
+
+/**
+ * fence_later - return the chronologically later fence
+ * @f1: [in]    the first fence from the same context
+ * @f2: [in]    the second fence from the same context
+ *
+ * Returns NULL if both fences are signaled, otherwise the fence that would be
+ * signaled last. Both fences must be from the same context, since a seqno is
+ * not re-used across contexts.
+ */
+static inline struct fence *fence_later(struct fence *f1, struct fence *f2)
+{
+        if (WARN_ON(f1->context != f2->context))
+                return NULL;
+
+        /*
+         * can't check just FENCE_FLAG_SIGNALED_BIT here, it may never have been
+         * set if enable_signaling wasn't called, and enabling that here is
+         * overkill.
+         */
+        if (f2->seqno - f1->seqno <= INT_MAX)
+                return fence_is_signaled(f2) ? NULL : f2;
+        else
+                return fence_is_signaled(f1) ? NULL : f1;
+}
+
+signed long fence_wait_timeout(struct fence *, bool intr, signed long timeout);
+
+
+/**
+ * fence_wait - sleep until the fence gets signaled
+ * @fence:      [in]    the fence to wait on
+ * @intr:       [in]    if true, do an interruptible wait
+ *
+ * This function will return -ERESTARTSYS if interrupted by a signal,
+ * or 0 if the fence was signaled. Other error values may be
+ * returned on custom implementations.
+ *
+ * Performs a synchronous wait on this fence. It is assumed the caller
+ * directly or indirectly holds a reference to the fence, otherwise the
+ * fence might be freed before return, resulting in undefined behavior.
+ */
+static inline signed long fence_wait(struct fence *fence, bool intr)
+{
+        signed long ret;
+
+        /* Since fence_wait_timeout cannot timeout with
+         * MAX_SCHEDULE_TIMEOUT, only valid return values are
+         * -ERESTARTSYS and MAX_SCHEDULE_TIMEOUT.
+         */
+        ret = fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT);
+
+        return ret < 0 ? ret : 0;
+}
+
+unsigned fence_context_alloc(unsigned num);
+
+#define FENCE_TRACE(f, fmt, args...) \
+        do {                                                            \
+                struct fence *__ff = (f);                               \
+                if (config_enabled(CONFIG_FENCE_TRACE))                 \
+                        pr_info("f %u#%u: " fmt,                        \
+                                __ff->context, __ff->seqno, ##args);    \
+        } while (0)
+
+#define FENCE_WARN(f, fmt, args...) \
+        do {                                                            \
+                struct fence *__ff = (f);                               \
+                pr_warn("f %u#%u: " fmt, __ff->context, __ff->seqno,    \
+                         ##args);                                       \
+        } while (0)
+
+#define FENCE_ERR(f, fmt, args...) \
+        do {                                                            \
+                struct fence *__ff = (f);                               \
+                pr_err("f %u#%u: " fmt, __ff->context, __ff->seqno,     \
+                        ##args);                                        \
+        } while (0)
+
+#endif /* __LINUX_FENCE_H */
diff --git a/include/trace/events/fence.h b/include/trace/events/fence.h
new file mode 100644
index 000000000000..98feb1b82896
--- /dev/null
+++ b/include/trace/events/fence.h
@@ -0,0 +1,128 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM fence
+
+#if !defined(_TRACE_FENCE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_FENCE_H
+
+#include <linux/tracepoint.h>
+
+struct fence;
+
+TRACE_EVENT(fence_annotate_wait_on,
+
+        /* fence: the fence waiting on f1, f1: the fence to be waited on. */
+        TP_PROTO(struct fence *fence, struct fence *f1),
+
+        TP_ARGS(fence, f1),
+
+        TP_STRUCT__entry(
+                __string(driver, fence->ops->get_driver_name(fence))
+                __string(timeline, fence->ops->get_driver_name(fence))
+                __field(unsigned int, context)
+                __field(unsigned int, seqno)
+
+                __string(waiting_driver, f1->ops->get_driver_name(f1))
+                __string(waiting_timeline, f1->ops->get_timeline_name(f1))
+                __field(unsigned int, waiting_context)
+                __field(unsigned int, waiting_seqno)
+        ),
+
+        TP_fast_assign(
+                __assign_str(driver, fence->ops->get_driver_name(fence))
+                __assign_str(timeline, fence->ops->get_timeline_name(fence))
+                __entry->context = fence->context;
+                __entry->seqno = fence->seqno;
+
+                __assign_str(waiting_driver, f1->ops->get_driver_name(f1))
+                __assign_str(waiting_timeline, f1->ops->get_timeline_name(f1))
+                __entry->waiting_context = f1->context;
+                __entry->waiting_seqno = f1->seqno;
+
+        ),
+
+        TP_printk("driver=%s timeline=%s context=%u seqno=%u "  \
+                  "waits on driver=%s timeline=%s context=%u seqno=%u",
+                  __get_str(driver), __get_str(timeline), __entry->context,
+                  __entry->seqno,
+                  __get_str(waiting_driver), __get_str(waiting_timeline),
+                  __entry->waiting_context, __entry->waiting_seqno)
+);
+
+DECLARE_EVENT_CLASS(fence,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence),
+
+        TP_STRUCT__entry(
+                __string(driver, fence->ops->get_driver_name(fence))
+                __string(timeline, fence->ops->get_timeline_name(fence))
+                __field(unsigned int, context)
+                __field(unsigned int, seqno)
+        ),
+
+        TP_fast_assign(
+                __assign_str(driver, fence->ops->get_driver_name(fence))
+                __assign_str(timeline, fence->ops->get_timeline_name(fence))
+                __entry->context = fence->context;
+                __entry->seqno = fence->seqno;
+        ),
+
+        TP_printk("driver=%s timeline=%s context=%u seqno=%u",
+                  __get_str(driver), __get_str(timeline), __entry->context,
+                  __entry->seqno)
+);
+
+DEFINE_EVENT(fence, fence_emit,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_init,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_destroy,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_enable_signal,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_signaled,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_wait_start,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+DEFINE_EVENT(fence, fence_wait_end,
+
+        TP_PROTO(struct fence *fence),
+
+        TP_ARGS(fence)
+);
+
+#endif /*  _TRACE_FENCE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>