Now that we have fence tracking in place for object allocations, we can
remove the haphazard polling over a workqueue used for asynchronous
userptr allocations. All consumers will now wait for the fence
notification instead of leaking EAGAIN back to userspace.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |   5 -
 .../gpu/drm/i915/gem/i915_gem_object_types.h  |   1 -
 drivers/gpu/drm/i915/gem/i915_gem_pages.c     |   6 +-
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c   | 136 ++++++++----------
 drivers/gpu/drm/i915/i915_drv.h               |   9 +-
 drivers/gpu/drm/i915/i915_gem.c               |   4 +-
 6 files changed, 66 insertions(+), 95 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 59750edd617f..60926209b1fc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1456,11 +1456,6 @@ static int eb_reserve(struct i915_execbuffer *eb)
                if (signal_pending(current))
                        return -EINTR;
 
-               if (err == -EAGAIN) {
-                       flush_workqueue(eb->i915->mm.userptr_wq);
-                       continue;
-               }
-
                /* Now safe to wait with no reservations held */
                list_for_each_entry(ev, &eb->unbound, bind_link) {
                        struct i915_vma *vma = ev->vma;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h 
b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 668b249fd109..17a47186ba81 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -278,7 +278,6 @@ struct drm_i915_gem_object {
 
                        struct i915_mm_struct *mm;
                        struct i915_mmu_object *mmu_object;
-                       struct work_struct *work;
                } userptr;
 
                unsigned long scratch;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c 
b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 4efd1aeedc2d..99f50c9d0ed6 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -18,8 +18,6 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object 
*obj,
        unsigned long supported = INTEL_INFO(i915)->page_sizes;
        int i;
 
-       assert_object_held(obj);
-
        if (i915_gem_object_is_volatile(obj))
                obj->mm.madv = I915_MADV_DONTNEED;
 
@@ -34,8 +32,6 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object 
*obj,
        obj->mm.get_page.sg_pos = pages->sgl;
        obj->mm.get_page.sg_idx = 0;
 
-       obj->mm.pages = pages;
-
        if (i915_gem_object_is_tiled(obj) &&
            i915->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
                GEM_BUG_ON(obj->mm.quirked);
@@ -61,6 +57,8 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object 
*obj,
        }
        GEM_BUG_ON(!HAS_PAGE_SIZES(i915, obj->mm.page_sizes.sg));
 
+       WRITE_ONCE(obj->mm.pages, pages);
+
        if (i915_gem_object_is_shrinkable(obj)) {
                struct list_head *list;
                unsigned long flags;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c 
b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 4cd79f425eac..a236df02bc44 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -14,6 +14,7 @@
 #include "i915_gem_ioctls.h"
 #include "i915_gem_object.h"
 #include "i915_scatterlist.h"
+#include "i915_sw_fence_work.h"
 
 struct i915_mm_struct {
        struct mm_struct *mm;
@@ -398,7 +399,7 @@ i915_gem_userptr_release__mm_struct(struct 
drm_i915_gem_object *obj)
 }
 
 struct get_pages_work {
-       struct work_struct work;
+       struct dma_fence_work base;
        struct drm_i915_gem_object *obj;
        struct task_struct *task;
 };
@@ -446,12 +447,12 @@ __i915_gem_userptr_alloc_pages(struct drm_i915_gem_object 
*obj,
        return st;
 }
 
-static void
-__i915_gem_userptr_get_pages_worker(struct work_struct *_work)
+static int gup_work(struct dma_fence_work *base)
 {
-       struct get_pages_work *work = container_of(_work, typeof(*work), work);
-       struct drm_i915_gem_object *obj = work->obj;
+       struct get_pages_work *gup = container_of(base, typeof(*gup), base);
+       struct drm_i915_gem_object *obj = gup->obj;
        const unsigned long npages = obj->base.size >> PAGE_SHIFT;
+       struct sg_table *pages;
        unsigned long pinned;
        struct page **pvec;
        int ret;
@@ -476,7 +477,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct 
*_work)
                                        locked = 1;
                                }
                                ret = pin_user_pages_remote
-                                       (work->task, mm,
+                                       (gup->task, mm,
                                         obj->userptr.ptr + pinned * PAGE_SIZE,
                                         npages - pinned,
                                         flags,
@@ -492,37 +493,41 @@ __i915_gem_userptr_get_pages_worker(struct work_struct 
*_work)
                }
        }
 
-       i915_gem_object_lock(obj);
-       if (obj->userptr.work == &work->work) {
-               struct sg_table *pages = ERR_PTR(ret);
-
-               if (pinned == npages) {
-                       pages = __i915_gem_userptr_alloc_pages(obj, pvec,
-                                                              npages);
-                       if (!IS_ERR(pages)) {
-                               pinned = 0;
-                               pages = NULL;
-                       }
+       if (pinned == npages) {
+               pages = __i915_gem_userptr_alloc_pages(obj, pvec, npages);
+               if (!IS_ERR(pages)) {
+                       pinned = 0;
+                       pages = NULL;
                }
-
-               obj->userptr.work = ERR_CAST(pages);
-               if (IS_ERR(pages))
-                       __i915_gem_userptr_set_active(obj, false);
+       } else {
+               pages = ERR_PTR(ret);
        }
-       i915_gem_object_unlock(obj);
+       if (IS_ERR(pages))
+               __i915_gem_userptr_set_active(obj, false);
 
        unpin_user_pages(pvec, pinned);
        kvfree(pvec);
 
-       i915_gem_object_put(obj);
-       put_task_struct(work->task);
-       kfree(work);
+       return PTR_ERR_OR_ZERO(pages);
 }
 
-static struct sg_table *
+static void gup_release(struct dma_fence_work *base)
+{
+       struct get_pages_work *gup = container_of(base, typeof(*gup), base);
+
+       put_task_struct(gup->task);
+}
+
+static const struct dma_fence_work_ops gup_ops = {
+       .name = "userptr-getpages",
+       .work = gup_work,
+       .release = gup_release,
+};
+
+static bool
 __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj)
 {
-       struct get_pages_work *work;
+       struct get_pages_work *gup;
 
        /* Spawn a worker so that we can acquire the
         * user pages without holding our mutex. Access
@@ -543,21 +548,21 @@ __i915_gem_userptr_get_pages_schedule(struct 
drm_i915_gem_object *obj)
         * that error back to this function through
         * obj->userptr.work = ERR_PTR.
         */
-       work = kmalloc(sizeof(*work), GFP_KERNEL);
-       if (work == NULL)
-               return ERR_PTR(-ENOMEM);
-
-       obj->userptr.work = &work->work;
+       gup = kmalloc(sizeof(*gup), GFP_KERNEL);
+       if (!gup)
+               return false;
 
-       work->obj = i915_gem_object_get(obj);
+       dma_fence_work_init(&gup->base, &gup_ops);
 
-       work->task = current;
-       get_task_struct(work->task);
+       gup->obj = obj;
+       i915_active_set_exclusive(&obj->mm.active, &gup->base.dma);
 
-       INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker);
-       queue_work(to_i915(obj->base.dev)->mm.userptr_wq, &work->work);
+       gup->task = current;
+       get_task_struct(gup->task);
 
-       return ERR_PTR(-EAGAIN);
+       dma_resv_add_excl_fence(obj->base.resv, &gup->base.dma);
+       dma_fence_work_commit(&gup->base);
+       return true;
 }
 
 static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
@@ -566,7 +571,6 @@ static int i915_gem_userptr_get_pages(struct 
drm_i915_gem_object *obj)
        struct mm_struct *mm = obj->userptr.mm->mm;
        struct page **pvec;
        struct sg_table *pages;
-       bool active;
        int pinned;
        unsigned int gup_flags = 0;
 
@@ -587,14 +591,6 @@ static int i915_gem_userptr_get_pages(struct 
drm_i915_gem_object *obj)
         * egregious cases from causing harm.
         */
 
-       if (obj->userptr.work) {
-               /* active flag should still be held for the pending work */
-               if (IS_ERR(obj->userptr.work))
-                       return PTR_ERR(obj->userptr.work);
-               else
-                       return -EAGAIN;
-       }
-
        pvec = NULL;
        pinned = 0;
 
@@ -618,28 +614,31 @@ static int i915_gem_userptr_get_pages(struct 
drm_i915_gem_object *obj)
                        pinned = pin_user_pages_fast_only(obj->userptr.ptr,
                                                          num_pages, gup_flags,
                                                          pvec);
+                       if (pinned < 0)
+                               goto out;
                }
        }
 
-       active = false;
-       if (pinned < 0) {
-               pages = ERR_PTR(pinned);
-               pinned = 0;
-       } else if (pinned < num_pages) {
-               pages = __i915_gem_userptr_get_pages_schedule(obj);
-               active = pages == ERR_PTR(-EAGAIN);
-       } else {
+       if (pinned == num_pages) {
                pages = __i915_gem_userptr_alloc_pages(obj, pvec, num_pages);
-               active = !IS_ERR(pages);
+               if (IS_ERR(pages)) {
+                       unpin_user_pages(pvec, pinned);
+                       pinned = PTR_ERR(pages);
+                       goto out;
+               }
+       } else {
+               unpin_user_pages(pvec, pinned);
+               if (!__i915_gem_userptr_get_pages_schedule(obj)) {
+                       pinned = -ENOMEM;
+                       goto out;
+               }
        }
-       if (active)
-               __i915_gem_userptr_set_active(obj, true);
+       __i915_gem_userptr_set_active(obj, true);
+       pinned = 0;
 
-       if (IS_ERR(pages))
-               unpin_user_pages(pvec, pinned);
+out:
        kvfree(pvec);
-
-       return PTR_ERR_OR_ZERO(pages);
+       return pinned;
 }
 
 static void
@@ -650,7 +649,6 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
        struct page *page;
 
        /* Cancel any inflight work and force them to restart their gup */
-       obj->userptr.work = NULL;
        __i915_gem_userptr_set_active(obj, false);
        if (!pages)
                return;
@@ -853,22 +851,12 @@ i915_gem_userptr_ioctl(struct drm_device *dev,
        return 0;
 }
 
-int i915_gem_init_userptr(struct drm_i915_private *dev_priv)
+void i915_gem_init_userptr(struct drm_i915_private *dev_priv)
 {
        spin_lock_init(&dev_priv->mm_lock);
        hash_init(dev_priv->mm_structs);
-
-       dev_priv->mm.userptr_wq =
-               alloc_workqueue("i915-userptr-acquire",
-                               WQ_HIGHPRI | WQ_UNBOUND,
-                               0);
-       if (!dev_priv->mm.userptr_wq)
-               return -ENOMEM;
-
-       return 0;
 }
 
 void i915_gem_cleanup_userptr(struct drm_i915_private *dev_priv)
 {
-       destroy_workqueue(dev_priv->mm.userptr_wq);
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 072b1e19d86a..85c11912288a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -604,13 +604,6 @@ struct i915_gem_mm {
        struct notifier_block vmap_notifier;
        struct shrinker shrinker;
 
-       /**
-        * Workqueue to fault in userptr pages, flushed by the execbuf
-        * when required but otherwise left to userspace to try again
-        * on EAGAIN.
-        */
-       struct workqueue_struct *userptr_wq;
-
        /* shrinker accounting, also useful for userland debugging */
        u64 shrink_memory;
        u32 shrink_count;
@@ -1724,7 +1717,7 @@ int i915_getparam_ioctl(struct drm_device *dev, void 
*data,
                        struct drm_file *file_priv);
 
 /* i915_gem.c */
-int i915_gem_init_userptr(struct drm_i915_private *dev_priv);
+void i915_gem_init_userptr(struct drm_i915_private *dev_priv);
 void i915_gem_cleanup_userptr(struct drm_i915_private *dev_priv);
 void i915_gem_init_early(struct drm_i915_private *dev_priv);
 void i915_gem_cleanup_early(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0fbe438c4523..f886a98dc2ae 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1133,9 +1133,7 @@ int i915_gem_init(struct drm_i915_private *dev_priv)
                mkwrite_device_info(dev_priv)->page_sizes =
                        I915_GTT_PAGE_SIZE_4K;
 
-       ret = i915_gem_init_userptr(dev_priv);
-       if (ret)
-               return ret;
+       i915_gem_init_userptr(dev_priv);
 
        intel_uc_fetch_firmwares(&dev_priv->gt.uc);
        intel_wopcm_init(&dev_priv->wopcm);
-- 
2.20.1

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