[PATCH 01/20] drm/i915/gem: Split the context's obj:vma lut into its own mutex
Chris Wilson
chris at chris-wilson.co.uk
Fri Jul 3 00:43:05 UTC 2020
Rather than reuse the common ctx->mutex for locking the execbuffer LUT,
split it into its own lock to avoid being taken [as part of ctx->mutex]
at inappropriate times. In particular to avoid the inversion from taking
the timeline->mutex for the whole execbuf submission in the next patch.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti at intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 11 +++++++----
.../gpu/drm/i915/gem/i915_gem_context_types.h | 1 +
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 17 +++++++++++------
drivers/gpu/drm/i915/gem/i915_gem_object.c | 4 ++--
.../gpu/drm/i915/gem/selftests/mock_context.c | 4 +++-
5 files changed, 24 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 6675447a47b9..41784df51e58 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -101,8 +101,7 @@ static void lut_close(struct i915_gem_context *ctx)
struct radix_tree_iter iter;
void __rcu **slot;
- lockdep_assert_held(&ctx->mutex);
-
+ mutex_lock(&ctx->lut_mutex);
rcu_read_lock();
radix_tree_for_each_slot(slot, &ctx->handles_vma, &iter, 0) {
struct i915_vma *vma = rcu_dereference_raw(*slot);
@@ -135,6 +134,7 @@ static void lut_close(struct i915_gem_context *ctx)
i915_gem_object_put(obj);
}
rcu_read_unlock();
+ mutex_unlock(&ctx->lut_mutex);
}
static struct intel_context *
@@ -342,6 +342,7 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
spin_unlock(&ctx->i915->gem.contexts.lock);
mutex_destroy(&ctx->engines_mutex);
+ mutex_destroy(&ctx->lut_mutex);
if (ctx->timeline)
intel_timeline_put(ctx->timeline);
@@ -725,6 +726,7 @@ __create_context(struct drm_i915_private *i915)
RCU_INIT_POINTER(ctx->engines, e);
INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
+ mutex_init(&ctx->lut_mutex);
/* NB: Mark all slices as needing a remap so that when the context first
* loads it will restore whatever remap state already exists. If there
@@ -1312,11 +1314,11 @@ static int set_ppgtt(struct drm_i915_file_private *file_priv,
if (vm == rcu_access_pointer(ctx->vm))
goto unlock;
+ old = __set_ppgtt(ctx, vm);
+
/* Teardown the existing obj:vma cache, it will have to be rebuilt. */
lut_close(ctx);
- old = __set_ppgtt(ctx, vm);
-
/*
* We need to flush any requests using the current ppgtt before
* we release it as the requests do not hold a reference themselves,
@@ -1330,6 +1332,7 @@ static int set_ppgtt(struct drm_i915_file_private *file_priv,
if (err) {
i915_vm_close(__set_ppgtt(ctx, old));
i915_vm_close(old);
+ lut_close(ctx); /* force a rebuild of the old obj:vma cache */
}
unlock:
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
index 28760bd03265..ae14ca24a11f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
@@ -170,6 +170,7 @@ struct i915_gem_context {
* per vm, which may be one per context or shared with the global GTT)
*/
struct radix_tree_root handles_vma;
+ struct mutex lut_mutex;
/**
* @name: arbitrary name, used for user debug
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index b4862afaaf28..e9bb85b679b4 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -782,10 +782,13 @@ static int __eb_add_lut(struct i915_execbuffer *eb,
/* Check that the context hasn't been closed in the meantime */
err = -EINTR;
- if (!mutex_lock_interruptible(&ctx->mutex)) {
- err = -ENOENT;
- if (likely(!i915_gem_context_is_closed(ctx)))
+ if (!mutex_lock_interruptible(&ctx->lut_mutex)) {
+ if (unlikely(ctx->vm && vma->vm != ctx->vm))
+ err = -EAGAIN; /* user racing with ctx set-vm */
+ else if (likely(!i915_gem_context_is_closed(ctx)))
err = radix_tree_insert(&ctx->handles_vma, handle, vma);
+ else
+ err = -ENOENT;
if (err == 0) { /* And nor has this handle */
struct drm_i915_gem_object *obj = vma->obj;
@@ -798,7 +801,7 @@ static int __eb_add_lut(struct i915_execbuffer *eb,
}
spin_unlock(&obj->lut_lock);
}
- mutex_unlock(&ctx->mutex);
+ mutex_unlock(&ctx->lut_mutex);
}
if (unlikely(err))
goto err;
@@ -814,6 +817,8 @@ static int __eb_add_lut(struct i915_execbuffer *eb,
static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
{
+ struct i915_address_space *vm = eb->context->vm;
+
do {
struct drm_i915_gem_object *obj;
struct i915_vma *vma;
@@ -821,7 +826,7 @@ static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
rcu_read_lock();
vma = radix_tree_lookup(&eb->gem_context->handles_vma, handle);
- if (likely(vma))
+ if (likely(vma && vma->vm == vm))
vma = i915_vma_tryget(vma);
rcu_read_unlock();
if (likely(vma))
@@ -831,7 +836,7 @@ static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
if (unlikely(!obj))
return ERR_PTR(-ENOENT);
- vma = i915_vma_instance(obj, eb->context->vm, NULL);
+ vma = i915_vma_instance(obj, vm, NULL);
if (IS_ERR(vma)) {
i915_gem_object_put(obj);
return vma;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index eb35bdd10c09..c8421fd9d2dc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -143,14 +143,14 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
* vma, in the same fd namespace, by virtue of flink/open.
*/
- mutex_lock(&ctx->mutex);
+ mutex_lock(&ctx->lut_mutex);
vma = radix_tree_delete(&ctx->handles_vma, lut->handle);
if (vma) {
GEM_BUG_ON(vma->obj != obj);
GEM_BUG_ON(!atomic_read(&vma->open_count));
i915_vma_close(vma);
}
- mutex_unlock(&ctx->mutex);
+ mutex_unlock(&ctx->lut_mutex);
i915_gem_context_put(lut->ctx);
i915_lut_handle_free(lut);
diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
index aa0d06cf1903..51b5a3421b40 100644
--- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
@@ -23,6 +23,8 @@ mock_context(struct drm_i915_private *i915,
INIT_LIST_HEAD(&ctx->link);
ctx->i915 = i915;
+ mutex_init(&ctx->mutex);
+
spin_lock_init(&ctx->stale.lock);
INIT_LIST_HEAD(&ctx->stale.engines);
@@ -35,7 +37,7 @@ mock_context(struct drm_i915_private *i915,
RCU_INIT_POINTER(ctx->engines, e);
INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
- mutex_init(&ctx->mutex);
+ mutex_init(&ctx->lut_mutex);
if (name) {
struct i915_ppgtt *ppgtt;
--
2.20.1
More information about the Intel-gfx-trybot
mailing list