From f7ce8639f6ff7f9445cb18114282371a41ceb840 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 3 Jul 2020 01:43:06 +0100 Subject: [PATCH] drm/i915/gem: Split the context's obj:vma lut into its own mutex 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 Reviewed-by: Andi Shyti Link: https://patchwork.freedesktop.org/patch/msgid/20200703004306.11117-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 11 +++++++---- drivers/gpu/drm/i915/gem/i915_gem_context_types.h | 1 + drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 19 +++++++++++++------ drivers/gpu/drm/i915/gem/i915_gem_object.c | 4 ++-- drivers/gpu/drm/i915/gem/selftests/mock_context.c | 4 +++- 5 files changed, 26 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 6675447..41784df 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 28760bd..ae14ca2 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 b4862af..dd15a79 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -782,10 +782,15 @@ 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)) { + struct i915_address_space *vm = rcu_access_pointer(ctx->vm); + + if (unlikely(vm && vma->vm != 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 +803,7 @@ 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 +819,8 @@ err: 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 +828,7 @@ 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 +838,7 @@ 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 eb35bdd1..c8421fd 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 aa0d06c..51b5a34 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; -- 2.7.4