On 27/02/2020 11:01, Chris Wilson wrote:
Use the same engine_idle_release() routine for cleaning all old
ctx->engine[] state, closing any potential races with concurrent execbuf
submission.
v2ish: Use the ce->pin_count to close the execbuf gap.
Closes: https://gitlab.freedesktop.org/drm/intel/issues/1241
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
Remember to initialise the mock_context as well.
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 193 +++++++++---------
drivers/gpu/drm/i915/gem/i915_gem_context.h | 1 -
.../gpu/drm/i915/gem/selftests/mock_context.c | 3 +
3 files changed, 105 insertions(+), 92 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index e525ead073f7..cb6b6be48978 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -242,7 +242,6 @@ static void __free_engines(struct i915_gem_engines *e, unsigned int count)
if (!e->engines[count])
continue;
- RCU_INIT_POINTER(e->engines[count]->gem_context, NULL);
intel_context_put(e->engines[count]);
}
kfree(e);
@@ -255,7 +254,11 @@ static void free_engines(struct i915_gem_engines *e)
static void free_engines_rcu(struct rcu_head *rcu)
{
- free_engines(container_of(rcu, struct i915_gem_engines, rcu));
+ struct i915_gem_engines *engines =
+ container_of(rcu, struct i915_gem_engines, rcu);
+
+ i915_sw_fence_fini(&engines->fence);
+ free_engines(engines);
}
static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
@@ -269,8 +272,6 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
if (!e)
return ERR_PTR(-ENOMEM);
- e->ctx = ctx;
-
for_each_engine(engine, gt, id) {
struct intel_context *ce;
@@ -304,7 +305,6 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
list_del(&ctx->link);
spin_unlock(&ctx->i915->gem.contexts.lock);
- free_engines(rcu_access_pointer(ctx->engines));
mutex_destroy(&ctx->engines_mutex);
if (ctx->timeline)
@@ -491,30 +491,104 @@ static void kill_engines(struct i915_gem_engines *engines)
static void kill_stale_engines(struct i915_gem_context *ctx)
{
struct i915_gem_engines *pos, *next;
- unsigned long flags;
- spin_lock_irqsave(&ctx->stale.lock, flags);
+ spin_lock_irq(&ctx->stale.lock);
+ GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
list_for_each_entry_safe(pos, next, &ctx->stale.engines, link) {
- if (!i915_sw_fence_await(&pos->fence))
+ if (!i915_sw_fence_await(&pos->fence)) {
+ list_del_init(&pos->link);
continue;
+ }
- spin_unlock_irqrestore(&ctx->stale.lock, flags);
+ spin_unlock_irq(&ctx->stale.lock);
kill_engines(pos);
- spin_lock_irqsave(&ctx->stale.lock, flags);
+ spin_lock_irq(&ctx->stale.lock);
+ GEM_BUG_ON(i915_sw_fence_signaled(&pos->fence));
list_safe_reset_next(pos, next, link);
list_del_init(&pos->link); /* decouple from FENCE_COMPLETE */
i915_sw_fence_complete(&pos->fence);
}
- spin_unlock_irqrestore(&ctx->stale.lock, flags);
+ spin_unlock_irq(&ctx->stale.lock);
}
static void kill_context(struct i915_gem_context *ctx)
{
kill_stale_engines(ctx);
- kill_engines(__context_engines_static(ctx));
+}
+
+static int engines_notify(struct i915_sw_fence *fence,
+ enum i915_sw_fence_notify state)
+{
+ struct i915_gem_engines *engines =
+ container_of(fence, typeof(*engines), fence);
+
+ switch (state) {
+ case FENCE_COMPLETE:
+ if (!list_empty(&engines->link)) {
+ struct i915_gem_context *ctx = engines->ctx;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->stale.lock, flags);
+ list_del(&engines->link);
+ spin_unlock_irqrestore(&ctx->stale.lock, flags);
+ }
+ i915_gem_context_put(engines->ctx);
+ break;
+
+ case FENCE_FREE:
+ init_rcu_head(&engines->rcu);
+ call_rcu(&engines->rcu, free_engines_rcu);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static void engines_idle_release(struct i915_gem_context *ctx,
+ struct i915_gem_engines *engines)
+{
+ struct i915_gem_engines_iter it;
+ struct intel_context *ce;
+
+ i915_sw_fence_init(&engines->fence, engines_notify);
+ INIT_LIST_HEAD(&engines->link);
+
+ engines->ctx = i915_gem_context_get(ctx);
+
+ for_each_gem_engine(ce, engines, it) {
+ struct dma_fence *fence;
+ int err = 0;
+
+ /* serialises with execbuf */
+ RCU_INIT_POINTER(ce->gem_context, NULL);
What is the purpose of this? Looks dodgy - like it can't really
guarantee much.
+ if (!intel_context_pin_if_active(ce))
+ continue;
+
+ fence = i915_active_fence_get(&ce->timeline->last_request);
+ if (fence) {
+ err = i915_sw_fence_await_dma_fence(&engines->fence,
+ fence, 0,
+ GFP_KERNEL);
+ dma_fence_put(fence);
+ }
+ intel_context_unpin(ce);
+ if (err < 0)
+ goto kill;
+ }
+
+ spin_lock_irq(&ctx->stale.lock);
+ if (!i915_gem_context_is_closed(ctx))
+ list_add_tail(&engines->link, &ctx->stale.engines);
+ spin_unlock_irq(&ctx->stale.lock);
+
+kill:
+ if (list_empty(&engines->link)) /* raced, already closed */
+ kill_engines(engines);
Raced with.. ? context_close? Can't be the fence yet, before it has been
committed.
Regards,
Tvrtko
+
+ i915_sw_fence_commit(&engines->fence);
}
static void set_closed_name(struct i915_gem_context *ctx)
@@ -538,11 +612,16 @@ static void context_close(struct i915_gem_context *ctx)
{
struct i915_address_space *vm;
+ /* Flush any concurrent set_engines() */
+ mutex_lock(&ctx->engines_mutex);
+ engines_idle_release(ctx, rcu_replace_pointer(ctx->engines, NULL, 1));
i915_gem_context_set_closed(ctx);
- set_closed_name(ctx);
+ mutex_unlock(&ctx->engines_mutex);
mutex_lock(&ctx->mutex);
+ set_closed_name(ctx);
+
vm = i915_gem_context_vm(ctx);
if (vm)
i915_vm_close(vm);
@@ -1626,77 +1705,6 @@ static const i915_user_extension_fn set_engines__extensions[] = {
[I915_CONTEXT_ENGINES_EXT_BOND] = set_engines__bond,
};
-static int engines_notify(struct i915_sw_fence *fence,
- enum i915_sw_fence_notify state)
-{
- struct i915_gem_engines *engines =
- container_of(fence, typeof(*engines), fence);
-
- switch (state) {
- case FENCE_COMPLETE:
- if (!list_empty(&engines->link)) {
- struct i915_gem_context *ctx = engines->ctx;
- unsigned long flags;
-
- spin_lock_irqsave(&ctx->stale.lock, flags);
- list_del(&engines->link);
- spin_unlock_irqrestore(&ctx->stale.lock, flags);
- }
- break;
-
- case FENCE_FREE:
- init_rcu_head(&engines->rcu);
- call_rcu(&engines->rcu, free_engines_rcu);
- break;
- }
-
- return NOTIFY_DONE;
-}
-
-static void engines_idle_release(struct i915_gem_engines *engines)
-{
- struct i915_gem_engines_iter it;
- struct intel_context *ce;
- unsigned long flags;
-
- GEM_BUG_ON(!engines);
- i915_sw_fence_init(&engines->fence, engines_notify);
-
- INIT_LIST_HEAD(&engines->link);
- spin_lock_irqsave(&engines->ctx->stale.lock, flags);
- if (!i915_gem_context_is_closed(engines->ctx))
- list_add(&engines->link, &engines->ctx->stale.engines);
- spin_unlock_irqrestore(&engines->ctx->stale.lock, flags);
- if (list_empty(&engines->link)) /* raced, already closed */
- goto kill;
-
- for_each_gem_engine(ce, engines, it) {
- struct dma_fence *fence;
- int err;
-
- if (!ce->timeline)
- continue;
-
- fence = i915_active_fence_get(&ce->timeline->last_request);
- if (!fence)
- continue;
-
- err = i915_sw_fence_await_dma_fence(&engines->fence,
- fence, 0,
- GFP_KERNEL);
-
- dma_fence_put(fence);
- if (err < 0)
- goto kill;
- }
- goto out;
-
-kill:
- kill_engines(engines);
-out:
- i915_sw_fence_commit(&engines->fence);
-}
-
static int
set_engines(struct i915_gem_context *ctx,
const struct drm_i915_gem_context_param *args)
@@ -1739,8 +1747,6 @@ set_engines(struct i915_gem_context *ctx,
if (!set.engines)
return -ENOMEM;
- set.engines->ctx = ctx;
-
for (n = 0; n < num_engines; n++) {
struct i915_engine_class_instance ci;
struct intel_engine_cs *engine;
@@ -1793,6 +1799,11 @@ set_engines(struct i915_gem_context *ctx,
replace:
mutex_lock(&ctx->engines_mutex);
+ if (i915_gem_context_is_closed(ctx)) {
+ mutex_unlock(&ctx->engines_mutex);
+ free_engines(set.engines);
+ return -ENOENT;
+ }
if (args->size)
i915_gem_context_set_user_engines(ctx);
else
@@ -1801,7 +1812,7 @@ set_engines(struct i915_gem_context *ctx,
mutex_unlock(&ctx->engines_mutex);
/* Keep track of old engine sets for kill_context() */
- engines_idle_release(set.engines);
+ engines_idle_release(ctx, set.engines);
return 0;
}
@@ -2077,8 +2088,6 @@ static int clone_engines(struct i915_gem_context *dst,
if (!clone)
goto err_unlock;
- clone->ctx = dst;
-
for (n = 0; n < e->num_engines; n++) {
struct intel_engine_cs *engine;
@@ -2121,8 +2130,7 @@ static int clone_engines(struct i915_gem_context *dst,
i915_gem_context_unlock_engines(src);
/* Serialised by constructor */
- free_engines(__context_engines_static(dst));
- RCU_INIT_POINTER(dst->engines, clone);
+ engines_idle_release(dst, rcu_replace_pointer(dst->engines, clone, 1));
if (user_engines)
i915_gem_context_set_user_engines(dst);
else
@@ -2553,6 +2561,9 @@ i915_gem_engines_iter_next(struct i915_gem_engines_iter *it)
const struct i915_gem_engines *e = it->engines;
struct intel_context *ctx;
+ if (unlikely(!e))
+ return NULL;
+
do {
if (it->idx >= e->num_engines)
return NULL;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h b/drivers/gpu/drm/i915/gem/i915_gem_context.h
index 3ae61a355d87..57b7ae2893e1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h
@@ -207,7 +207,6 @@ static inline void
i915_gem_engines_iter_init(struct i915_gem_engines_iter *it,
struct i915_gem_engines *engines)
{
- GEM_BUG_ON(!engines);
it->engines = engines;
it->idx = 0;
}
diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
index b12ea1daa29d..e7e3c620f542 100644
--- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
@@ -23,6 +23,9 @@ mock_context(struct drm_i915_private *i915,
INIT_LIST_HEAD(&ctx->link);
ctx->i915 = i915;
+ spin_lock_init(&ctx->stale.lock);
+ INIT_LIST_HEAD(&ctx->stale.engines);
+
i915_gem_context_set_persistence(ctx);
mutex_init(&ctx->engines_mutex);
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