From 75eefd82581f32da77d7017d11a932ee12a998eb Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 2 Sep 2021 16:20:47 +0200 Subject: [PATCH] drm/i915: Release i915_gem_context from a worker MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The only reason for this really is the i915_gem_engines->fence callback engines_notify(), which exists purely as a fairly funky reference counting scheme for that. Otherwise all other callers are from process context, and generally fairly benign locking context. Unfortunately untangling that requires some major surgery, and we have a few i915_gem_context reference counting bugs that need fixing, and they blow in the current hardirq calling context, so we need a stop-gap measure. Put a FIXME comment in when this should be removable again. v2: Fix mock_context(), noticed by intel-gfx-ci. Acked-by: Acked-by: Maarten Lankhorst Signed-off-by: Daniel Vetter Cc: Jon Bloomfield Cc: Chris Wilson Cc: Maarten Lankhorst Cc: Joonas Lahtinen Cc: Daniel Vetter Cc: "Thomas Hellström" Cc: Matthew Auld Cc: Lionel Landwerlin Cc: Dave Airlie Cc: Jason Ekstrand Link: https://patchwork.freedesktop.org/patch/msgid/20210902142057.929669-1-daniel.vetter@ffwll.ch --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 13 +++++++++++-- drivers/gpu/drm/i915/gem/i915_gem_context_types.h | 12 ++++++++++++ drivers/gpu/drm/i915/gem/selftests/mock_context.c | 1 + 3 files changed, 24 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index fd169cf..051bc35 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -986,9 +986,10 @@ free_engines: return err; } -void i915_gem_context_release(struct kref *ref) +static void i915_gem_context_release_work(struct work_struct *work) { - struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref); + struct i915_gem_context *ctx = container_of(work, typeof(*ctx), + release_work); trace_i915_context_free(ctx); GEM_BUG_ON(!i915_gem_context_is_closed(ctx)); @@ -1002,6 +1003,13 @@ void i915_gem_context_release(struct kref *ref) kfree_rcu(ctx, rcu); } +void i915_gem_context_release(struct kref *ref) +{ + struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref); + + queue_work(ctx->i915->wq, &ctx->release_work); +} + static inline struct i915_gem_engines * __context_engines_static(const struct i915_gem_context *ctx) { @@ -1303,6 +1311,7 @@ i915_gem_create_context(struct drm_i915_private *i915, ctx->sched = pc->sched; mutex_init(&ctx->mutex); INIT_LIST_HEAD(&ctx->link); + INIT_WORK(&ctx->release_work, i915_gem_context_release_work); spin_lock_init(&ctx->stale.lock); INIT_LIST_HEAD(&ctx->stale.engines); 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 94c03a9..0c38789 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h @@ -289,6 +289,18 @@ struct i915_gem_context { struct kref ref; /** + * @release_work: + * + * Work item for deferred cleanup, since i915_gem_context_put() tends to + * be called from hardirq context. + * + * FIXME: The only real reason for this is &i915_gem_engines.fence, all + * other callers are from process context and need at most some mild + * shuffling to pull the i915_gem_context_put() call out of a spinlock. + */ + struct work_struct release_work; + + /** * @rcu: rcu_head for deferred freeing. */ struct rcu_head rcu; diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c index fee070d..067d68a 100644 --- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c +++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c @@ -23,6 +23,7 @@ mock_context(struct drm_i915_private *i915, kref_init(&ctx->ref); INIT_LIST_HEAD(&ctx->link); ctx->i915 = i915; + INIT_WORK(&ctx->release_work, i915_gem_context_release_work); mutex_init(&ctx->mutex); -- 2.7.4