On 02/09/2021 21:02, Daniel Vetter wrote:
On Thu, Sep 2, 2021 at 6:20 PM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 02/09/2021 16:05, Daniel Vetter wrote:
On Thu, Sep 2, 2021 at 2:42 PM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 13/08/2021 21:30, Daniel Vetter wrote:
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.
There is reset which definitely isn't process context.
gpu reset runs in process context. The tasklet context is the engines_notify I'm talking about above.
I haven't looked very deeply but please double check the path from execlists_submission_tasklet -> execlists_reset -> intel_engine_reset -> __intel_engine_reset -> execlists_reset_rewind -> execlists_reset_csb -> execlists_reset_active -> __i915_request_reset -> mark_guilty -> i915_gem_context_put.
Thanks for pointing this out, I'll add it to the commit message.
More stuff to fix, yay.
Otherwise I did not really get from the commit message is this patch fixing an existing problem or preparing something for the future. If the former then as I wrote above - I am pretty sure there are call sites from the tasklet already.
Regards,
Tvrtko
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.
I guess this para wasn't clear, but subsequent patches fix the refcount bugs and need this prep patch here.
So up to where in the series are those fixes and where other stuff follows? Worth spliting and having cover letters perhaps? Is the fixing part applicable to the existing code or only comes to play with the syncobj single timeline changes?
There's Fixes: lines. One is timeline syncobj, the other is 2 years old.
So first two patches are standalone and fix the immediate bug? Could you describe the composition and doings of the series in a cover letter so it's possible to have an overview of chunk of work tackled?
Regards,
Tvrtko
-Daniel
Regards,
Tvrtko
-Daniel
Put a FIXME comment in when this should be removable again.
Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Jon Bloomfield jon.bloomfield@intel.com Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: "Thomas Hellström" thomas.hellstrom@linux.intel.com Cc: Matthew Auld matthew.auld@intel.com Cc: Lionel Landwerlin lionel.g.landwerlin@intel.com Cc: Dave Airlie airlied@redhat.com Cc: Jason Ekstrand jason@jlekstrand.net
drivers/gpu/drm/i915/gem/i915_gem_context.c | 13 +++++++++++-- drivers/gpu/drm/i915/gem/i915_gem_context_types.h | 12 ++++++++++++ 2 files changed, 23 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 fd169cf2f75a..051bc357ff65 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 @@ static struct i915_gem_engines *user_engines(struct i915_gem_context *ctx, 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 94c03a97cb77..0c38789bd4a8 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h @@ -288,6 +288,18 @@ 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. */