| Message ID | 20200211144831.1011498-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] drm/i915/gem: Don't leak non-persistent requests on changing engines | expand |
On 11/02/2020 14:48, Chris Wilson wrote: > If we have a set of active engines marked as being non-persistent, we > lose track of those if the user replaces those engines with > I915_CONTEXT_PARAM_ENGINES. As part of our uABI contract is that > non-persistent requests are terminated if they are no longer being > tracked by the user's context (in order to prevent a lost request > causing an untracked and so unstoppable GPU hang), we need to apply the > same context cancellation upon changing engines. > > v2: Track stale engines[] so we only reap at context closure. > v3: Tvrtko spotted races with closing contexts and set-engines, so add a > veneer of kill-everything paranoia to clean up after losing a race. > > Fixes: a0e047156cde ("drm/i915/gem: Make context persistence optional") > Testcase: igt/gem_ctx_peristence/replace > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > --- > drivers/gpu/drm/i915/gem/i915_gem_context.c | 122 ++++++++++++++++-- > .../gpu/drm/i915/gem/i915_gem_context_types.h | 13 +- > drivers/gpu/drm/i915/i915_sw_fence.c | 17 ++- > drivers/gpu/drm/i915/i915_sw_fence.h | 2 +- > 4 files changed, 141 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 cfaf5bbdbcab..3e82739bdbc0 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c > @@ -270,7 +270,8 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx) > if (!e) > return ERR_PTR(-ENOMEM); > > - init_rcu_head(&e->rcu); > + e->ctx = ctx; > + > for_each_engine(engine, gt, id) { > struct intel_context *ce; > > @@ -450,7 +451,7 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce) > return engine; > } > > -static void kill_context(struct i915_gem_context *ctx) > +static void kill_engines(struct i915_gem_engines *engines) > { > struct i915_gem_engines_iter it; > struct intel_context *ce; > @@ -462,7 +463,7 @@ static void kill_context(struct i915_gem_context *ctx) > * However, we only care about pending requests, so only include > * engines on which there are incomplete requests. > */ > - for_each_gem_engine(ce, __context_engines_static(ctx), it) { > + for_each_gem_engine(ce, engines, it) { > struct intel_engine_cs *engine; > > if (intel_context_set_banned(ce)) > @@ -484,8 +485,37 @@ static void kill_context(struct i915_gem_context *ctx) > * the context from the GPU, we have to resort to a full > * reset. We hope the collateral damage is worth it. > */ > - __reset_context(ctx, engine); > + __reset_context(engines->ctx, engine); > + } > +} > + > +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); > + list_for_each_entry_safe(pos, next, &ctx->stale.engines, link) { > + if (!i915_sw_fence_await(&pos->fence)) > + continue; > + > + spin_unlock_irqrestore(&ctx->stale.lock, flags); > + > + kill_engines(pos); > + > + spin_lock_irqsave(&ctx->stale.lock, flags); > + 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); > +} > + > +static void kill_context(struct i915_gem_context *ctx) > +{ > + kill_stale_engines(ctx); > + kill_engines(__context_engines_static(ctx)); > } > > static void set_closed_name(struct i915_gem_context *ctx) > @@ -602,6 +632,9 @@ __create_context(struct drm_i915_private *i915) > ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL); > mutex_init(&ctx->mutex); > > + spin_lock_init(&ctx->stale.lock); > + INIT_LIST_HEAD(&ctx->stale.engines); > + > mutex_init(&ctx->engines_mutex); > e = default_engines(ctx); > if (IS_ERR(e)) { > @@ -1529,6 +1562,77 @@ 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) > @@ -1571,7 +1675,8 @@ set_engines(struct i915_gem_context *ctx, > if (!set.engines) > return -ENOMEM; > > - init_rcu_head(&set.engines->rcu); > + set.engines->ctx = ctx; > + > for (n = 0; n < num_engines; n++) { > struct i915_engine_class_instance ci; > struct intel_engine_cs *engine; > @@ -1631,7 +1736,8 @@ set_engines(struct i915_gem_context *ctx, > set.engines = rcu_replace_pointer(ctx->engines, set.engines, 1); > mutex_unlock(&ctx->engines_mutex); > > - call_rcu(&set.engines->rcu, free_engines_rcu); > + /* Keep track of old engine sets for kill_context() */ > + engines_idle_release(set.engines); > > return 0; > } > @@ -1646,7 +1752,6 @@ __copy_engines(struct i915_gem_engines *e) > if (!copy) > return ERR_PTR(-ENOMEM); > > - init_rcu_head(©->rcu); > for (n = 0; n < e->num_engines; n++) { > if (e->engines[n]) > copy->engines[n] = intel_context_get(e->engines[n]); > @@ -1890,7 +1995,8 @@ static int clone_engines(struct i915_gem_context *dst, > if (!clone) > goto err_unlock; > > - init_rcu_head(&clone->rcu); > + clone->ctx = dst; > + > for (n = 0; n < e->num_engines; n++) { > struct intel_engine_cs *engine; > > 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 017ca803ab47..8d996dde8046 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > @@ -20,6 +20,7 @@ > #include "gt/intel_context_types.h" > > #include "i915_scheduler.h" > +#include "i915_sw_fence.h" > > struct pid; > > @@ -30,7 +31,12 @@ struct intel_timeline; > struct intel_ring; > > struct i915_gem_engines { > - struct rcu_head rcu; > + union { > + struct rcu_head rcu; > + struct list_head link; > + }; > + struct i915_sw_fence fence; > + struct i915_gem_context *ctx; > unsigned int num_engines; > struct intel_context *engines[]; > }; > @@ -173,6 +179,11 @@ struct i915_gem_context { > * context in messages. > */ > char name[TASK_COMM_LEN + 8]; > + > + struct { > + struct spinlock lock; > + struct list_head engines; > + } stale; > }; > > #endif /* __I915_GEM_CONTEXT_TYPES_H__ */ > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c > index 51ba97daf2a0..a3d38e089b6e 100644 > --- a/drivers/gpu/drm/i915/i915_sw_fence.c > +++ b/drivers/gpu/drm/i915/i915_sw_fence.c > @@ -211,10 +211,21 @@ void i915_sw_fence_complete(struct i915_sw_fence *fence) > __i915_sw_fence_complete(fence, NULL); > } > > -void i915_sw_fence_await(struct i915_sw_fence *fence) > +bool i915_sw_fence_await(struct i915_sw_fence *fence) > { > - debug_fence_assert(fence); > - WARN_ON(atomic_inc_return(&fence->pending) <= 1); > + int pending; > + > + /* > + * It is only safe to add a new await to the fence while it has > + * not yet been signaled (i.e. there are still existing signalers). > + */ > + pending = atomic_read(&fence->pending); > + do { > + if (pending < 1) > + return false; > + } while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1)); > + > + return true; > } > > void __i915_sw_fence_init(struct i915_sw_fence *fence, > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h > index 19e806ce43bc..30a863353ee6 100644 > --- a/drivers/gpu/drm/i915/i915_sw_fence.h > +++ b/drivers/gpu/drm/i915/i915_sw_fence.h > @@ -91,7 +91,7 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence, > unsigned long timeout, > gfp_t gfp); > > -void i915_sw_fence_await(struct i915_sw_fence *fence); > +bool i915_sw_fence_await(struct i915_sw_fence *fence); > void i915_sw_fence_complete(struct i915_sw_fence *fence); > > static inline bool i915_sw_fence_signaled(const struct i915_sw_fence *fence) > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Regards, Tvrtko
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index cfaf5bbdbcab..3e82739bdbc0 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -270,7 +270,8 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx) if (!e) return ERR_PTR(-ENOMEM); - init_rcu_head(&e->rcu); + e->ctx = ctx; + for_each_engine(engine, gt, id) { struct intel_context *ce; @@ -450,7 +451,7 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce) return engine; } -static void kill_context(struct i915_gem_context *ctx) +static void kill_engines(struct i915_gem_engines *engines) { struct i915_gem_engines_iter it; struct intel_context *ce; @@ -462,7 +463,7 @@ static void kill_context(struct i915_gem_context *ctx) * However, we only care about pending requests, so only include * engines on which there are incomplete requests. */ - for_each_gem_engine(ce, __context_engines_static(ctx), it) { + for_each_gem_engine(ce, engines, it) { struct intel_engine_cs *engine; if (intel_context_set_banned(ce)) @@ -484,8 +485,37 @@ static void kill_context(struct i915_gem_context *ctx) * the context from the GPU, we have to resort to a full * reset. We hope the collateral damage is worth it. */ - __reset_context(ctx, engine); + __reset_context(engines->ctx, engine); + } +} + +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); + list_for_each_entry_safe(pos, next, &ctx->stale.engines, link) { + if (!i915_sw_fence_await(&pos->fence)) + continue; + + spin_unlock_irqrestore(&ctx->stale.lock, flags); + + kill_engines(pos); + + spin_lock_irqsave(&ctx->stale.lock, flags); + 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); +} + +static void kill_context(struct i915_gem_context *ctx) +{ + kill_stale_engines(ctx); + kill_engines(__context_engines_static(ctx)); } static void set_closed_name(struct i915_gem_context *ctx) @@ -602,6 +632,9 @@ __create_context(struct drm_i915_private *i915) ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL); mutex_init(&ctx->mutex); + spin_lock_init(&ctx->stale.lock); + INIT_LIST_HEAD(&ctx->stale.engines); + mutex_init(&ctx->engines_mutex); e = default_engines(ctx); if (IS_ERR(e)) { @@ -1529,6 +1562,77 @@ 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) @@ -1571,7 +1675,8 @@ set_engines(struct i915_gem_context *ctx, if (!set.engines) return -ENOMEM; - init_rcu_head(&set.engines->rcu); + set.engines->ctx = ctx; + for (n = 0; n < num_engines; n++) { struct i915_engine_class_instance ci; struct intel_engine_cs *engine; @@ -1631,7 +1736,8 @@ set_engines(struct i915_gem_context *ctx, set.engines = rcu_replace_pointer(ctx->engines, set.engines, 1); mutex_unlock(&ctx->engines_mutex); - call_rcu(&set.engines->rcu, free_engines_rcu); + /* Keep track of old engine sets for kill_context() */ + engines_idle_release(set.engines); return 0; } @@ -1646,7 +1752,6 @@ __copy_engines(struct i915_gem_engines *e) if (!copy) return ERR_PTR(-ENOMEM); - init_rcu_head(©->rcu); for (n = 0; n < e->num_engines; n++) { if (e->engines[n]) copy->engines[n] = intel_context_get(e->engines[n]); @@ -1890,7 +1995,8 @@ static int clone_engines(struct i915_gem_context *dst, if (!clone) goto err_unlock; - init_rcu_head(&clone->rcu); + clone->ctx = dst; + for (n = 0; n < e->num_engines; n++) { struct intel_engine_cs *engine; 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 017ca803ab47..8d996dde8046 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h @@ -20,6 +20,7 @@ #include "gt/intel_context_types.h" #include "i915_scheduler.h" +#include "i915_sw_fence.h" struct pid; @@ -30,7 +31,12 @@ struct intel_timeline; struct intel_ring; struct i915_gem_engines { - struct rcu_head rcu; + union { + struct rcu_head rcu; + struct list_head link; + }; + struct i915_sw_fence fence; + struct i915_gem_context *ctx; unsigned int num_engines; struct intel_context *engines[]; }; @@ -173,6 +179,11 @@ struct i915_gem_context { * context in messages. */ char name[TASK_COMM_LEN + 8]; + + struct { + struct spinlock lock; + struct list_head engines; + } stale; }; #endif /* __I915_GEM_CONTEXT_TYPES_H__ */ diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c index 51ba97daf2a0..a3d38e089b6e 100644 --- a/drivers/gpu/drm/i915/i915_sw_fence.c +++ b/drivers/gpu/drm/i915/i915_sw_fence.c @@ -211,10 +211,21 @@ void i915_sw_fence_complete(struct i915_sw_fence *fence) __i915_sw_fence_complete(fence, NULL); } -void i915_sw_fence_await(struct i915_sw_fence *fence) +bool i915_sw_fence_await(struct i915_sw_fence *fence) { - debug_fence_assert(fence); - WARN_ON(atomic_inc_return(&fence->pending) <= 1); + int pending; + + /* + * It is only safe to add a new await to the fence while it has + * not yet been signaled (i.e. there are still existing signalers). + */ + pending = atomic_read(&fence->pending); + do { + if (pending < 1) + return false; + } while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1)); + + return true; } void __i915_sw_fence_init(struct i915_sw_fence *fence, diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h index 19e806ce43bc..30a863353ee6 100644 --- a/drivers/gpu/drm/i915/i915_sw_fence.h +++ b/drivers/gpu/drm/i915/i915_sw_fence.h @@ -91,7 +91,7 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence, unsigned long timeout, gfp_t gfp); -void i915_sw_fence_await(struct i915_sw_fence *fence); +bool i915_sw_fence_await(struct i915_sw_fence *fence); void i915_sw_fence_complete(struct i915_sw_fence *fence); static inline bool i915_sw_fence_signaled(const struct i915_sw_fence *fence)
If we have a set of active engines marked as being non-persistent, we lose track of those if the user replaces those engines with I915_CONTEXT_PARAM_ENGINES. As part of our uABI contract is that non-persistent requests are terminated if they are no longer being tracked by the user's context (in order to prevent a lost request causing an untracked and so unstoppable GPU hang), we need to apply the same context cancellation upon changing engines. v2: Track stale engines[] so we only reap at context closure. v3: Tvrtko spotted races with closing contexts and set-engines, so add a veneer of kill-everything paranoia to clean up after losing a race. Fixes: a0e047156cde ("drm/i915/gem: Make context persistence optional") Testcase: igt/gem_ctx_peristence/replace Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 122 ++++++++++++++++-- .../gpu/drm/i915/gem/i915_gem_context_types.h | 13 +- drivers/gpu/drm/i915/i915_sw_fence.c | 17 ++- drivers/gpu/drm/i915/i915_sw_fence.h | 2 +- 4 files changed, 141 insertions(+), 13 deletions(-)