From b97090575ed27f8a23cc8f8ace642d5a8ea59206 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 10 Aug 2021 15:05:23 +0200 Subject: [PATCH] drm/i915: Use locked access to ctx->engines in set_priority This essentially reverts commit 89ff76bf9b3b0b86e6bbe344bd6378d8661303fc Author: Chris Wilson Date: Thu Apr 2 13:42:18 2020 +0100 drm/i915/gem: Utilize rcu iteration of context engines Note that the other use of __context_engines_await have disappeard in the following commits: ccbc1b97948a ("drm/i915/gem: Don't allow changing the VM on running contexts (v4)") c7a71fc8ee04 ("drm/i915: Drop getparam support for I915_CONTEXT_PARAM_ENGINES") 4a766ae40ec8 ("drm/i915: Drop the CONTEXT_CLONE API (v2)") None of these have any business to optimize their engine lookup with rcu, unless extremely convincing benchmark data and a solid analysis why we can't make that workload (whatever it is that does) faster with a proper design fix. Also since there's only one caller of context_apply_all left and it's really just a loop, inline it and then inline the lopp body too. This is how all other callers that take the engine lock loop over engines, it's much simpler. Reviewed-by: Jason Ekstrand Signed-off-by: Daniel Vetter Cc: Chris Wilson Cc: Mika Kuoppala Cc: Daniel Vetter Cc: Jason Ekstrand Cc: Tvrtko Ursulin Cc: Joonas Lahtinen Cc: Matthew Brost Link: https://patchwork.freedesktop.org/patch/msgid/20210810130523.1972031-1-daniel.vetter@ffwll.ch --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 72 ++++----------------- 1 file changed, 14 insertions(+), 58 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index dbaeb924a437..fd169cf2f75a 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -1284,49 +1284,6 @@ static int __context_set_persistence(struct i915_gem_context *ctx, bool state) return 0; } -static inline struct i915_gem_engines * -__context_engines_await(const struct i915_gem_context *ctx, - bool *user_engines) -{ - struct i915_gem_engines *engines; - - rcu_read_lock(); - do { - engines = rcu_dereference(ctx->engines); - GEM_BUG_ON(!engines); - - if (user_engines) - *user_engines = i915_gem_context_user_engines(ctx); - - /* successful await => strong mb */ - if (unlikely(!i915_sw_fence_await(&engines->fence))) - continue; - - if (likely(engines == rcu_access_pointer(ctx->engines))) - break; - - i915_sw_fence_complete(&engines->fence); - } while (1); - rcu_read_unlock(); - - return engines; -} - -static void -context_apply_all(struct i915_gem_context *ctx, - void (*fn)(struct intel_context *ce, void *data), - void *data) -{ - struct i915_gem_engines_iter it; - struct i915_gem_engines *e; - struct intel_context *ce; - - e = __context_engines_await(ctx, NULL); - for_each_gem_engine(ce, e, it) - fn(ce, data); - i915_sw_fence_complete(&e->fence); -} - static struct i915_gem_context * i915_gem_create_context(struct drm_i915_private *i915, const struct i915_gem_proto_context *pc) @@ -1776,23 +1733,11 @@ set_persistence(struct i915_gem_context *ctx, return __context_set_persistence(ctx, args->value); } -static void __apply_priority(struct intel_context *ce, void *arg) -{ - struct i915_gem_context *ctx = arg; - - if (!intel_engine_has_timeslices(ce->engine)) - return; - - if (ctx->sched.priority >= I915_PRIORITY_NORMAL && - intel_engine_has_semaphores(ce->engine)) - intel_context_set_use_semaphores(ce); - else - intel_context_clear_use_semaphores(ce); -} - static int set_priority(struct i915_gem_context *ctx, const struct drm_i915_gem_context_param *args) { + struct i915_gem_engines_iter it; + struct intel_context *ce; int err; err = validate_priority(ctx->i915, args); @@ -1800,7 +1745,18 @@ static int set_priority(struct i915_gem_context *ctx, return err; ctx->sched.priority = args->value; - context_apply_all(ctx, __apply_priority, ctx); + + for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) { + if (!intel_engine_has_timeslices(ce->engine)) + continue; + + if (ctx->sched.priority >= I915_PRIORITY_NORMAL && + intel_engine_has_semaphores(ce->engine)) + intel_context_set_use_semaphores(ce); + else + intel_context_clear_use_semaphores(ce); + } + i915_gem_context_unlock_engines(ctx); return 0; } -- 2.20.1