From patchwork Mon Mar 30 21:06:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11466333 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 89AD081 for ; Mon, 30 Mar 2020 21:06:58 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 53D6F20757 for ; Mon, 30 Mar 2020 21:06:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53D6F20757 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D6A126E4AA; Mon, 30 Mar 2020 21:06:57 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id C049A6E4AA for ; Mon, 30 Mar 2020 21:06:56 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 20745093-1500050 for multiple; Mon, 30 Mar 2020 22:06:49 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Mon, 30 Mar 2020 22:06:47 +0100 Message-Id: <20200330210647.3343-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915/gem: Utilize rcu iteration of context engines X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Chris Wilson Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Now that we can peek at GEM->engines[] and obtain a reference to them using RCU, do so for instances where we can safely iterate the potentially old copy of the engines. For setting, we can do this when we know the engine properties are copied over before swapping, so we know the new engines already have the global property and we update the old before they are discarded. For reading, we only need to be safe; as we do so on behalf of the user, their races are their own problem. Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 53 +++++++++++---------- 1 file changed, 27 insertions(+), 26 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index 50e7580f9337..b2f5eec59a37 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -757,21 +757,46 @@ __create_context(struct drm_i915_private *i915) return ERR_PTR(err); } +static inline struct i915_gem_engines * +__context_engines_await(const struct i915_gem_context *ctx) +{ + struct i915_gem_engines *engines; + + rcu_read_lock(); + do { + engines = rcu_dereference(ctx->engines); + GEM_BUG_ON(!engines); + + 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 int context_apply_all(struct i915_gem_context *ctx, int (*fn)(struct intel_context *ce, void *data), void *data) { struct i915_gem_engines_iter it; + struct i915_gem_engines *e; struct intel_context *ce; int err = 0; - for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) { + e = __context_engines_await(ctx); + for_each_gem_engine(ce, e, it) { err = fn(ce, data); if (err) break; } - i915_gem_context_unlock_engines(ctx); + i915_sw_fence_complete(&e->fence); return err; } @@ -1069,30 +1094,6 @@ static void cb_retire(struct i915_active *base) kfree(cb); } -static inline struct i915_gem_engines * -__context_engines_await(const struct i915_gem_context *ctx) -{ - struct i915_gem_engines *engines; - - rcu_read_lock(); - do { - engines = rcu_dereference(ctx->engines); - if (unlikely(!engines)) - break; - - 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; -} - I915_SELFTEST_DECLARE(static intel_engine_mask_t context_barrier_inject_fault); static int context_barrier_task(struct i915_gem_context *ctx, intel_engine_mask_t engines,