From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D542C606A320 for ; Tue, 10 Nov 2026 22:34:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SkoXzITV Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9507F10E078; Tue, 10 Nov 2026 22:34:14 +0000 (UTC) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7653410E078 for ; Tue, 10 Nov 2026 22:34:08 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1BF2042296; Tue, 10 Nov 2026 22:34:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D19A31F008A2; Tue, 10 Nov 2026 22:34:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794350048; bh=J+r92uiWfUl6vpuj6leqwuLO8DLMUkLk+rVSuQBZbKw=; h=From:Subject:Reply-To:To:In-Reply-To:References:Date; b=SkoXzITV3/mlchUumY8CBFekv9uk0rzBScCDmtPGlTan1tCQJ1mNTBPICbE/WxyGy w24Iwy0IXli1Lw1YXd+eJGP/gl6HTJe7xLwJjQym8zPNr78ReE9LRSr0jmBV7YjPNH DrWVfT41l6AWTo4D/9KVWois6vnMQatdJaCh4O4dxSn6mz/aQJlTkIR8NRTpEDk7/x UMbzL/7GW4RmL3UDKqxX6FCBbROcboH/n6dPHOJbS0UTCNpra0lcWvu80I3bivMEnq xMg5uxObO/RCB/u98C6prxTa3aTb7hAgI1qJBM0WNPT36/tmCnKKYOrrxmHVooLEAj pbgao/YQKBgsA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 1/3] drm/xe/forcewake: add delayed release with hysteresis To: "Zongyao Bai" , intel-xe@lists.freedesktop.org In-Reply-To: <20261110220542.432595-2-zongyao.bai@intel.com> References: <20261017031856.2723986-1-zongyao.bai@intel.com> <20261110220542.432595-1-zongyao.bai@intel.com> <20261110220542.432595-2-zongyao.bai@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 10 Nov 2026 22:34:07 +0000 X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "Intel-xe" X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 2 potential issues to consider: - [Medium] drm/xe: delayed forcewake domains stranded when rpm_get_if_active fails - [Low] drm/xe/forcewake: xe_force_wake_assert_held() passes on delayed domains -- commit 4a71af2399dc0153d2185a60b2aa48a76a02006c Author: Zongyao Bai drm/xe/forcewake: add delayed release with hysteresis This commit adds xe_force_wake_put_delay() and a delayed release worker to keep forcewake domains awake for a short hold period after their last reference is dropped. > diff --git a/drivers/gpu/drm/xe/xe_force_wake.c b/drivers/gpu/drm/xe/xe_f= orce_wake.c > index 197e2197bd0a3..d09d138c10840 100644 > --- a/drivers/gpu/drm/xe/xe_force_wake.c > +++ b/drivers/gpu/drm/xe/xe_force_wake.c [ ... ] > @@ -244,21 +307,101 @@ void xe_force_wake_put(struct xe_force_wake *fw, u= nsigned int fw_ref) > for_each_fw_domain_masked(domain, fw_ref, fw, tmp) { > xe_gt_assert(gt, domain->ref); > =20 > - if (!--domain->ref) { > + if (--domain->ref) > + continue; > + > + if (hold_ms && fw->delayed_enabled) { > + unsigned long hold =3D xe_force_wake_hold_jiffies(hold_ms); > + > + domain->hold_until =3D jiffies + hold; > + fw->delayed_domains |=3D BIT(domain->id); > + /* No-op if pending, the worker requeues for the latest hold. */ > + queue_delayed_work(system_percpu_wq, > + &fw->delayed_release_work, hold); > + } else { > sleep |=3D BIT(domain->id); > - domain_sleep(gt, domain); > } > } [Severity: Low] Does keeping BIT(domain->id) set in fw->awake_domains while a domain is in fw->delayed_domains cause xe_force_wake_assert_held() to pass even when no caller holds a reference? drivers/gpu/drm/xe/xe_force_wake.h:xe_force_wake_assert_held() { xe_gt_assert(fw->gt, domain !=3D XE_FORCEWAKE_ALL); xe_gt_assert(fw->gt, fw->awake_domains & domain); } During the delayed hold window, domain->ref is 0 and xe_force_wake_delayed_release_work() can put the domain to sleep on another CPU at any time, but xe_force_wake_assert_held() only checks fw->awake_domains & domain without excluding fw->delayed_domains. > + ack_fail =3D xe_force_wake_sleep_locked(fw, sleep); > spin_unlock_irqrestore(&fw->lock, flags); > =20 > + xe_force_wake_warn_sleep_fail(gt, ack_fail); > +} [ ... ] > +static void xe_force_wake_delayed_release_work(struct work_struct *work) > +{ > + struct xe_force_wake *fw =3D container_of(to_delayed_work(work), > + struct xe_force_wake, delayed_release_work); > + struct xe_gt *gt =3D fw->gt; > + struct xe_device *xe =3D gt_to_xe(gt); > + struct xe_force_wake_domain *domain; > + unsigned int tmp, expired =3D 0, ack_fail; > + unsigned long flags, next =3D 0; > + bool remaining =3D false; > + > + /* Never resume from here, the suspend flush settles delayed domains. */ > + if (!xe_pm_runtime_get_if_active(xe)) > + return; [Severity: Medium] Can returning early here without sleeping expired domains or requeuing fw->delayed_release_work leave fw->delayed_domains stranded awake? Although commit "drm/xe/forcewake: flush delayed release at power and teardown boundaries" flushes delayed domains in xe_gt_suspend() and xe_gt_runtime_suspend(), xe_pm_runtime_get_if_active() returns false as soon as rpm_suspend() sets dev->power.runtime_status to RPM_SUSPENDING. If xe_force_wake_delayed_release_work() runs while xe_pm_runtime_suspend() is in xe_pxp_pm_suspend(), xe_bo_evict_all(), or an earlier GT's suspend, and that step fails and jumps to out_resume, the remaining GTs are never flushed and runtime_status returns to RPM_ACTIVE with their delayed domains still awake and no worker pending, preventing C6 entry. In addition, when CONFIG_PM is disabled, pm_runtime_get_if_active() returns -EINVAL, so xe_pm_runtime_get_if_active() is always false and delayed domains are never released. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261110220542.4325= 95-1-zongyao.bai@intel.com?part=3D1