From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id CCA82FD4F1F for ; Tue, 10 Mar 2026 19:03:19 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 059AD10E2DB; Tue, 10 Mar 2026 19:03:18 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=lankhorst.se header.i=@lankhorst.se header.b="GYu4TCJo"; dkim-atps=neutral Received: from lankhorst.se (unknown [141.105.120.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 79A6C10E2D1; Tue, 10 Mar 2026 19:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lankhorst.se; s=default; t=1773169395; bh=Eb/85b5s3J1SrNnCYdrUNYgYfHqbz5dKd5RyBjycj1s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GYu4TCJoa4ULUkgwOPCoSzYTU/hGmCbORHB3EPACSqbtQO9G/LcLZO8om/Jfx8kEb 3wORaQz8RpyJryk1AAKzIV3CBmU7u8BjCpujvLPze860UkyzIjUInFtMZVdFXShbcC AmXEbnzh6SeBH7LOnbS5Nfx5tSijBDdldGgp/IPrlKyih4BM8Dz3lPilQxXRRHQ9n3 BBUyGQZuIBb3KX6S/TkgVILvICbS2vbkenCIS5qPTdxS3g1sK3cjXeFuedtWRBemIb nlkL6+PPi3cqFwYegjz49OGZYbRPlgbMlI+hJGgq8u6ylYGG6dIWzMjByf3z2JnaZR fCiMnEi/e31kw== Message-ID: <7774bff2-e101-4e59-9cfb-9f200e1caef9@lankhorst.se> Date: Tue, 10 Mar 2026 20:03:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 26/26] drm/i915/gt: Add a spinlock to prevent starvation of irq_work. To: Sebastian Andrzej Siewior Cc: intel-xe@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org References: <20260310115709.2276203-1-dev@lankhorst.se> <20260310115709.2276203-27-dev@lankhorst.se> <20260310172214.4lEOgGOl@linutronix.de> Content-Language: en-US From: Maarten Lankhorst In-Reply-To: <20260310172214.4lEOgGOl@linutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hey, Den 2026-03-10 kl. 18:22, skrev Sebastian Andrzej Siewior: > On 2026-03-10 12:57:08 [+0100], Maarten Lankhorst wrote: >> --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c >> +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c >> @@ -487,8 +490,11 @@ void intel_context_remove_breadcrumbs(struct intel_context *ce, >> if (release) >> intel_context_put(ce); >> >> - while (atomic_read(&b->signaler_active)) >> + while (atomic_read(&b->signaler_active)) { >> + spin_lock(&b->signaler_active_sync); >> + spin_unlock(&b->signaler_active_sync); >> cpu_relax(); > > Forgot to mention: This is fine on PREEMPT_RT but on !RT you might need > > spin_lock_irqsave(&b->signaler_active_sync, flags); > spin_unlock_irqrestore(&b->signaler_active_sync, flags); > > if the function can be called from !IRQ context which might be the case > due to the irqsave() earlier in this function. Yeah seems a bit of an oversight. I'll change it to use flags. Is it correct to assume that irq_work disables interrupts on !RT? Kind regards, ~Maarten Lankhorst