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 101CBCD13CF for ; Mon, 2 Sep 2024 15:44:23 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AD88C10E095; Mon, 2 Sep 2024 15:44:22 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="YoMrToQM"; dkim-atps=neutral Received: from mail-ej1-f47.google.com (mail-ej1-f47.google.com [209.85.218.47]) by gabe.freedesktop.org (Postfix) with ESMTPS id 157EB10E336; Mon, 2 Sep 2024 14:43:47 +0000 (UTC) Received: by mail-ej1-f47.google.com with SMTP id a640c23a62f3a-a866cea40c4so494623366b.0; Mon, 02 Sep 2024 07:43:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1725288225; x=1725893025; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=yFRFdizmhc2CJwy4/CKQA005aAYjoT9/YpO+LeBpeuY=; b=YoMrToQM2O9BsASmmW1RhoYyH1dalzRRMWaY3J4itcS8nUFYDGOcikXc34kWox7Xq3 ZOL3kyY197lze7c/ztQ1GM2QismKbTM+Xv36bDy3BalI2aNAZl6n1EoE0uuG/4405fye AJLrFhLnfkmyfIB3fGragHQCVRoXuQ5A/dR/O3JlvczvONtqoMrw/X7hhc0uysmxdBuC pzg3po4/XcGYDDIl3qQxODa4PX/gsioqNtVpHGPy6GPgUBmFIkMm5qjASatjng7x9SJi NS6/lgEaHQN1PfqVOnvyPbmTlrMgOOOx7DrxZnSTshRJOkO9YEmCeAOWrGyMdVp4/TJ1 KUOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725288225; x=1725893025; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=yFRFdizmhc2CJwy4/CKQA005aAYjoT9/YpO+LeBpeuY=; b=CGdS4CvCBUjfav6NJK5oTh5emd6eYiU3GCEB095F5a0j3j7sPvFf9HO2cmcZhsN0vQ eUSvjtAntkgGfsZKRJAEe3BPOIwDwB9KGjkDTCfC40QnGCNUBh+eaF8PrsftHFeHuLGo sM0aT0HnUJrnpPnLAOK9RGv07FpzySkCdsdqZN77nZGcS5sfEJC1kDOjgmIQ4VaJj3eR 32KcOOyjbtpNDGackA9to7LbovfR9w4NnJnFNsem5mWpwtMfcWk4du4WN4U1FiqoRoVV B7mP4MJKlCMSMxns575wZZ6L/rMaklUikcYVgn8LvNYnA5hci3z1vxDUSRaZlch/ysRk fBBg== X-Forwarded-Encrypted: i=1; AJvYcCUi2lQpKS1+WhyLxRMEAyMzyYtsd3GOWq9iH2kM7qts6mztNQZt+q/Bld1m4t8K3Q+9oKAzKIBR9Hwh@lists.freedesktop.org, AJvYcCWmwF+nNwxk58X/cVEzocJCpa7/JU9j3iXDlcmbe4lZpuSDc7Mr5RINNssDDGRUBc/lvZs8o1wd@lists.freedesktop.org X-Gm-Message-State: AOJu0YwcENaX+/XpDQNgCMoV3FUZVGu5sa9WbaUqXzIJYbLMcEBXU5cX I/l3Y/fcAsVFy2F6RZULdD7xSMASG/B0YGt1qFsUTeFVyUxoaNrX X-Google-Smtp-Source: AGHT+IFVrmcQ2LyLLYhiHo5LRdWuFIggl65+Wa6I1kVeqYevDcItonWteNGDfQxRBC1yUAzXhRpMfg== X-Received: by 2002:a17:906:f5a8:b0:a7a:9226:6511 with SMTP id a640c23a62f3a-a8a1d3268cemr29177566b.31.1725288224997; Mon, 02 Sep 2024 07:43:44 -0700 (PDT) Received: from localhost.localdomain ([31.19.114.250]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a89891968e9sm563655266b.120.2024.09.02.07.43.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2024 07:43:44 -0700 (PDT) From: raoul.van.rueschen@gmail.com To: tjakobi@math.uni-bielefeld.de Cc: Rodrigo.Siqueira@amd.com, Xinhui.Pan@amd.com, airlied@gmail.com, alexander.deucher@amd.com, amd-gfx@lists.freedesktop.org, christian.koenig@amd.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, harry.wentland@amd.com, linux-kernel@vger.kernel.org, mario.limonciello@amd.com, sunpeng.li@amd.com, raoul.van.rueschen@gmail.com Subject: Re: [PATCH 1/2] drm/amd/display: Avoid race between dcn10_set_drr() and dc_state_destruct() Date: Mon, 2 Sep 2024 16:43:36 +0200 Message-ID: <20240902144337.18223-1-raoul.van.rueschen@gmail.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <7b9dbbbb1e6a3aa6d7a4d9367d44d18ddd947158.1725269643.git.tjakobi@math.uni-bielefeld.de> References: <7b9dbbbb1e6a3aa6d7a4d9367d44d18ddd947158.1725269643.git.tjakobi@math.uni-bielefeld.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Mon, 02 Sep 2024 15:44:22 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" > From: Tobias Jakobi > > dc_state_destruct() nulls the resource context of the DC state. The > pipe > context passed to dcn10_set_drr() is a member of this resource > context. > > If dc_state_destruct() is called parallel to the IRQ processing > (which > calls dcn10_set_drr() at some point), we can end up using already > nulled > function callback fields of struct stream_resource. > > The logic in dcn10_set_drr() already tries to avoid this, by checking > tg > against NULL. But if the nulling happens exactly after the NULL check > and > before the next access, then we get a race. > > Avoid this by copying tg first to a local variable, and then use this > variable for all the operations. This should work, as long as nobody > frees the resource pool where the timing generators live. > > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3142 > Fixes: 06ad7e164256 ("drm/amd/display: Destroy DC context while > keeping DML and DML2") > Signed-off-by: Tobias Jakobi > --- > .../amd/display/dc/hwss/dcn10/dcn10_hwseq.c | 20 +++++++++++------ > -- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c > b/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c > index 3306684e805a..da8f2cb3c5db 100644 > --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c > +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c > @@ -3223,15 +3223,19 @@ void dcn10_set_drr(struct pipe_ctx > **pipe_ctx, > * as well. > */ > for (i = 0; i < num_pipes; i++) { > - if ((pipe_ctx[i]->stream_res.tg != NULL) && > pipe_ctx[i]->stream_res.tg->funcs) { > - if (pipe_ctx[i]->stream_res.tg->funcs- > >set_drr) > - pipe_ctx[i]->stream_res.tg->funcs- > >set_drr( > - pipe_ctx[i]->stream_res.tg, > ¶ms); > + /* dc_state_destruct() might null the stream > resources, so fetch tg > + * here first to avoid a race condition. The > lifetime of the pointee > + * itself (the timing_generator object) is not a > problem here. > + */ > + struct timing_generator *tg = pipe_ctx[i]- > >stream_res.tg; > + > + if ((tg != NULL) && tg->funcs) { > + if (tg->funcs->set_drr) > + tg->funcs->set_drr(tg, ¶ms); > if (adjust.v_total_max != 0 && > adjust.v_total_min != 0) > - if (pipe_ctx[i]->stream_res.tg- > >funcs->set_static_screen_control) > - pipe_ctx[i]->stream_res.tg- > >funcs->set_static_screen_control( > - pipe_ctx[i]- > >stream_res.tg, > - event_triggers, > num_frames); > + if (tg->funcs- > >set_static_screen_control) > + tg->funcs- > >set_static_screen_control( > + tg, event_triggers, > num_frames); > } > } > } This fixes full system freezes when taking screenshots at low framerates with VRR enabled on an RX 7900 XTX. Tested-by: Raoul van Rüschen