From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27793156222; Mon, 16 Sep 2024 12:06:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726488413; cv=none; b=WFEV8meOcN5R+abC9cqgggLclVj9PoBPX3VWJqKOrFOciB5l83X1XNu3h0IY0sVvhO7/5XounXBe5aGw8960Pnexrgr9NcrnzxEuRZWC78P/J8JfsQ94dN2jY+EjwrdG74vsCg9Vm4rmqw/E75lLwpC9oFHKELf3GnRQtwfvtRc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726488413; c=relaxed/simple; bh=irGgRJXBUbo2ZYUkSFP9PdW70Oq1mP1juUVqJSyrgfU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WXY9SL9M0MtOaWLkYej/vi51AkWJqkYJzky5EbPFJDYfBYEtRgeBGS/lLPylV3RWuMdM1HnQcV5XgIjwWxmlYBzYwn8bhmmTJmgf6rSvY2xjudAXGjJ/Z4t2rWmvhfF6s/kEmJL14eJYSOmR2VXOG3uMB/s/cbEdnE4KDaSqyrs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PrSDOYdl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="PrSDOYdl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FE8BC4CEC4; Mon, 16 Sep 2024 12:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1726488413; bh=irGgRJXBUbo2ZYUkSFP9PdW70Oq1mP1juUVqJSyrgfU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PrSDOYdlLSU5nH7KEX56a4mmNYGM2bVAC3IMnicSnL2U7jb4WjQFFGobFn7FxpOPR IPCCJ3gexj3VR9hNDjuV0S1vFRQYRl1lwXXqVVzAssxpVSnIblfkZbYUyFq1/NMd2U 8iv+KtQwYypa+upH57cfAf+9SKCZaS4LQN81oNH4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tobias Jakobi , Harry Wentland , Mario Limonciello , Alex Deucher Subject: [PATCH 6.10 105/121] drm/amd/display: Avoid race between dcn35_set_drr() and dc_state_destruct() Date: Mon, 16 Sep 2024 13:44:39 +0200 Message-ID: <20240916114232.579597839@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240916114228.914815055@linuxfoundation.org> References: <20240916114228.914815055@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tobias Jakobi commit e835d5144f5ef78e4f8828c63e2f0d61144f283a upstream. dc_state_destruct() nulls the resource context of the DC state. The pipe context passed to dcn35_set_drr() is a member of this resource context. If dc_state_destruct() is called parallel to the IRQ processing (which calls dcn35_set_drr() at some point), we can end up using already nulled function callback fields of struct stream_resource. The logic in dcn35_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 Reviewed-by: Harry Wentland Signed-off-by: Mario Limonciello Signed-off-by: Alex Deucher (cherry picked from commit 0607a50c004798a96e62c089a4c34c220179dcb5) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c | 20 +++++++++------- 1 file changed, 12 insertions(+), 8 deletions(-) --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c @@ -1371,7 +1371,13 @@ void dcn35_set_drr(struct pipe_ctx **pip params.vertical_total_mid_frame_num = adjust.v_total_mid_frame_num; for (i = 0; i < num_pipes; i++) { - if ((pipe_ctx[i]->stream_res.tg != NULL) && pipe_ctx[i]->stream_res.tg->funcs) { + /* 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) { struct dc_crtc_timing *timing = &pipe_ctx[i]->stream->timing; struct dc *dc = pipe_ctx[i]->stream->ctx->dc; @@ -1384,14 +1390,12 @@ void dcn35_set_drr(struct pipe_ctx **pip num_frames = 2 * (frame_rate % 60); } } - 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); + 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); } } }