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 4F0E11547C4; Mon, 16 Sep 2024 12:06:50 +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=1726488410; cv=none; b=RyfZD55ITkT3LNQLN+CAZzMnFr55xBP8x6irqf20B1uvmJZ4oxYsC9cYrEPkdczp8SQBVnQP+h7oFBqcut5vdXq9OlyXnc6WBVViyOezzgfYNFIAxAflYP+LxbaGqxM/c43tKQAi2dJfIbNY8pBx+5IahnA9Uv0a8bLTJOxrXKw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726488410; c=relaxed/simple; bh=iXu+Ij00PocWuOafB4ddgiBUeelJtmQgwQJG1z3odfo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=T7FNfkQEDiH4wLE16xmdv4wOjyCyXe7KEZAcCMhg0EFb9mk1JFR8bOain7dVaDOnMTLh+jNS2A1rvA/ZdrLz1ld1lZaTTFsTZme/hXCxq9pB33c33Jwkfex+fxys8EVj3Jd9aojWkAAgNZ7cVBjjf9+JXW2TNhiDBIwBp9ZOevE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JE3g9psr; 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="JE3g9psr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C465FC4CEC4; Mon, 16 Sep 2024 12:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1726488410; bh=iXu+Ij00PocWuOafB4ddgiBUeelJtmQgwQJG1z3odfo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JE3g9psrzvQZyupdVzIYwtY5ZFeou3tW9DThyDUlDdk2/5HKpo+m2/qLxW0L3sKeJ 2uNOBdBvOPKeIw30x71GKl4XqthXQlP7YljVsXZdmyu6OhRSjbdcc+9Exyu/fmAzii Mef19Q5gA2okiF8RkdcVgsKPknEZ62CycId0FoFY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tobias Jakobi , =?UTF-8?q?Raoul=20van=20R=C3=BCschen?= , Christopher Snowhill , Harry Wentland , Sefa Eyeoglu , Mario Limonciello , Alex Deucher Subject: [PATCH 6.10 104/121] drm/amd/display: Avoid race between dcn10_set_drr() and dc_state_destruct() Date: Mon, 16 Sep 2024 13:44:38 +0200 Message-ID: <20240916114232.550416383@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tobias Jakobi commit a7aeb03888b92304e2fc7d4d1c242f54a312561b upstream. 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 Tested-by: Raoul van Rüschen Tested-by: Christopher Snowhill Reviewed-by: Harry Wentland Tested-by: Sefa Eyeoglu Signed-off-by: Mario Limonciello Signed-off-by: Alex Deucher (cherry picked from commit a3cc326a43bdc48fbdf53443e1027a03e309b643) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c | 20 +++++++++------- 1 file changed, 12 insertions(+), 8 deletions(-) --- 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 **pip * 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); } } }