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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF0FBC83F21 for ; Mon, 28 Aug 2023 19:28:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233287AbjH1T2A (ORCPT ); Mon, 28 Aug 2023 15:28:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233254AbjH1T1b (ORCPT ); Mon, 28 Aug 2023 15:27:31 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B716CDC for ; Mon, 28 Aug 2023 12:27:07 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id ffacd0b85a97d-31aec0a1a8bso2255460f8f.0 for ; Mon, 28 Aug 2023 12:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1693250826; x=1693855626; 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=713tM2MtTN06BKtmpTKPtHYKAypTeU06f4AnOlNhYD4=; b=CSqa+pEoDUW2H0ZlraiWwUc3xrWOrJ1YaHmkjhFa1p/azSB734HWr7cU7e+myIPnxY qDsDy9RJtc6PWOZi806K/E6XsRbqhVy78B/oFwKTyW+g05lo+dhP4G62hGqrlQ641ZRU P8VP6sbAPFh7XXebDCKtOJ70udNb6SwiNfDapAw4WM4QHiBs1L6MYTO4T/+WXxLsQzk0 zIDoQGuZovksV9kVbawJ4xMgU2RlWI4uFaqB0yceUpKqZgcbSbYm5R1v8e88gGNG0KjH a5g9KaWoA3XNQ1D9zdItbOL4waj9PwpuPKgLNZQMhF8maGHr7j0ai4dCzdIUHby5GJf2 Rccg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693250826; x=1693855626; 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=713tM2MtTN06BKtmpTKPtHYKAypTeU06f4AnOlNhYD4=; b=YN56UixKT38j8DeH+LYtQbgMD7skc1N1XiGdzaOXHMW8vbN6zC5pmVNB/vNEfCR9YV BTxBQAo7s19erGMhjEhSaAMXdxus4yQBvVOhGilaZcLJmiEmzyIUYZen2R/jSAhV4cp+ PyCz+gikDycaejzIGZhj1Zzy2bPAbfT5bWCaVTPgzgqOVBkZ6kykROib8ASwA8+0T8AV wy3EMUR/Gf3D6aAWBwEzjsu7PWjJk8niTiEtNySlE9trWi1VXVaMzQfP6NRSIrC4o74D Ga3tVR7tArVScwacpMtFZMbNZc766Cua0Hb0E69coHwkeHOhcNtkki7xqEJ0P4+Cj18J meFg== X-Gm-Message-State: AOJu0YwvNHHJC8gscyQSw4YuiYjsrgdT5aebYLTjpFZ9ldTbQsqSOOpB 0tSiA/btZTX1OnRnBzwMbHFkzhjxEw0Ho5Asf2Q= X-Google-Smtp-Source: AGHT+IFP03AKHAfr/hAQD0gGF3wtYUFTciEZ8PKvTMJRFIBUMmxXBs7iwRUVJNseZQVqoKpOwBLzaw== X-Received: by 2002:adf:e682:0:b0:319:8c99:989a with SMTP id r2-20020adfe682000000b003198c99989amr369735wrm.8.1693250825898; Mon, 28 Aug 2023 12:27:05 -0700 (PDT) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:8bd:7f16:d368:115f]) by smtp.gmail.com with ESMTPSA id i20-20020a5d5234000000b003141f96ed36sm11435319wra.0.2023.08.28.12.27.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Aug 2023 12:27:05 -0700 (PDT) From: Bartosz Golaszewski To: Andy Gross , Bjorn Andersson , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Arnd Bergmann , Alex Elder , Srini Kandagatla Cc: kernel@quicinc.com, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Bartosz Golaszewski Subject: [PATCH 03/11] firmware: qcom-scm: atomically assign and read the global __scm pointer Date: Mon, 28 Aug 2023 21:24:59 +0200 Message-Id: <20230828192507.117334-4-bartosz.golaszewski@linaro.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230828192507.117334-1-bartosz.golaszewski@linaro.org> References: <20230828192507.117334-1-bartosz.golaszewski@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Checking for the availability of SCM bridge can happen from any context. It's only by chance that we haven't run into concurrency issues but with the upcoming SHM Bridge driver that will be initiated at the same initcall level, we need to assure the assignment and readback of the __scm pointer is atomic. Signed-off-by: Bartosz Golaszewski --- drivers/firmware/qcom_scm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c index 980fcfa20b9f..422de70faff8 100644 --- a/drivers/firmware/qcom_scm.c +++ b/drivers/firmware/qcom_scm.c @@ -1331,7 +1331,7 @@ static int qcom_scm_find_dload_address(struct device *dev, u64 *addr) */ bool qcom_scm_is_available(void) { - return !!__scm; + return !!READ_ONCE(__scm); } EXPORT_SYMBOL(qcom_scm_is_available); @@ -1477,8 +1477,8 @@ static int qcom_scm_probe(struct platform_device *pdev) if (ret) return ret; - __scm = scm; - __scm->dev = &pdev->dev; + scm->dev = &pdev->dev; + WRITE_ONCE(__scm, scm); init_completion(&__scm->waitq_comp); -- 2.39.2