From nobody Fri Dec 19 14:21:08 2025 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 A9B95C83F17 for ; Mon, 28 Aug 2023 19:28:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233480AbjH1T2M (ORCPT ); Mon, 28 Aug 2023 15:28:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233269AbjH1T1b (ORCPT ); Mon, 28 Aug 2023 15:27:31 -0400 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60D9ACD8 for ; Mon, 28 Aug 2023 12:27:07 -0700 (PDT) Received: by mail-wm1-x32b.google.com with SMTP id 5b1f17b1804b1-401d2e11dacso1808535e9.0 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=gTf1wAF/4WGenaCzv/ptfQgVaC2Tji+LUE5kE9D8rft0U4yh7gA+JbfpNarwZrGE1a jMCzZQ/kmkqpk1oR6w+SwE3Ih5rog6b+E/VrXIgCF6A0i4yvuFhjML1hvVD9sGY92jkP z9fwWYJQLoymrLsUf8r9y7TGiENscW9G92TLxy95awG9ylGZv8zxMJgKev2OgqfBtL1J Cskr+g4cmaAy0G1KE+GSVWtE0j9G9b+dzex3BYwUlimjF4rRQBlVht4MNvIvu9P8mXfL 8MHbKPs1r/YWVvH6DD7e7e2TxTlATr4MIVSosG5r7vOdRghDuTlc/+SBxKXc3t3dJO92 np2w== X-Gm-Message-State: AOJu0YzHIuWsXMFUsuIVfCiBwsoh+KaMTqoA6xL58yDYVpdTw94S2Zr7 kCs9ILsN/fQF55lVOS+lGQz9oQ== 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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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); =20 @@ -1477,8 +1477,8 @@ static int qcom_scm_probe(struct platform_device *pde= v) if (ret) return ret; =20 - __scm =3D scm; - __scm->dev =3D &pdev->dev; + scm->dev =3D &pdev->dev; + WRITE_ONCE(__scm, scm); =20 init_completion(&__scm->waitq_comp); =20 --=20 2.39.2