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[2620:137:e000::1:20]) by mx.google.com with ESMTP id p16-20020a170902b09000b001965acaade8si555040plr.24.2023.01.27.02.42.13; Fri, 27 Jan 2023 02:42:25 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=HDW24eJJ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232191AbjA0Kk6 (ORCPT + 99 others); Fri, 27 Jan 2023 05:40:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232119AbjA0Kkk (ORCPT ); Fri, 27 Jan 2023 05:40:40 -0500 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 731977DB8 for ; Fri, 27 Jan 2023 02:40:31 -0800 (PST) Received: by mail-wm1-x336.google.com with SMTP id c10-20020a05600c0a4a00b003db0636ff84so3143377wmq.0 for ; Fri, 27 Jan 2023 02:40:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; 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=GdVhqoNMJZ7VRQato0f6F3FYR5fTivzxS5e1+eryPnY=; b=HDW24eJJdhwhV+CVT0ICQs/7fTg5iROOF/oAT2IWNdOit9oQq+6DY/kJ9JcNAjZqxD AwrE5rtjUnFMYYNQZBYYBEZfDnPmWEvAF2bLGLLEcgwWNlY1Iht+TSQJdZsR6xmy/L8J BNfZyv7af9V+7kov+7ZUCpbAxlQNVTQHzS/HgHvU2Xgove76KNh7I4FjHTttuqV2YGwx Ezwh+fSWe01rL50JV3EPYJRFPIGn10emy4OuO4Lmnn/Pyg1Yz06lDh4X4bhnAQ51kixG 6STeQ1nZqsLChC7rSPxbInFPWfcGQA2x2BCEZCZCCA5nxkj+xT8h6rqFzt8uBsBUUdis CmTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=GdVhqoNMJZ7VRQato0f6F3FYR5fTivzxS5e1+eryPnY=; b=BBLRroVdFnZujjyB2O8ylxGdJOxtLOuAg0yEtIW4pdj6Cv9HCuvEPm5zySQaIVhDr0 SDhDFAv+6LJ88QAsQhbbU3Qpo3peK01WYc8KZH2WzkICeeNslv0uVryXOSpVHaBe1ebi OZPyzYtHxN6aHCHeTopf9P+YboQfI9cTjyuL11SevdwJfIOHKdpvKRnD6ryrBkxAFzcF RUFnfl43VvhN2eNX1Z5s5Yu5j7fyXJ6Bs6Bw0ugsPml4XJa2xIVbf2Z8AGXJKP1jpbJN ahDp89rCGEtHvqJ4U1ifpJGMWTTPr+5YFs/mcZSkJQ9amn1NVeVeJ9CymIbNX0rIVWZ4 Y4Ng== X-Gm-Message-State: AO0yUKV5GexQhe1/ErB7h5t1ZFEGMqpmBxKQLsFRpJ7dUeSaKGheAxNq zpYSuDsdJSjZ/nBUVxMO/n2TXw== X-Received: by 2002:a05:600c:707:b0:3dc:3577:fdb2 with SMTP id i7-20020a05600c070700b003dc3577fdb2mr1963492wmn.5.1674816030030; Fri, 27 Jan 2023 02:40:30 -0800 (PST) Received: from localhost.localdomain ([5.133.47.210]) by smtp.gmail.com with ESMTPSA id q9-20020a1ce909000000b003dc34edacf8sm1619787wmc.31.2023.01.27.02.40.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Jan 2023 02:40:29 -0800 (PST) From: Srinivas Kandagatla To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, "Russell King (Oracle)" , stable@vger.kernel.org, Srinivas Kandagatla Subject: [PATCH 06/10] nvmem: core: fix registration vs use race Date: Fri, 27 Jan 2023 10:40:11 +0000 Message-Id: <20230127104015.23839-7-srinivas.kandagatla@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230127104015.23839-1-srinivas.kandagatla@linaro.org> References: <20230127104015.23839-1-srinivas.kandagatla@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756172014662797513?= X-GMAIL-MSGID: =?utf-8?q?1756172014662797513?= From: "Russell King (Oracle)" The i.MX6 CPU frequency driver sometimes fails to register at boot time due to nvmem_cell_read_u32() sporadically returning -ENOENT. This happens because there is a window where __nvmem_device_get() in of_nvmem_cell_get() is able to return the nvmem device, but as cells have been setup, nvmem_find_cell_entry_by_node() returns NULL. The occurs because the nvmem core registration code violates one of the fundamental principles of kernel programming: do not publish data structures before their setup is complete. Fix this by making nvmem core code conform with this principle. Cc: stable@vger.kernel.org Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers") Signed-off-by: Russell King (Oracle) Signed-off-by: Srinivas Kandagatla --- drivers/nvmem/core.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index ac77a019aed7..e92c6f1aadbb 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -832,22 +832,16 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) nvmem->dev.groups = nvmem_dev_groups; #endif - dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); - - rval = device_add(&nvmem->dev); - if (rval) - goto err_put_device; - if (nvmem->nkeepout) { rval = nvmem_validate_keepouts(nvmem); if (rval) - goto err_device_del; + goto err_put_device; } if (config->compat) { rval = nvmem_sysfs_setup_compat(nvmem, config); if (rval) - goto err_device_del; + goto err_put_device; } if (config->cells) { @@ -864,6 +858,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (rval) goto err_remove_cells; + dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); + + rval = device_add(&nvmem->dev); + if (rval) + goto err_remove_cells; + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem); return nvmem; @@ -873,8 +873,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) err_teardown_compat: if (config->compat) nvmem_sysfs_remove_compat(nvmem, config); -err_device_del: - device_del(&nvmem->dev); err_put_device: put_device(&nvmem->dev);