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[2620:137:e000::1:20]) by mx.google.com with ESMTP id w16-20020a05640234d000b0046314dd20a0si15389679edc.3.2022.12.14.06.39.52; Wed, 14 Dec 2022 06:40:25 -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=@marcan.st header.s=default header.b=IJBCeFCQ; 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=QUARANTINE sp=QUARANTINE dis=NONE) header.from=marcan.st Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238501AbiLNOaw (ORCPT + 99 others); Wed, 14 Dec 2022 09:30:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238517AbiLNOar (ORCPT ); Wed, 14 Dec 2022 09:30:47 -0500 Received: from mail.marcansoft.com (marcansoft.com [212.63.210.85]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7533F2252A for ; Wed, 14 Dec 2022 06:30:44 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sendonly@marcansoft.com) by mail.marcansoft.com (Postfix) with ESMTPSA id CAFB44203C; Wed, 14 Dec 2022 14:30:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=marcan.st; s=default; t=1671028241; bh=l+loTAS240QxDlt5drk5S5kcxptCa1dPnxhdg+DTW3U=; h=From:To:Cc:Subject:Date; b=IJBCeFCQH+TjndfqhW2YKGwN35jxyrebppxh1BAD9aW1t6mE8Rlk+WsJsPvbVKc9W WE0gZdAqDHMTYTcbzTuM9MPy3ZnAggFrY0Rx9RVFnYwyM++hyM2fx4dYFk9WYBiTUL oIynwVHHTREcP2MX0cFkmNgYMvEk4sodUvLvrDzDZlCsGtYamqRD4usFnCgEWwK0O4 Vzwpg1uD9V9DWG7hkGcug+H64jkIbWiAcBt7FTiwXAPXOVa4LrAQ64L5noO5Lxt/h7 xvxOcr536nEQmKA85VB1Jwc8qb7MZFsuGpqqeoMrwxv6lkA3xzk2FS8NmCOdTMJ31T 4OifBSZLzDcSA== From: Hector Martin To: Srinivas Kandagatla Cc: Sven Peter , Alyssa Rosenzweig , asahi@lists.linux.dev, linux-kernel@vger.kernel.org, Hector Martin Subject: [PATCH] nvmem: core: Fix race in nvmem_register() Date: Wed, 14 Dec 2022 23:29:53 +0900 Message-Id: <20221214142952.9372-1-marcan@marcan.st> X-Mailer: git-send-email 2.35.1 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,SPF_HELO_NONE,SPF_PASS autolearn=ham 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?1752200721715143224?= X-GMAIL-MSGID: =?utf-8?q?1752200721715143224?= nvmem_register() currently registers the device before adding the nvmem cells, which creates a race window where consumers may find the nvmem device (and not get PROBE_DEFERred), but then fail to find the cells and error out. Move device registration to the end of nvmem_register(), to close the race. Observed when the stars line up on Apple Silicon machines with the (not yet upstream, but trivial) spmi nvmem driver and the macsmc-rtc client: [ 0.487375] macsmc-rtc macsmc-rtc: error -ENOENT: Failed to get rtc_offset NVMEM cell Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers") Signed-off-by: Hector Martin Reviewed-by: Eric Curtin --- drivers/nvmem/core.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) -- 2.35.1 diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 321d7d63e068..d255feca5e17 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -837,20 +837,16 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); - rval = device_register(&nvmem->dev); - if (rval) - goto err_put_device; - if (nvmem->nkeepout) { rval = nvmem_validate_keepouts(nvmem); if (rval) - goto err_device_del; + return ERR_PTR(rval); } if (config->compat) { rval = nvmem_sysfs_setup_compat(nvmem, config); if (rval) - goto err_device_del; + return ERR_PTR(rval); } if (config->cells) { @@ -867,19 +863,21 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (rval) goto err_remove_cells; + rval = device_register(&nvmem->dev); + if (rval) + goto err_put_device; + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem); return nvmem; +err_put_device: + put_device(&nvmem->dev); err_remove_cells: nvmem_device_remove_all_cells(nvmem); 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); return ERR_PTR(rval); }