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 EAB8A165F08; Tue, 8 Oct 2024 12:29:38 +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=1728390579; cv=none; b=K/fwv1NBnAoidrhra1QN8/XTrCi1ykC+OM+C2A1nliev0IwZZrSHTS7/51iGqTPwOOjd1/QlLfb8iKFK6qR3DAA3DbZCG1W5uKYHfNs51ylFNZB1ERoELPwW3nGD/293ckV6YQdaKkEMJK7cQyZSxrbFAZq7nbNrn5qRgpAkjD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728390579; c=relaxed/simple; bh=SZpmYqhfSahMTDAEV/p73nzRoaL9SIh6nfpSmnLaloQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q//oTtCFM+mf+YgVgwC0+0sjSRiTFpNKXcH92fYZbYwLrXb0necLQbRd4eWYpVgOQWy8JDGpv6ikqQxdSoMNLn/0dZ2Q97VvSIe+MoautBaj1OOj+2F3MVXZUS7SRSU7lbgK9l1OA77jrrVBLCTImUiK26yL7bm8ydV6wBNThoU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LugYYQb0; 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="LugYYQb0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B404C4CEC7; Tue, 8 Oct 2024 12:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728390578; bh=SZpmYqhfSahMTDAEV/p73nzRoaL9SIh6nfpSmnLaloQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LugYYQb05gRk4NYpEAy4Bk21qFSjzsdCbHr46CQ4zz7ome/rEaBECKWQfHgHHGRZM Sb0QZtQFS2IoyLPWbdc22ywpnbO8JWRasK3F6985joOByIj6Nt2dcAIBLlnfp+28YL SgxmndsTBkHKFwROtbenfVemBwpwxGExXMJNiKbY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Krzysztof Piotr Oledzki , Heiner Kallweit , Wolfram Sang Subject: [PATCH 6.10 296/482] i2c: core: Lock address during client device instantiation Date: Tue, 8 Oct 2024 14:05:59 +0200 Message-ID: <20241008115659.930371333@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115648.280954295@linuxfoundation.org> References: <20241008115648.280954295@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-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiner Kallweit commit 8d3cefaf659265aa82b0373a563fdb9d16a2b947 upstream. Krzysztof reported an issue [0] which is caused by parallel attempts to instantiate the same I2C client device. This can happen if driver supports auto-detection, but certain devices are also instantiated explicitly. The original change isn't actually wrong, it just revealed that I2C core isn't prepared yet to handle this scenario. Calls to i2c_new_client_device() can be nested, therefore we can't use a simple mutex here. Parallel instantiation of devices at different addresses is ok, so we just have to prevent parallel instantiation at the same address. We can use a bitmap with one bit per 7-bit I2C client address, and atomic bit operations to set/check/clear bits. Now a parallel attempt to instantiate a device at the same address will result in -EBUSY being returned, avoiding the "sysfs: cannot create duplicate filename" splash. Note: This patch version includes small cosmetic changes to the Tested-by version, only functional change is that address locking is supported for slave addresses too. [0] https://lore.kernel.org/linux-i2c/9479fe4e-eb0c-407e-84c0-bd60c15baf74@ans.pl/T/#m12706546e8e2414d8f1a0dc61c53393f731685cc Fixes: caba40ec3531 ("eeprom: at24: Probe for DDR3 thermal sensor in the SPD case") Cc: stable@vger.kernel.org Tested-by: Krzysztof Piotr Oledzki Signed-off-by: Heiner Kallweit Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/i2c-core-base.c | 28 ++++++++++++++++++++++++++++ include/linux/i2c.h | 3 +++ 2 files changed, 31 insertions(+) --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -915,6 +915,27 @@ int i2c_dev_irq_from_resources(const str return 0; } +/* + * Serialize device instantiation in case it can be instantiated explicitly + * and by auto-detection + */ +static int i2c_lock_addr(struct i2c_adapter *adap, unsigned short addr, + unsigned short flags) +{ + if (!(flags & I2C_CLIENT_TEN) && + test_and_set_bit(addr, adap->addrs_in_instantiation)) + return -EBUSY; + + return 0; +} + +static void i2c_unlock_addr(struct i2c_adapter *adap, unsigned short addr, + unsigned short flags) +{ + if (!(flags & I2C_CLIENT_TEN)) + clear_bit(addr, adap->addrs_in_instantiation); +} + /** * i2c_new_client_device - instantiate an i2c device * @adap: the adapter managing the device @@ -962,6 +983,10 @@ i2c_new_client_device(struct i2c_adapter goto out_err_silent; } + status = i2c_lock_addr(adap, client->addr, client->flags); + if (status) + goto out_err_silent; + /* Check for address business */ status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client)); if (status) @@ -993,6 +1018,8 @@ i2c_new_client_device(struct i2c_adapter dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n", client->name, dev_name(&client->dev)); + i2c_unlock_addr(adap, client->addr, client->flags); + return client; out_remove_swnode: @@ -1004,6 +1031,7 @@ out_err: dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x (%d)\n", client->name, client->addr, status); + i2c_unlock_addr(adap, client->addr, client->flags); out_err_silent: if (need_put) put_device(&client->dev); --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -748,6 +748,9 @@ struct i2c_adapter { struct regulator *bus_regulator; struct dentry *debugfs; + + /* 7bit address space */ + DECLARE_BITMAP(addrs_in_instantiation, 1 << 7); }; #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)