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 A31431DF24B; Tue, 8 Oct 2024 13:29:15 +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=1728394155; cv=none; b=Zk1bRviB6YekCwP/JGILk+UtjKtu7vjOU9M/ONFYDXHcR4yfbZVT75ZlXUavJ6wh2CS23tcvhgZSS7oZIuVdILZl/oJlbKTISIszqPnVxdXqgw4wuA8ZiXb3OizoRt+A+C1Ux4K8Sv25qQKkIbuvcVW774YTAKVWrdZaCSZtgOo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728394155; c=relaxed/simple; bh=hYOXOxzjIULIPOvXWU12v5HeCpBmtEvaRgNSgdv6NTI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=asG4SV881XX9DRXTjIKLGP0ds9Nl7gdI8zvG9PgNAe0Hry3Zg3EXh8jus16Yg1POBxWu7c6P27QbhpoewHEWlpSbG/YmNHy/ScQbwnGq18u+HqZqdzT7w/qhF8z5yg6XAwnCSr1NJcjcISsapXqYDp0CftfasvBQygz6mHaXdHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kUNqt+TK; 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="kUNqt+TK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1200EC4CECC; Tue, 8 Oct 2024 13:29:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728394155; bh=hYOXOxzjIULIPOvXWU12v5HeCpBmtEvaRgNSgdv6NTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kUNqt+TKnwoNluZb8BD/dgySfJ4KmK0bvKtv3UEzOphbOgGNi+8sThxlwhVcKlk4c bL5hT+wia1sP9NkULRauJtwFzGD4uMgwUl++HR9pJXA5eYTaNj/b3GHkOxED9/kCxC hrjkJp+N3W11TY8Lf4VJKbZSqHhqZRWro6kL0QIY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Krzysztof Piotr Oledzki , Heiner Kallweit , Wolfram Sang , Sasha Levin Subject: [PATCH 6.6 332/386] i2c: core: Lock address during client device instantiation Date: Tue, 8 Oct 2024 14:09:37 +0200 Message-ID: <20241008115642.448931636@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115629.309157387@linuxfoundation.org> References: <20241008115629.309157387@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiner Kallweit [ Upstream commit 8d3cefaf659265aa82b0373a563fdb9d16a2b947 ] 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: Sasha Levin --- drivers/i2c/i2c-core-base.c | 28 ++++++++++++++++++++++++++++ include/linux/i2c.h | 3 +++ 2 files changed, 31 insertions(+) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 9d918a7dfddae..943f0021d6a2c 100644 --- 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 struct resource *resources, 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 *adap, struct i2c_board_info const *inf 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 *adap, struct i2c_board_info const *inf 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 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf 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); diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 033de64d09bba..a3166100f0cce 100644 --- 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) -- 2.43.0