From patchwork Wed Feb 28 02:39:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hamish Martin X-Patchwork-Id: 13574814 Received: from gate2.alliedtelesis.co.nz (gate2.alliedtelesis.co.nz [202.36.163.20]) (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 CE4A71CD0F for ; Wed, 28 Feb 2024 02:39:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.36.163.20 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709087985; cv=none; b=Ho9WC0j1f3INVG2qvaOrokW2WkHTm5+QKF3CEVXHqDAJyHcltZZYKl1+d4VgQvthbPwFXEbcUUR4bFebzdPIT2JwCULgOmlOt6p34lR5i/h+JXRDA/SmxsutEzUDi0wiJnknyZ+mhax8oSe+jJUfFnDO6VBpcdAA635+p7oHmWg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709087985; c=relaxed/simple; bh=DYKsPK+nAJRHdem3y+JromxDS/bOMz+5yFpxfUA6UcY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Y+UVj7TUaIcEKZBnGCT3zQJ8JspYtYVUAFQv7dyz/S3GaQm+9Wpf4DMxVDds70UP9RcMlj4FCYjY5Ni55Zjgq6hWBzTrrPX7ceu/c1h/1t1T0JGCqqDVBRNuFwk9HFmpRys62+jEUCR786MpqwHBmbysUp5W9scfj05oZ0mg1yI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=alliedtelesis.co.nz; spf=pass smtp.mailfrom=alliedtelesis.co.nz; dkim=pass (2048-bit key) header.d=alliedtelesis.co.nz header.i=@alliedtelesis.co.nz header.b=UXSuuIK9; arc=none smtp.client-ip=202.36.163.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=alliedtelesis.co.nz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alliedtelesis.co.nz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=alliedtelesis.co.nz header.i=@alliedtelesis.co.nz header.b="UXSuuIK9" Received: from svr-chch-seg1.atlnz.lc (mmarshal3.atlnz.lc [10.32.18.43]) (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) (Client did not present a certificate) by gate2.alliedtelesis.co.nz (Postfix) with ESMTPS id 9A60E2C0F60; Wed, 28 Feb 2024 15:39:40 +1300 (NZDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alliedtelesis.co.nz; s=mail181024; t=1709087980; bh=74NS7Xkcqh5ka9xf2XrX1XQHgALZjeqj8WkhUPSZZYM=; h=From:To:Cc:Subject:Date:From; b=UXSuuIK9goyR5rN58VCscnPrD5Gxu2sbEi8E91bvR3saSdYexpO5T4Ly3bikpM/eY j8XYiXS6irm4PFryVhI7i3V0Rv7F2hJtFEwKs8TfYJ5IQN815L2syrq68NLAzwBGo1 xiS0h1te7BnNazxVGFDaGAzFf6X0+21H78AE035fdUNWFXTRA1N7Po3UWnOIPxjjSV uZLF2vjO1RZ301DjltHrNgqF+Wre3BcfU1rVGyr15Opvt+zZwgFKKfOaxnYxY7B5ZI qmk9VFzYJJG8rb7gqgaXwfLI7MZKbIa5tzy9X9N77E+XBmsEGo/vMqrnAgXS+Z5O6r 21ooNiWJokoxQ== Received: from pat.atlnz.lc (Not Verified[10.32.16.33]) by svr-chch-seg1.atlnz.lc with Trustwave SEG (v8,2,6,11305) id ; Wed, 28 Feb 2024 15:39:40 +1300 Received: from hamishm-dl.ws.atlnz.lc (hamishm-dl.ws.atlnz.lc [10.33.24.13]) by pat.atlnz.lc (Postfix) with ESMTP id 70F7F13EDA8; Wed, 28 Feb 2024 15:39:40 +1300 (NZDT) Received: by hamishm-dl.ws.atlnz.lc (Postfix, from userid 1133) id 6D19B240BBF; Wed, 28 Feb 2024 15:39:40 +1300 (NZDT) From: Hamish Martin To: mika.westerberg@linux.intel.com, wsa+renesas@sang-engineering.com Cc: linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, Hamish Martin Subject: [PATCH 0/1] I2C mux ACPI SSDT overlay removal issue Date: Wed, 28 Feb 2024 15:39:24 +1300 Message-ID: <20240228023925.2814638-1-hamish.martin@alliedtelesis.co.nz> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SEG-SpamProfiler-Analysis: v=2.4 cv=BKkQr0QG c=1 sm=1 tr=0 ts=65de9cec a=KLBiSEs5mFS1a/PbTCJxuA==:117 a=k7vzHIieQBIA:10 a=nXG3BeEQHGMQi2UDEzgA:9 a=3ZKOabzyN94A:10 X-SEG-SpamProfiler-Score: 0 x-atlnz-ls: pat I have found an issue with ACPI overlay table removal specifically related to I2C multiplexers. Consider an ACPI SSDT Overlay such as the following which defines a PCA9548 I2C mux "MUX0" on the existing I2C bus "\_SB.I2CA": DefinitionBlock ("my_mux.asl", "SSDT", 1, "ATL", "RMUX", 0x00000001) { External (\_SB.I2CA, DeviceObj) Scope (\_SB.I2CA) { // i2c mux (8-Channel) Device (MUX0) { Name (_HID, "PRP0001") // Use compatible string Name (_CRS, ResourceTemplate () { I2cSerialBusV2 (0x70, ControllerInitiated, 100000, AddressingMode7Bit, "\\_SB.I2CA", 0x00, ResourceConsumer, , Exclusive, ) }) Name (_DSD, Package () { ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), // Device Properties UUID Package () { Package () { "name", "cex_direct_mux" }, Package () { "compatible", "nxp,pca9548" }, Package () { "i2c-mux-idle-disconnect", "" }, } }) Device (CH00) { name (_ADR, 0) } Device (CH01) { name (_ADR, 1) } Device (CH02) { name (_ADR, 2) } Device (CH03) { name (_ADR, 3) } Device (CH04) { name (_ADR, 4) } Device (CH05) { name (_ADR, 5) } Device (CH06) { name (_ADR, 6) } Device (CH07) { name (_ADR, 7) } } } } When this table is loaded (using configfs method) we see the creation of a device for the overall PCA9548 chip and 8 further devices - one i2c_adapter each for the mux channels. These are all bound to their ACPI equivalents via an eventual invocation of acpi_bind_one(). When we unload the SSDT overlay (rmdir /sys/kernel/config/acpi/table/my_mux/) we run into the problem. The ACPI devices are deleted via acpi_device_del_work_fn() and the acpi_device_del_list. The following warning and stack trace is output as the deletion does not go smoothly: # rmdir /sys/kernel/config/acpi/table/my_mux/ ------------[ cut here ]------------ kernfs: can not remove 'physical_node', no directory WARNING: CPU: 1 PID: 11 at fs/kernfs/dir.c:1674 kernfs_remove_by_name_ns+0xb9/0xc0 Modules linked in: CPU: 1 PID: 11 Comm: kworker/u128:0 Not tainted 6.8.0-rc6+ #1 Hardware name: congatec AG conga-B7E3/conga-B7E3, BIOS 5.13 05/16/2023 Workqueue: kacpi_hotplug acpi_device_del_work_fn RIP: 0010:kernfs_remove_by_name_ns+0xb9/0xc0 Code: e4 00 48 89 ef e8 07 71 db ff 5b b8 fe ff ff ff 5d 41 5c 41 5d e9 a7 55 e4 00 0f 0b eb a6 48 c7 c7 f0 38 0d 9d e8 97 0a d5 ff <0f> 0b eb dc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffff9f864008fb28 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff8ef90a8d4940 RCX: 0000000000000000 RDX: ffff8f000e267d10 RSI: ffff8f000e25c780 RDI: ffff8f000e25c780 RBP: ffff8ef9186f9870 R08: 0000000000013ffb R09: 00000000ffffbfff R10: 00000000ffffbfff R11: ffff8f000e0a0000 R12: ffff9f864008fb50 R13: ffff8ef90c93dd60 R14: ffff8ef9010d0958 R15: ffff8ef9186f98c8 FS: 0000000000000000(0000) GS:ffff8f000e240000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f48f5253a08 CR3: 00000003cb82e000 CR4: 00000000003506f0 Call Trace: ? kernfs_remove_by_name_ns+0xb9/0xc0 ? __warn+0x7c/0x130 ? kernfs_remove_by_name_ns+0xb9/0xc0 ? report_bug+0x171/0x1a0 ? handle_bug+0x3c/0x70 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? kernfs_remove_by_name_ns+0xb9/0xc0 ? kernfs_remove_by_name_ns+0xb9/0xc0 acpi_unbind_one+0x108/0x180 device_del+0x18b/0x490 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f device_unregister+0xd/0x30 i2c_del_adapter.part.0+0x1bf/0x250 i2c_mux_del_adapters+0xa1/0xe0 i2c_device_remove+0x1e/0x80 device_release_driver_internal+0x19a/0x200 bus_remove_device+0xbf/0x100 device_del+0x157/0x490 ? __pfx_device_match_fwnode+0x10/0x10 ? srso_return_thunk+0x5/0x5f device_unregister+0xd/0x30 i2c_acpi_notify+0x10f/0x140 notifier_call_chain+0x58/0xd0 blocking_notifier_call_chain+0x3a/0x60 acpi_device_del_work_fn+0x85/0x1d0 process_one_work+0x134/0x2f0 worker_thread+0x2f0/0x410 ? __pfx_worker_thread+0x10/0x10 kthread+0xe3/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 ---[ end trace 0000000000000000 ]--- ... repeated 7 more times, 1 for each channel of the mux ... The issue as I see it is that the binding of the ACPI devices to their peer I2C adapters is not correctly cleaned up. Digging deeper into the issue we see that the deletion order is such that the ACPI devices matching the mux channel i2c adapters are deleted first during the SSDT overlay removal. For each of the channels we see a call to i2c_acpi_notify() with ACPI_RECONFIG_DEVICE_REMOVE but, because these devices are not actually i2c_clients, nothing is done for them. Later on, after each of the mux channels has been dealt with, we come to delete the i2c_client representing the PCA9548 device. This is the call stack we see above, whereby the kernel cleans up the i2c_client including destruction of the mux and it's channel adapters (i2c_mux_del_adapters() -> i2c_del_adapter()). At this point we do attempt to unbind from the ACPI peers but those peers no longer exist and so we hit the kernfs errors. My proposed fix is to augment i2c_acpi_notify() to handle i2c_adapters. But, given that the life cycle of the adapters is linked to the i2c_client, instead of deleting the i2c_adapters during the i2c_acpi_notify(), we instead just trigger unbinding of the ACPI device from the adapter device, and allow the cleanup of the adapter to continue in the way it always has. This fix resolves my specific issue with the I2C mux removal. However, I'm not sure about whether there is a better fix for this issue so if you have suggestions please let me know. I'm not sure if there needs to be further code to ensure this new code only runs for this specific case where the i2c_adapters are part of an i2c mux. Guidance on this would be appreciated. Hamish Martin (1): i2c: acpi: Unbind mux adapters before delete drivers/i2c/i2c-core-acpi.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)