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ec35c19696
The network device outlived its parent gadget device during
disconnection, resulting in dangling sysfs links and null pointer
dereference problems.
A prior attempt to solve this by removing SET_NETDEV_DEV entirely [1]
was reverted due to power management ordering concerns and a NO-CARRIER
regression.
A subsequent attempt to defer net_device allocation to bind [2] broke
1:1 mapping between function instance and network device, making it
impossible for configfs to report the resolved interface name. This
results in a regression where the DHCP server fails on pmOS.
Use device_move to reparent the net_device between the gadget device and
/sys/devices/virtual/ across bind/unbind cycles. This preserves the
network interface across USB reconnection, allowing the DHCP server to
retain their binding.
Introduce gether_attach_gadget()/gether_detach_gadget() helpers and use
__free(detach_gadget) macro to undo attachment on bind failure. The
bind_count ensures device_move executes only on the first bind.
[1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/
[2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/
Fixes: 40d133d7f5 ("usb: gadget: f_ncm: convert to new function interface with backward compatibility")
Cc: stable <stable@kernel.org>
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20260309-f-ncm-revert-v2-7-ea2afbc7d9b2@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
39 lines
811 B
C
39 lines
811 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* u_ncm.h
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*
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* Utility definitions for the ncm function
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*
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* Copyright (c) 2013 Samsung Electronics Co., Ltd.
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* http://www.samsung.com
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*
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* Author: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
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*/
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#ifndef U_NCM_H
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#define U_NCM_H
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#include <linux/usb/composite.h>
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struct f_ncm_opts {
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struct usb_function_instance func_inst;
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struct net_device *net;
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int bind_count;
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struct config_group *ncm_interf_group;
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struct usb_os_desc ncm_os_desc;
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char ncm_ext_compat_id[16];
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/*
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* Read/write access to configfs attributes is handled by configfs.
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*
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* This is to protect the data from concurrent access by read/write
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* and create symlink/remove symlink.
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*/
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struct mutex lock;
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int refcnt;
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u16 max_segment_size;
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};
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#endif /* U_NCM_H */
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