linux-kernel - Re: [PATCH v3] extcon: Fixed sysfs duplicate filename issue

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Message-Id: <DF9SRIU7GHOX.1G7OOKX72555M@cknow-tech.com>
Date: Sun, 28 Dec 2025 12:01:54 +0100
From: "Diederik de Haas" <diederik@...ow-tech.com>
To: "Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>, "Diederik de
 Haas" <diederik@...ow-tech.com>
Cc: "Michael Wu" <michael@...winnertech.com>, <myungjoo.ham@...sung.com>,
 <cw00.choi@...sung.com>, <linux-kernel@...r.kernel.org>, "Dragan Simic"
 <dsimic@...jaro.org>, <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v3] extcon: Fixed sysfs duplicate filename issue

On Sat Dec 27, 2025 at 4:08 PM CET, Andy Shevchenko wrote:
> On Sun, Dec 21, 2025 at 03:01:11PM +0100, Diederik de Haas wrote:
>> On Fri Oct 24, 2025 at 4:49 AM CEST, Michael Wu wrote:
>> > With current extcon_dev_unregister() timing, ida_free is before
>> > device_unregister(), that may cause current id re-alloc to another
>> > device in extcon_dev_register() context but sysfs filename path not
>> > removal completed yet.
>> 
>> I periodically get errors like this:
>> 
>> [    7.116152] rockchip-usb2phy fe8a0000.usb2phy: error -EEXIST: failed to register extcon device
>> [    7.117005] rockchip-usb2phy fe8a0000.usb2phy: probe with driver rockchip-usb2phy failed with error -17
>> 
>> This was today on a NanoPi R5S (rk3568), but I have seen it before and
>> on multiple devices. They are all Rockchip based, but that's (quite)
>> possible because that's what I use the most (and where I pay quite a bit
>> of attention to dmesg).
>> 
>> Slightly fuller dmesg output of the above error is here:
>> https://paste.sr.ht/~diederik/42c6b3405386c823cd9f837d73a9a32e810361be
>> And via 'journalctl' I hopefully got the full dmesg output:
>> https://paste.sr.ht/~diederik/7a6109115b1ad85290de482db091dad3759ec159
>> 
>> Here are 2 similar logs, this time on PineTab2 and Quartz64-A (both rk3566)
>> https://paste.sr.ht/~diederik/cfe606801d3dab0267bea7049687d24c0d6e8d71
>> 
>> Those are all the logs I have saved, but it has happened several times
>> besides that. But most times I just rebooted and didn't save the log.
>> Today I looked a bit further, found commit 7bba9e81a6fb, searched on
>> lore.k.o and found this patch.
>> 
>> So I'm wondering whether this patch would also fix 'my' issue?
>> Or is this a different issue?
>
> But have you had a chance to test it? The code looks correct after this patch
> as the first we remove the struct device and all associated data (including
> sysfs nodes) and then remove the ID from the list. Without that there is a
> window to get the same id for the devices that is pending to be removed.

I've build a kernel with it and it will be part of my kernels going
forward. But it can take many months before the issue shows up again.
So if I don't get it in a year, then I'm going to *assume* it's probably
fixed.