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

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Message-ID: <aVFoNbsd13ufl7ge@smile.fi.intel.com>
Date: Sun, 28 Dec 2025 19:26:13 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: 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 Sun, Dec 28, 2025 at 12:01:54PM +0100, Diederik de Haas wrote:
> 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.

I believe you may speed up the test case by creating two shell scripts that
trying insmod / rmmod the same module in parallel.

-- 
With Best Regards,
Andy Shevchenko