linux-kernel - Re: [PATCH] usb: usbfs: Add reset

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Message-ID: <d3ee7c98-c987-48db-b68c-645b38ae51a2@suse.com>
Date: Mon, 25 Aug 2025 11:50:10 +0200
From: Oliver Neukum <oneukum@...e.com>
To: 自己 <ccc194101@....com>,
 Alan Stern <stern@...land.harvard.edu>
Cc: gregkh@...uxfoundation.org, jannh@...gle.com, rex.nie@...uarmicro.com,
 linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
 chenchangcheng <chenchangcheng@...inos.cn>
Subject: Re: [PATCH] usb: usbfs: Add reset_resume callback to usbfs.

On 8/25/25 04:19, 自己 wrote:

> According to the current experimental findings, when userspace encounters
> an error while using the previous file descriptor (fd), it does not proceed to unbind
> and rebind automatically. Therefore, the two uevents were added in the kernel to explicitly
> notify userspace to unbind and rebind.

Sure, but that means that user space has a bug.
That race is present in every case. Even if the kernel
were to notify user space by additional channels,
user space could already be in the process of calling
into the kernel.
There is no way of avoiding the need for user space
to handle this error return correctly.

	Regards
		Oliver