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Date:   Sun, 2 Apr 2023 19:25:27 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Hans Petter Selasky <hps@selasky.org>
Cc:     bugzilla-daemon@kernel.org, linux-usb@vger.kernel.org
Subject: Re: [Bug 217242] CPU hard lockup related to xhci/dma
Message-ID: <2023040210-armband-spiffy-b5a5@gregkh>
References: <bug-217242-208809@https.bugzilla.kernel.org/>
 <bug-217242-208809-LGiVP9fz4d@https.bugzilla.kernel.org/>
 <7dc47823-01a1-ac19-73d4-4bf7eb07f98d@selasky.org>
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On Sun, Apr 02, 2023 at 05:54:18PM +0200, Hans Petter Selasky wrote:
> While that being said, I wish the Linux USB core would take the example of
> the FreeBSD USB core, and pre-allocate all memory needed for USB transfers,
> also called URB's, during device attach.

Many drivers do that today already, which specific ones do you think
need to have this added that are not doing so?

> Frequently going through allocate
> and free cycles during operation, is not just inefficient, but also greatly
> degrades the ability to debug the system.

Based on the slow USB speeds, "inefficient" isn't anything that I've
been able to measure specifically, have you?

> USB is still quite essential when doing remote server access. Yeah,
> the serial port is great too, but one day inb() and outb() will die

That's what a USB debugging cable is for :)

thanks,

greg k-h