linux-kernel - Re: [PATCH] usb: gadget LLVMLinux: Removing the use of VLAIS from the gadget driver

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Message-ID: <CA+55aFy6h1c3_rP_bXFedsTXzwW+9Q9MfJaW7GUmMBrAp-fJ9A@mail.gmail.com>
Date:	Mon, 23 Sep 2013 13:08:50 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Felipe Balbi <balbi@...com>
Cc:	Behan Webster <behanw@...verseincode.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	USB list <linux-usb@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Mark Charlebois <charlebm@...il.com>
Subject: Re: [PATCH] usb: gadget LLVMLinux: Removing the use of VLAIS from the
 gadget driver

On Mon, Sep 23, 2013 at 12:30 PM, Felipe Balbi <balbi@...com> wrote:
>
> I remember there was a discussion of not dropping variable length array
> support, wasn't there ?

We should definitely drop it. The feature is an abomination. I thought
gcc only allowed them at the end of structs, in the middle of a struct
it's just f*cking insane beyond belief.

That said, for *this* particular case, that USB widget driver already
does a ton of small kmalloc's and then remembers the addresses
independently. People may not care about performance, but it *might*
be a good idea to just do one kmalloc()/kfree(), and then still have
those pointer variables, but just be offsets within that one
allocation.

That's what gcc has to basically do for that thing internally
*anyway*, just hidden behind a horrible construct that should never
have existed.

              Linus
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