linux-kernel - Re: [PATCH 1/1] tty: serial: handle HAS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <e855900a-28d2-424b-8b3e-63c3c10c2848@app.fastmail.com>
Date: Fri, 06 Dec 2024 17:02:04 +0100
From: "Arnd Bergmann" <arnd@...nel.org>
To: "Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>
Cc: "Guenter Roeck" <linux@...ck-us.net>,
 "Niklas Schnelle" <schnelle@...ux.ibm.com>,
 "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
 "Jiri Slaby" <jirislaby@...nel.org>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 linux-serial@...r.kernel.org, "Heiko Carstens" <hca@...ux.ibm.com>,
 linux-kernel@...r.kernel.org, "Yang Yingliang" <yangyingliang@...wei.com>
Subject: Re: [PATCH 1/1] tty: serial: handle HAS_IOPORT dependencies

On Fri, Dec 6, 2024, at 16:44, Andy Shevchenko wrote:
> On Wed, Dec 04, 2024 at 11:17:56PM +0100, Arnd Bergmann wrote:
>> On Wed, Dec 4, 2024, at 22:09, Guenter Roeck wrote:
>
>> I got stuck in this rabbit hole of running into more issues
>> with the 8250 driver. Any time you touch something, it breaks
>> elsewhere.
>> 
>> I've uploaded what I have here now:
>
> FWIW, I have briefly looked at it, some patches I appreciate very much, some of
> them I think need more testing and one thing I don't really like is putting
> code back to 8250_core. Thinking about that, perhaps we need to restore 8250.c
> (or alike) for collecting non-library / non-_particular_-driver-leaf?

Thanks for taking a look!

I thought you might have different ideas on where some of the
code needs to go,  as you were the one who moved it out
previously.

However, I think the two bits that I ended up moving back
really belong in the core:

- serial8250_setup_ports() is needed to get the
  serial8250_ports[] into a sane state. Ideally this
  array would just be statically initialized, but I don't
  think we can actually express that in C code.

- serial8250_init()/serial8250_exit() are required for
  registering the driver itself (serial8250_reg) Having
  that part in the ISA driver made no sense to me.

The bit that is definitely ugly is how serial8250_isa_init()
gets called from serial8250_init() and univ8250_console_init(),
and I would prefer to remove that, but any attempt to do
that made it worse.

The problem here is that we can't just rely on link order:
For the console initcall and  serial8250_isa_init_ports(),
we have to call this before the core driver initialization,
but the serial8250-isa platform device has to be registered
after the core driver does. If we link both files into
a loadable module, there is an additional problem of
not being able to have more than one module_init() call.

      Arnd