From: Benno Lossin <benno.lossin@proton.me>
To: Andrew Lunn <andrew@lunn.ch>
Cc: FUJITA Tomonori <fujita.tomonori@gmail.com>,
boqun.feng@gmail.com, tmgross@umich.edu, netdev@vger.kernel.org,
rust-for-linux@vger.kernel.org, miguel.ojeda.sandonis@gmail.com,
greg@kroah.com
Subject: Re: [PATCH net-next v3 1/3] rust: core abstractions for network PHY drivers
Date: Sat, 14 Oct 2023 22:18:58 +0000 [thread overview]
Message-ID: <c807ef34-3926-4284-ab18-b516c8af57c7@proton.me> (raw)
In-Reply-To: <72a268b1-aabc-4d98-aba4-4d92c3f3dd21@lunn.ch>
On 14.10.23 23:55, Andrew Lunn wrote:
>>> The PHY driver asks the state from the abstractions then the
>>> abstractions ask the state from PHYLIB. So when the abstractions get a
>>> bad value from PHYLIB, the abstractions must return something to the
>>> PHY driver. As I wrote, the abstractions return a random value or an
>>> error. In either way, probably the system cannot continue.
>>
>> Sure then let the system BUG if it cannot continue. I think that
>> allowing UB is worse than BUGing.
>
> There is nothing a PHY driver can do which justifies calling BUG().
I was mostly replying to Tomonori's comment "In either way, probably
the system cannot continue.". I think that defaulting the value to
`PHY_ERROR` when it is out of range to be a lot better way of handling
this.
> BUG() indicates the system is totally messed up, and running further
> is going to result in more file system corruption, causing more data
> loss, so we need to stop the machine immediately.
>
> Anyway, we are talking about this bit of code in the C driver:
>
> /* Reset PHY, otherwise MII_LPA will provide outdated information.
> * This issue is reproducible only with some link partner PHYs
> */
> if (phydev->state == PHY_NOLINK) {
> phy_init_hw(phydev);
> _phy_start_aneg(phydev);
> }
>
I think that we are talking about `Device::state` i.e. the
Rust wrapper function of `phydev->state`.
> and what we should do if phydev->state is not one of the values
> defined in enum phy_state, but is actually 42. The system will
> continue, but it could be that the hardware reports the wrong value
> for LPA, the Link Partner Advertisement. That is not critical
> information, the link is likely to work, but the debug tool ethtool(1)
> will report the wrong value.
>
> Can we turn this UB into DB? I guess you can make the abstraction
> accept any value, validate it against the values in enum phy_state, do
> a WARN_ON_ONCE() if its not valid so we get a stack trace, and pass
> the value on. Life will likely continue, hopefully somebody will
> report the stack trace, and we can try to figure out what went wrong.
Then we are on the same page, as that would be my preferred solution.
--
Cheers,
Benno
next prev parent reply other threads:[~2023-10-14 22:19 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-09 1:39 [PATCH net-next v3 0/3] Rust abstractions for network PHY drivers FUJITA Tomonori
2023-10-09 1:39 ` [PATCH net-next v3 1/3] rust: core " FUJITA Tomonori
2023-10-09 3:17 ` Trevor Gross
2023-10-09 12:19 ` Benno Lossin
2023-10-09 13:02 ` Andrew Lunn
2023-10-09 13:56 ` Benno Lossin
2023-10-09 14:13 ` Andrew Lunn
2023-10-11 14:16 ` FUJITA Tomonori
2023-10-09 12:59 ` Miguel Ojeda
2023-10-09 13:49 ` FUJITA Tomonori
2023-10-09 14:32 ` Miguel Ojeda
2023-10-09 15:15 ` FUJITA Tomonori
2023-10-09 15:19 ` Miguel Ojeda
2023-10-09 15:11 ` Greg KH
2023-10-09 15:24 ` FUJITA Tomonori
2023-10-09 15:39 ` Miguel Ojeda
2023-10-09 15:50 ` FUJITA Tomonori
2023-10-11 9:59 ` Miguel Ojeda
2023-10-11 23:18 ` FUJITA Tomonori
2023-10-13 11:59 ` Miguel Ojeda
2023-10-13 15:15 ` FUJITA Tomonori
2023-10-13 18:33 ` Miguel Ojeda
2023-10-14 12:31 ` FUJITA Tomonori
2023-10-14 16:19 ` Miguel Ojeda
2023-10-12 0:29 ` FUJITA Tomonori
2023-10-09 21:07 ` Trevor Gross
2023-10-09 21:21 ` Andrew Lunn
2023-10-11 7:04 ` FUJITA Tomonori
2023-10-09 13:54 ` Andrew Lunn
2023-10-09 14:48 ` Miguel Ojeda
2023-10-09 17:04 ` Andrew Lunn
2023-10-12 3:59 ` FUJITA Tomonori
2023-10-12 4:43 ` Trevor Gross
2023-10-12 7:09 ` FUJITA Tomonori
2023-10-11 18:29 ` Boqun Feng
2023-10-12 5:58 ` FUJITA Tomonori
2023-10-12 6:34 ` Boqun Feng
2023-10-12 6:44 ` FUJITA Tomonori
2023-10-12 7:02 ` FUJITA Tomonori
2023-10-12 7:13 ` Boqun Feng
2023-10-12 7:32 ` Trevor Gross
2023-10-12 7:58 ` FUJITA Tomonori
2023-10-12 9:10 ` Benno Lossin
2023-10-13 4:17 ` Boqun Feng
2023-10-13 5:45 ` FUJITA Tomonori
2023-10-13 7:56 ` Benno Lossin
2023-10-13 9:53 ` FUJITA Tomonori
2023-10-13 10:03 ` Benno Lossin
2023-10-13 10:53 ` FUJITA Tomonori
2023-10-14 7:47 ` Benno Lossin
2023-10-14 21:55 ` Andrew Lunn
2023-10-14 22:18 ` Benno Lossin [this message]
2023-10-14 22:33 ` Andrew Lunn
2023-10-14 4:11 ` Boqun Feng
2023-10-14 11:59 ` Miguel Ojeda
2023-10-12 7:07 ` Boqun Feng
2023-10-09 1:39 ` [PATCH net-next v3 2/3] MAINTAINERS: add Rust PHY abstractions to the ETHERNET PHY LIBRARY FUJITA Tomonori
2023-10-09 1:39 ` [PATCH net-next v3 3/3] net: phy: add Rust Asix PHY driver FUJITA Tomonori
2023-10-09 3:22 ` Trevor Gross
2023-10-09 7:23 ` Jiri Pirko
2023-10-09 10:58 ` Miguel Ojeda
2023-10-09 11:41 ` FUJITA Tomonori
2023-10-09 12:32 ` Andrew Lunn
2023-10-09 14:01 ` Miguel Ojeda
2023-10-09 14:31 ` Andrew Lunn
2023-10-09 15:27 ` Miguel Ojeda
2023-10-09 15:35 ` Miguel Ojeda
2023-10-09 16:09 ` Andrew Lunn
2023-10-09 10:10 ` Greg KH
2023-10-12 11:57 ` FUJITA Tomonori
2023-10-09 12:42 ` Benno Lossin
2023-10-09 13:15 ` Andrew Lunn
2023-10-09 13:45 ` Benno Lossin
2023-10-09 12:48 ` [PATCH net-next v3 0/3] Rust abstractions for network PHY drivers Andrew Lunn
2023-10-09 12:53 ` Miguel Ojeda
2023-10-09 13:06 ` Greg KH
2023-10-09 14:13 ` Miguel Ojeda
2023-10-09 14:52 ` Greg KH
2023-10-09 15:06 ` Miguel Ojeda
2023-10-09 15:14 ` Greg KH
2023-10-09 15:15 ` Miguel Ojeda
2023-10-09 13:24 ` Andrew Lunn
2023-10-09 13:36 ` Miguel Ojeda
2023-10-09 14:21 ` Andrea Righi
2023-10-09 14:22 ` Miguel Ojeda
2023-10-09 14:56 ` Andrew Lunn
2023-10-09 15:04 ` Greg KH
2023-10-09 15:10 ` Miguel Ojeda
2023-10-09 15:15 ` Miguel Ojeda
2023-10-09 14:56 ` Greg KH
2023-10-09 15:09 ` Andrea Righi
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