linux-kernel - Re: [PATCH v5 1/3] dt-bindings: mailbox: add google,gs101-mbox

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

Message-ID: <4e97b33f-b4a5-4875-a65d-9e25bcc5a46c@linaro.org>
Date: Fri, 3 Jan 2025 09:57:34 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Jassi Brar <jassisinghbrar@...il.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>,
 Alim Akhtar <alim.akhtar@...sung.com>, linux-kernel@...r.kernel.org,
 linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, andre.draszik@...aro.org,
 peter.griffin@...aro.org, kernel-team@...roid.com, willmcvicker@...gle.com,
 daniel.lezcano@...aro.org, vincent.guittot@...aro.org,
 ulf.hansson@...aro.org, arnd@...db.de
Subject: Re: [PATCH v5 1/3] dt-bindings: mailbox: add google,gs101-mbox

Hi, Jassi,

On 1/3/25 3:39 AM, Jassi Brar wrote:
>>> Looking at v6, I prefer this version... maybe modify it a bit.
>>
>> Just to summarize for the readers, in the end I chose for the
>> controllers to allow #mbox-cells = <0>; and for the clients to still use
>> the mboxes property, but just to reference the phandle to the controller:
>>         mboxes = <&ap2apm_mailbox>;
>>
> This was already supported, see drivers/mailbox/bcm2835-mailbox.c for example.

Thanks for the pointer. I was referring to the bindings patch:
https://lore.kernel.org/linux-arm-kernel/20241220-acpm-v4-upstream-mbox-v6-1-a6942806e52a@linaro.org/
> 
>> Then I updated the mailbox core to allow clients to request channels by
>> passing some args containing channel identifiers to the controllers,
>> that the controllers xlate() using their own method.
>>
> This is unnecessary.
> If you don't pass the doorbell number from DT, each channel populated
> by the driver is just a s/w construct or a 'virtual' channel. Make use
> of 'void *data'  in send_data() to specify the doorbell.
> 

I think this introduces concurrency problems if the channel identifiers
passed by 'void *data' don't match the virtual channel used for sending
the messages. Do we want to allow this?

Also, if we use 'void *data' to pass channel identifiers, the channel
checks will have to be made at send_data() time. Thus if passing wrong
channel type for example, the mailbox client will eventually get a
-ENOBUFS and a "Try increasing MBOX_TX_QUEUE_LEN" message, which I find
misleading.

Thanks,
ta