netdev - Re: [PATCH net-next v3 08/19] net: ravb: Move the IRQs get and request in the probe function

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]

Date: Mon, 8 Jan 2024 10:58:41 +0200
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Sergey Shtylyov <s.shtylyov@....ru>, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 richardcochran@...il.com, p.zabel@...gutronix.de,
 yoshihiro.shimoda.uh@...esas.com, wsa+renesas@...g-engineering.com
Cc: netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
 linux-kernel@...r.kernel.org, geert+renesas@...der.be,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH net-next v3 08/19] net: ravb: Move the IRQs get and
 request in the probe function



On 07.01.2024 20:24, Sergey Shtylyov wrote:
> On 1/5/24 11:23 AM, Claudiu wrote:
> 
>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>
>> The runtime PM implementation will disable clocks at the end of
>> ravb_probe(). As some IP variants switch to reset mode as a result of
>> setting module standby through clock disable APIs, to implement runtime PM
>> the resource parsing and requesting are moved in the probe function and IP
>> settings are moved in the open function. This is done because at the end of
>> the probe some IP variants will switch anyway to reset mode and the
>> registers content is lost. Also keeping only register specific operations
>> in the ravb_open()/ravb_close() functions will make them faster.
>>
>> Commit moves IRQ requests to ravb_probe() to have all the IRQs ready when
>> the interface is open. As now IRQs gets and requests are in a single place
>> there is no need to keep intermediary data (like ravb_rx_irqs[] and
>> ravb_tx_irqs[] arrays or IRQs in struct ravb_private).
> 
>    There's one thing that you probably didn't take into account: after
> you call request_irq(), you should be able to handle your IRQ as it's
> automatically unmasked, unless you pass IRQF_NO_AUTOEN to request_irq().
> Your device may be held i reset or even powered off but if you pass IRQF_SHARED to request_irq() (you do in a single IRQ config), you must
> be prepared to get your device's registers read (in order to ascertain
> whether it's your IRQ or not). And you can't even pass IRQF_NO_AUTOEN
> along with IRQF_SHARED, according to my reading of the IRQ code...

Good point!

> 
>> This is a preparatory change to add runtime PM support for all IP variants.
> 
>   I don't readily see why this is necessary for the full-fledged RPM
> support...

I tried to speed up the ravb_open()/ravb_close() but missed the IRQF_SHARED
IRQ. As there is only one IRQ requested w/ IRQF_SHARED, are you OK with
still keeping the rest of IRQs handled as proposed by this patch?

> 
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
>    Unfortunately, I have to NAK this patch, at least in its current
> form...
> 
> [...]
> 
> MBR, Sergey