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: <a3c87f21-7e49-99a5-026f-4a24e0cb7a86@gmail.com>
Date:   Fri, 16 Oct 2020 16:41:50 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Mike Galbraith <efault@....de>, netdev <netdev@...r.kernel.org>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>
Subject: Re: [patchlet] r8169: fix napi_schedule_irqoff() called with irqs
 enabled warning

On 16.10.2020 16:26, Vladimir Oltean wrote:
> On Fri, Oct 16, 2020 at 01:34:55PM +0200, Heiner Kallweit wrote:
>> I'm aware of the topic, but missing the benefits of the irqoff version
>> unconditionally doesn't seem to be the best option.
> 
> What are the benefits of the irqoff version? As far as I see it, the
> only use case for that function is when the caller has _explicitly_
> disabled interrupts.
> 
If the irqoff version wouldn't have a benefit, then I think we wouldn't
have it ..

> The plain napi_schedule call will check if irqs are disabled. If they
> are, it won't do anything further in that area. There is no performance
> impact except for a check.
> 
There is no such check, and in general currently attempts are made to
remove usage of e.g. in_interrupt(). napi_schedule() has additional calls
to local_irq_save() and local_irq_restore().

>> Needed is a function that dynamically picks the right version.
> 
> So you want to replace a check with another check, am I right? How will
> that improve anything performance-wise?
> 

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ