linux-kernel - Re: [PATCH v5 4/5] Driver core: platform: Add devm_platform_get_irqs

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: <36730230-9fd7-8c6c-b997-328beea2fc31@huawei.com>
Date:   Wed, 9 Dec 2020 19:04:02 +0000
From:   John Garry <john.garry@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <jejb@...ux.ibm.com>, <martin.petersen@...cle.com>,
        <lenb@...nel.org>, <rjw@...ysocki.net>, <tglx@...utronix.de>,
        <maz@...nel.org>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>,
        <linux-acpi@...r.kernel.org>, <dwagner@...e.de>
Subject: Re: [PATCH v5 4/5] Driver core: platform: Add
 devm_platform_get_irqs_affinity()

On 09/12/2020 18:32, Greg KH wrote:
> On Wed, Dec 02, 2020 at 06:36:56PM +0800, John Garry wrote:
>> Drivers for multi-queue platform devices may also want managed interrupts
>> for handling HW queue completion interrupts, so add support.
> 

Hi Greg,

> Why would a platform device want all of this?  Shouldn't such a device
> be on a "real" bus instead?

For this HW version, the device is on the system bus, directly 
addressable by the CPU.

Motivation is that I wanted to switch the HW completion queues to use 
managed interrupts.

> 
> What in-kernel driver needs this complexity?  I can't take new apis
> without a real user in the tree, sorry.

It's in the final patch in the series 
https://lore.kernel.org/linux-scsi/1606905417-183214-1-git-send-email-john.garry@huawei.com/T/#m0df7e7cd6f0819b99aaeb6b7f8939ef1e17b8a83.

I don't anticipate a huge number of users of this API in future, as most 
multi-queue devices are PCI devices; so we could do the work of this API 
in the driver itself, but the preference was not to export genirq 
functions like irq_update_affinity_desc() or 
irq_create_affinity_masks(), and rather have a common helper in the core 
platform code.

Thanks,
John