linux-kernel - Re: [PATCH] PCI/DPC: Extend DPC recovery timeout

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: <9d53f097-7e12-4a4c-a2e9-e7b3f2f911a9@gmail.com>
Date: Thu, 7 Aug 2025 09:54:51 +0800
From: Ethan Zhao <etzhao1900@...il.com>
To: Keith Busch <kbusch@...nel.org>, Bjorn Helgaas <helgaas@...nel.org>
Cc: Lukas Wunner <lukas@...ner.de>, Hongbo Yao <andy.xu@...micro.com>,
 Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@...ux.intel.com>,
 bhelgaas@...gle.com, mahesh@...ux.ibm.com, oohall@...il.com,
 linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
 jemma.zhang@...micro.com, peter.du@...micro.com
Subject: Re: [PATCH] PCI/DPC: Extend DPC recovery timeout



On 8/7/2025 5:52 AM, Keith Busch wrote:
> On Wed, Aug 06, 2025 at 04:34:09PM -0500, Bjorn Helgaas wrote:
>>>> However, the current 4 seconds timeout in pci_dpc_recovered() is indeed
>>>> an empirical value rather than a hard requirement from the PCIe
>>>> specification. In real-world scenarios, like with Mellanox ConnectX-5/7
>>>> adapters, we've observed that full DPC recovery can take more than 5-6
>>>> seconds, which leads to premature hotplug processing and device removal.
>>>
>>> I think Sathya's point was:  Have you made an effort to talk to the
>>> vendor and ask them to root-cause and fix the issue e.g. with a firmware
>>> update.
>>
>> Would definitely be great, but unless we have a number in the spec to
>> point to, they might just shrug and ask what the requirement is.
> 
> I agree, and I have similar problems with other arbitrary kernel timing
> decicsions. Specifically RRL where there's no spec defined number yet my
> patch to modify it has not received much consideration.
> 
>    https://lore.kernel.org/linux-pci/20250218165444.2406119-1-kbusch@meta.com/
> 
At least, with this patch, have a workaround in hand to make some device 
work.

Thanks,
Ethan