From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from na3sys010aog111.obsmtp.com ([74.125.245.90]:52888 "HELO na3sys010aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753540AbaHLWaX convert rfc822-to-8bit (ORCPT ); Tue, 12 Aug 2014 18:30:23 -0400 Received: by mail-pa0-f47.google.com with SMTP id kx10so13787184pab.34 for ; Tue, 12 Aug 2014 15:30:22 -0700 (PDT) Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: [PATCH] PCI: pciehp: Use ordered workqueue for HPC events From: Sandeep S Mann In-Reply-To: <20140812213626.GA6333@google.com> Date: Tue, 12 Aug 2014 15:30:21 -0700 Cc: linux-pci@vger.kernel.org, Rajat Jain Message-Id: <361417F9-AEA8-4C83-BD04-D5DD8CD4A391@purestorage.com> References: <1406933232-1560-1-git-send-email-sandeep@purestorage.com> <20140812213626.GA6333@google.com> To: Bjorn Helgaas Sender: linux-pci-owner@vger.kernel.org List-ID: > Did you find this by code inspection, or did you actually observe a > problem? If the latter, what were the symptoms? > > shpchp does the same thing, so I assume it requires the same fix. Hi Bjorn, This issue was observed on a system, where I was experimenting with pcie hot-plug and the device being hot plugged is not the most well behaved. It exhibits the following behavior: - Initialization of the device can take “relatively” long (order 100s ms) - On hot add the link presence can toggle before stabilizing The toggle of device presence can generate multiple events on a single hot plug, where one hot add event can lead to following events ADD->REMOVE->ADD. And given the device can take some time to initialize, we can have three HP events being processed concurrently. Also note this seen with surprise ADD and REMOVE. S