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From: Sandeep S Mann <sandeep@purestorage.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org, Rajat Jain <rajatxjain@gmail.com>
Subject: Re: [PATCH] PCI: pciehp: Use ordered workqueue for HPC events
Date: Tue, 12 Aug 2014 15:30:21 -0700	[thread overview]
Message-ID: <361417F9-AEA8-4C83-BD04-D5DD8CD4A391@purestorage.com> (raw)
In-Reply-To: <20140812213626.GA6333@google.com>


> 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



  reply	other threads:[~2014-08-12 22:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-01 22:47 [PATCH] PCI: pciehp: Use ordered workqueue for HPC events Sandeep Mann
2014-08-04 20:22 ` Rajat Jain
2014-08-12 22:00 ` Bjorn Helgaas
2014-08-12 22:30   ` Sandeep S Mann [this message]
2014-08-12 23:31     ` Rajat Jain
2014-08-13  0:09       ` Sandeep S Mann
2014-08-13  0:33         ` Rajat Jain
2014-08-13 17:00           ` Sandeep S Mann
2014-09-04 21:10 ` Bjorn Helgaas
2014-11-04  8:10   ` Rajat Jain

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