linux-kernel - Re: [PATCH] sysfs: add per pci device msi[x] irq listing (v4)

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Date:	Thu, 29 Sep 2011 07:51:26 -0700
From:	Greg KH <gregkh@...e.de>
To:	Neil Horman <nhorman@...driver.com>
Cc:	linux-kernel@...r.kernel.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org
Subject: Re: [PATCH] sysfs: add per pci device msi[x] irq listing (v4)

On Thu, Sep 29, 2011 at 10:38:49AM -0400, Neil Horman wrote:
> This patch adds a per-pci-device subdirectory in sysfs called:
> /sys/bus/pci/devices/<device>/msi_irqs
> 
> This sub-directory exports the set of msi vectors allocated by a given
> pci device, by creating a numbered sub-directory for each vector beneath
> msi_irqs.  For each vector various attributes can be exported.  Currently the
> only attribute is called mode, which tracks the operational mode of that vector
> (msi vs. msix)
> 
> ---
> 
> Change Notes:
> 
> (v2)
> Fixed up Documentation to put new sysfs interface descriptions in the right
> place, as per request by Greg K-H
> 
> Fixed up oops that resulted from removing pci device.  Not 100% sure I did this
> exactly right, but looking at the crash (triggered by echo 1 >
> /sys/class/net/eth0/device/remove), it looked as though we were freeing the
> pci_dev struct prior to all sysfs objects releasing their use of the device.  AS
> such it seemed most appropriate to hold references on the pci_dev for each msi
> irq sysfs object that we create, and release them on free accordingly.  With
> this change in place, I can remove, and add (via rescan) msi enabled devices
> ad-nauseum without a panic.  Again thanks to Greg K-H
> 
> (v3)
> As per Gregs suggestion, I looked further and noted that in fact, yes, it wasn't
> producing any errors on remove, but only because I had a refcounting problem,
> and my new sysfs objects were left orphaned with a dangling refcount.  I've
> fixed that, added a release method to the new ktype, which now drops the
> reference I hold on the pci_dev for us and I've validated that all objects I've
> created, along with the parent directory and pci device are cleaned up and freed
> by enabling the kobject dyanic_debug set and observing the appropriate release
> calls.  I can provide the logs if anyone wants to review them specifically.
> 
> (v4)
> Fixed up some spelling mistakes, and added a scissors line with a good
> commitlog, so that git-am drops all the version logging
> 
> Signed-off-by: Neil Horman <nhorman@...driver.com>
> CC: Greg Kroah-Hartman <gregkh@...e.de>

Acked-by: Greg Kroah-Hartman <gregkh@...e.de>
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