From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jeff Epler <jepler@unpythonic.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
"open list:PCI SUBSYSTEM" <linux-pci@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: incompatible pci sysfs change since 3.12 (5136b2da770d)
Date: Wed, 29 Oct 2014 17:36:57 -0700 [thread overview]
Message-ID: <20141030003657.GA5487@kroah.com> (raw)
In-Reply-To: <20141030002258.GA59253@unpythonic.net>
On Wed, Oct 29, 2014 at 07:22:58PM -0500, Jeff Epler wrote:
> Hi.
>
> I am an author of LinuxCNC, a GPL'd CNC control for Linux.
>
> Recently we added support for userspace PCI drivers. This worked with
> kernel 3.2 but doesn't with kernel 3.16. The software fails early with
> Failed to open "/sys/devices/pci0000:00/.../enable" (Permission denied)
>
> This appears to be because our software relies on the documented
> "enable" sysfs file for pci devices (Documentation/filesystem/sysfs-pci.txt)
> which was (unintentionally?) changed to "enabled" in the above-named
> patch:
>
> 5136b2da770d PCI: convert bus code to use dev_groups
> ...
> +static DEVICE_ATTR_RW(enabled);
> ...
> - __ATTR(enable, 0600, is_enabled_show, is_enabled_store),
>
> Are we in the LinuxCNC project wrong in thinking that stuff in /sys (and
> not /sys/debug) is supposed to be a durable API/interface for userspace
> to the kernel? (It must be a low-usage API if it went unnoticed for a
> year :-/)
Ugh, that's my fault, I made a typo and should not have renamed the
sysfs file, very sorry about that.
I'll work on making up a patch to fix this and get it into the stable
kernels so that you don't have to have a work-around for very long.
> We'll have to work around it by modifying our software (since we'd like
> to work with the kernels people already have) in any case.
>
> Even if it is not going to be changed compatibly with older kernels, it
> seems like the documentation should be updated!
I'll fix it up, this was just a bug, my apologies.
greg k-h
next prev parent reply other threads:[~2014-10-30 0:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-30 0:22 incompatible pci sysfs change since 3.12 (5136b2da770d) Jeff Epler
2014-10-30 0:36 ` Greg Kroah-Hartman [this message]
2014-10-30 1:16 ` Jeff Epler
2014-10-30 16:30 ` Greg Kroah-Hartman
2014-10-30 18:09 ` Jeff Epler
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