Message-ID: <55098a4d-c227-b9f3-63d0-6810f99d9530@deltatee.com>
Date:   Thu, 2 Mar 2017 16:11:02 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Keith Busch <keith.busch@...el.com>,
        Myron Stowe <myron.stowe@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Jonathan Corbet <corbet@....net>,
        "David S. Miller" <davem@...emloft.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Emil Velikov <emil.l.velikov@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        Wei Zhang <wzhang@...com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     Kurt Schwemmer <kurt.schwemmer@...rosemi.com>,
        Stephen Bates <stephen.bates@...rosemi.com>,
        linux-pci@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 0/4] New Microsemi PCI Switch Management Driver

Hey,

Ah, sorry, sorry. I noticed another minor mistake. I'll send a v7 in a
second.

Thanks,

Logan

On 02/03/17 04:07 PM, Logan Gunthorpe wrote:
> Hi,
> 
> Hopefully this is the last change necessary. The new code to handle
> unbind follows Jason's suggestions and is a lot easier to reason about.
> It's also been tested interrupting a number of operations.
> 
> Thanks,
> 
> Logan
> 
> --
> 
> Changes since v5:
> 
> * Reworked cleanup during unbind again. This time we follow the pattern
>   roughly suggested by Jason Gunthorpe: we use an alive flag
>   that's checked with a rw semaphore held by the cdev ops. Except
>   instead of using the rwsem we just use the already existing
>   mrpc_mutex. (Seeing the vast majority of locations that would use the
>   semaphore overlap with the existing mutex.)
> * Added a small performance enhancement so the code reads less io memory
>   if the user is quick in submitting their read request.
> 
> Changes since v4:
> 
> * Turns out pushing the pci release code into the device release
>   function didn't work as I would have liked. If you try to unbind the
>   device with an instance open, then you hit a kernel bug at
>   drivers/pci/msi.c:371. (This didn't occur in v3.)
> 
>   To solve this, we've moved the pci release code back into the
>   unregister function and reintroduced an alive flag. This time,
>   however, the alive flag is protected by mrpc_mutex and we're very
>   careful about what happens to devices still in use (they should
>   all be released through the timeout path and an ENODEV error
>   returned to userspace; while new commands are blocked with the
>   same error).
> 
> Changes since v3:
> 
> * Removed stdev_is_alive and moved pci deinit functions
>   into the device release function which only occurs after all
>   cdev instances are closed. (per Bjorn)
> * Reduced locking in read/write functions (per Bjorn)
> * Use pci_alloc_irq_vectors to vastly improve ISR initialization (Bjorn)
> * A few other minor nits and cleanup as noticed by Bjorn
> 
> Changes since v2:
> 
> * Collected reviewed and tested tags
> * Very minor fix to the error path in the create function
> 
> Changes since v1:
> 
> * Rebased onto 4.10-rc6 (cleanly)
> * Split the patch into a few more easily digestible patches (as
>   suggested by Greg Kroah-Hartman)
> * Folded switchtec.c into switchtec.h (per Greg)
> * Fixed a bunch of 32bit build warnings caught by the kbuild test robot
> * Fixed some issues in the documentation so it has a proper
>   reStructredText format (as noted by Jonathan Corbet)
> * Fixed padding and sizes in the IOCTL structures as noticed by Emil
>   Velikov and used pahole to verify their consistency across 32 and 64
>   bit builds
> * Reworked one of the IOCTL interfaces to be more future proof (per
>   Emil).
> 
> Changes since RFC:
> 
> * Fixed incorrect use of the drive model as pointed out by Greg
>   Kroah-Hartman
> * Used devm functions as suggested by Keith Busch
> * Added a handful of sysfs attributes to the switchtec class
> * Added a handful of IOCTLs to the switchtec device
> * A number of miscellaneous bug fixes
> 
> --
> 
> Hi,
> 
> This is a continuation of the RFC we posted lasted month [1] which
> proposes a management driver for Microsemi's Switchtec line of PCI
> switches. This hardware is still looking to be used in the Open
> Compute Platform
> 
> To make this entirely clear: the Switchtec products are compliant
> with the PCI specifications and are supported today with the standard
> in-kernel driver. However, these devices also expose a management endpoint
> on a separate PCI function address which can be used to perform some
> advanced operations. This is a driver for that function. See the patch
> for more information.
> 
> Since the RFC, we've made the changes requested by Greg Kroah-Hartman
> and Keith Busch, and we've also fleshed out a number of features. We've
> added a couple of IOCTLs and sysfs attributes which are documented in
> the patch. Significant work has also been done on the userspace tool
> which is available under a GPL license at [2]. We've also had testing
> done by some of the interested parties.
> 
> We hope to see this work included in either 4.11 or 4.12 assuming a
> smooth review process.
> 
> The patch is based off of the v4.10-rc6 release.
> 
> Thanks for your review,
> 
> Logan
> 
> [1] https://www.spinics.net/lists/linux-pci/msg56897.html
> [2] https://github.com/sbates130272/switchtec-user
> 
> Logan Gunthorpe (4):
>   MicroSemi Switchtec management interface driver
>   switchtec: Add user interface documentation
>   switchtec: Add sysfs attributes to the Switchtec driver
>   switchtec: Add IOCTLs to the Switchtec driver
> 
>  Documentation/ABI/testing/sysfs-class-switchtec |   96 ++
>  Documentation/ioctl/ioctl-number.txt            |    1 +
>  Documentation/switchtec.txt                     |   80 ++
>  MAINTAINERS                                     |   11 +
>  drivers/pci/Kconfig                             |    1 +
>  drivers/pci/Makefile                            |    1 +
>  drivers/pci/switch/Kconfig                      |   13 +
>  drivers/pci/switch/Makefile                     |    1 +
>  drivers/pci/switch/switchtec.c                  | 1599 +++++++++++++++++++++++
>  include/uapi/linux/switchtec_ioctl.h            |  132 ++
>  10 files changed, 1935 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-switchtec
>  create mode 100644 Documentation/switchtec.txt
>  create mode 100644 drivers/pci/switch/Kconfig
>  create mode 100644 drivers/pci/switch/Makefile
>  create mode 100644 drivers/pci/switch/switchtec.c
>  create mode 100644 include/uapi/linux/switchtec_ioctl.h
> 
> --
> 2.1.4
> 

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