> -----Original Message----- > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > Sent: Monday, May 6, 2019 5:03 PM > To: Parav Pandit <parav@xxxxxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kwankhede@xxxxxxxxxx; cjia@xxxxxxxxxx > Subject: Re: [PATCHv2 00/10] vfio/mdev: Improve vfio/mdev core module > > On Tue, 30 Apr 2019 17:49:27 -0500 > Parav Pandit <parav@xxxxxxxxxxxx> wrote: > > > As we would like to use mdev subsystem for wider use case as discussed > > in [1], [2] apart from an offline discussion. > > This use case is also discussed with wider forum in [4] in track > > 'Lightweight NIC HW functions for container offload use cases'. > > > > This series is prep-work and improves vfio/mdev module in following ways. > > > > Patch-1 Fixes releasing parent dev reference during error unwinding > > mdev parent registration. > > Patch-2 Simplifies mdev device for unused kref. > > Patch-3 Drops redundant extern prefix of exported symbols. > > Patch-4 Returns right error code from vendor driver. > > Patch-5 Fixes to use right sysfs remove sequence. > > Patch-6 Fixes removing all child devices if one of them fails. > > Patch-7 Remove unnecessary inline > > Patch-8 Improve the mdev create/remove sequence to match Linux > > bus, device model > > Patch-9 Avoid recreating remove file on stale device to > > eliminate call trace > > Patch-10 Fix race conditions of create/remove with parent removal This > > is improved version than using srcu as srcu can take seconds to > > minutes. > > > > This series is tested using > > (a) mtty with VM using vfio_mdev driver for positive tests and device > > removal while device in use by VM using vfio_mdev driver > > > > (b) mlx5 core driver using RFC patches [3] and internal patches. > > Internal patches are large and cannot be combined with this prep-work > > patches. It will posted once prep-work completes. > > > > [1] https://www.spinics.net/lists/netdev/msg556978.html > > [2] https://lkml.org/lkml/2019/3/7/696 > > [3] https://lkml.org/lkml/2019/3/8/819 > > [4] https://netdevconf.org/0x13/session.html?workshop-hardware-offload > > > > --- > > Changelog: > > --- > > v1->v2: > > - Addressed comments from Alex > > - Rebased > > - Inserted the device checking loop in Patch-6 as original code > > - Added patch 7 to 10 > > - Added fixes for race condition in create/remove with parent removal > > Patch-10 uses simplified refcount and completion, instead of srcu > > which might take seconds to minutes on busy system. > > - Added fix for device create/remove sequence to match > > Linux device, bus model > > v0->v1: > > - Dropped device placement on bus sequence patch for this series > > - Addressed below comments from Alex, Kirti, Maxim. > > - Added Review-by tag for already reviewed patches. > > - Dropped incorrect patch of put_device(). > > - Corrected Fixes commit tag for sysfs remove sequence fix > > - Split last 8th patch to smaller refactor and fixes patch > > - Following coding style commenting format > > - Fixed accidental delete of mutex_lock in mdev_unregister_device > > - Renamed remove helped to mdev_device_remove_common(). > > - Rebased for uuid/guid change > > > > Parav Pandit (10): > > vfio/mdev: Avoid release parent reference during error path > > vfio/mdev: Removed unused kref > > vfio/mdev: Drop redundant extern for exported symbols > > vfio/mdev: Avoid masking error code to EBUSY > > vfio/mdev: Follow correct remove sequence > > vfio/mdev: Fix aborting mdev child device removal if one fails > > vfio/mdev: Avoid inline get and put parent helpers > > vfio/mdev: Improve the create/remove sequence > > vfio/mdev: Avoid creating sysfs remove file on stale device removal > > vfio/mdev: Synchronize device create/remove with parent removal > > > > drivers/vfio/mdev/mdev_core.c | 162 +++++++++++++------------------ > > drivers/vfio/mdev/mdev_private.h | 9 +- > > drivers/vfio/mdev/mdev_sysfs.c | 8 +- > > include/linux/mdev.h | 21 ++-- > > 4 files changed, 89 insertions(+), 111 deletions(-) > > > > Hi Parav, > > I applied 1-7 to the vfio next branch for v5.2 since these are mostly > previously reviewed or trivial. I'm not ruling out the rest for v5.2 as bug fixes > yet, but they require a bit more to digest and hopefully we'll get some > feedback from others as well. Thanks, > Ok. Great. Yes, these are important for us to make use of mdev. We should address them in 5.2 window. I will look for any comments this week and address them as required.
