[net-next,v2,00/11] implement DEVLINK_CMD_REGION_NEW

This is a second revision of the previous series to implement the
DEVLINK_CMD_REGION_NEW. The series can be viewed on lore.kernel.org at

https://lore.kernel.org/netdev/20200324223445.2077900-1-jacob.e.keller@intel.com/

This version includes the suggested cleanups from Jakub and Jiri on the
list, including the following changes, broken out by the v1 patch title.

Changes to patches since v1:

 * devlink: prepare to support region operations

   No changes

 * devlink: convert snapshot destructor callback to region op

   No changes

 * devlink: trivial: fix tab in function documentation

   No changes

 * devlink: add function to take snapshot while locked

   Added Jakub's Reviewed-by tag.

 * <NEW> devlink: use -ENOSPC to indicate no more room for snapshots

   New patch added to convert confusing -ENOMEM to -ENOSPC, as suggested by
   Jiri.

 * devlink: extract snapshot id allocation to helper function

   No changes

 * devlink: convert snapshot id getter to return an error

   Changed title to "devlink: report error once U32_MAX snapshot ids have
   been used".

   Refactored this patch to make devlink_region_snapshot_id_get take a
   pointer to u32, so that the error value and id value are separated. This
   means that we can remove the INT_MAX limitation on id values.

 * devlink: track snapshot id usage count using an xarray

   Fixed the xa_init to use xa_init_flags with XA_FLAGS_ALLOC, so that
   xa_alloc can properly be used.

   Changed devlink_region_snapshot_id_get to use an initial count of 1
   instead of 0. Added a new devlink_region_snapshot_id_put function, used
   to release this initial count. This closes the race condition and issues
   caused if the driver either doesn't create a snapshot, or if userspace
   deletes the first snapshot before others are created.

   Used WARN_ON in a few more checks that should not occur, such as if the
   xarray entry is not a value, or when the id isn't yet in the xarray.

   Removed an unnecessary if (err) { return err; } construction.

   Use xa_limit_32b instead of xa_limit_31b now that we don't return the
   snapshot id directly.

   Cleanup the label used in __devlink_region_snapshot_create to indicate the
   failure cause, rather than the cleanup step.

   Removed the unnecessary locking around xa_destroy

 * devlink: implement DEVLINK_CMD_REGION_NEW

   Added a WARN_ON to the check in snapshot_id_insert in case the id already
   exists.

   Removed an unnecessary "if (err) { return err; }" construction

   Use -ENOSPC instead of -ENOMEM when max_snapshots is reached.

   Cleanup label names to match style of the other labels in the file,
   naming after the failure cause rather than the cleanup step. Also fix a
   bug in the label ordering.

   Call the new devlink_region_snapshot_id_put function in the mlx4 and
   netdevsim drivers.

 * netdevsim: support taking immediate snapshot via devlink

   Create a local devlink pointer instead of calling priv_to_devlink
   multiple times.

   Removed previous selftest for devlink region new without a snapshot id,
   as this is no longer supported. Adjusted and verified that the tests pass
   now.

 * ice: add a devlink region for dumping NVM contents

   Use "dev_err" instead of "dev_warn" for a message about failure to create
   the devlink region.

Jacob Keller (11):
  devlink: prepare to support region operations
  devlink: convert snapshot destructor callback to region op
  devlink: trivial: fix tab in function documentation
  devlink: add function to take snapshot while locked
  devlink: use -ENOSPC to indicate no more room for snapshots
  devlink: extract snapshot id allocation to helper function
  devlink: report error once U32_MAX snapshot ids have been used
  devlink: track snapshot id usage count using an xarray
  devlink: implement DEVLINK_CMD_REGION_NEW
  netdevsim: support taking immediate snapshot via devlink
  ice: add a devlink region for dumping NVM contents

 .../networking/devlink/devlink-region.rst     |   8 +
 Documentation/networking/devlink/ice.rst      |  26 ++
 drivers/net/ethernet/intel/ice/ice.h          |   2 +
 drivers/net/ethernet/intel/ice/ice_devlink.c  |  99 +++++
 drivers/net/ethernet/intel/ice/ice_devlink.h  |   3 +
 drivers/net/ethernet/intel/ice/ice_main.c     |   4 +
 drivers/net/ethernet/mellanox/mlx4/crdump.c   |  36 +-
 drivers/net/netdevsim/dev.c                   |  46 ++-
 include/net/devlink.h                         |  33 +-
 net/core/devlink.c                            | 363 +++++++++++++++---
 .../drivers/net/netdevsim/devlink.sh          |  10 +
 11 files changed, 550 insertions(+), 80 deletions(-)