Create ida helpers and use them

As pointed out by Christoph Hellwig, many of the users of the ida index routines call them with the same calling pattern, so why not make some helper functions to help clean up and simplify the code a bit.

After looking at all the uses of the ida routines, I noticed that most of clients of this API used the same sequence -- but not all of them. So I picked the most common and seemingly most correct sequence, and I made inline helper functions for that, creating:

- ida_get_index() -- get an 'ida' index, with proper locking and retry

- ida_put_index() -- release/return an index allocated by ida_get_index(), with proper locking

I converted the following drivers to use the new helper routines, because they matched the calling sequence used by the helper functions:

  scsi/sd.c                     SCSI disk
  base/soc.c                    sound?
  block/mtip32xxx/mtip32xx.c    PCI block?
  block/nvme-core.c             Intel SSD?
  block/rsxx/core.c             IBM Flash?

Obviously, only one of these is a SCSI driver, so I hope this is still the right place to post this.

NOTE 1: the soc.c driver actually had normal locking around it's 'get' call, but it had no locking around it's 'put' (release) calls, so since the helper routines have locking, that means the soc.c driver now has locking when it releases an index.

There were other drivers that used ida in a way that meant I could not easily modify them:

drivers/iommu/iommu.c:
- uses unlikely(...)
- uses a mutex instead of spinlock

drivers/misc/cb710/core.c:
- calls return from within the 'get' while loop
- uses spin_lock_irq*()

drivers/scsi/osd/osd_uld.c:
- uses no locking at all for indexes [See NOTE 2]

drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c
- uses 'unlikely()' in 'get' while loop
- uses 'goto's out of 'get' while loop

NOTE 2: Not sure if this is a bug in the osd code, since I did not look at it very closely.

The only client driver changes I was able to functionally test where the sd.c changes. I also tested the helper functions using the hosts.c module, where they worked fine, but those changes were later reverted in favor of using idr there instead. (See previous patch series.)

Lee Duncan (6):
Add ida helper routines
SCSI: Update sd driver to use new ida helper functions. Update soc driver to use new ida helper functions. Update soc driver to use new ida helper functions. Update nvme-core driver to use new ida helper functions. Update rsxx core driver to use new ida helper functions.

 drivers/base/soc.c                | 17 +++-------------
 drivers/block/mtip32xx/mtip32xx.c | 22 ++++----------------
 drivers/block/nvme-core.c         | 14 ++-----------
 drivers/block/rsxx/core.c         | 16 ++-------------
 drivers/scsi/sd.c                 | 18 +++--------------
 include/linux/idr.h               | 42 +++++++++++++++++++++++++++++++++++++++
 6 files changed, 56 insertions(+), 73 deletions(-)

2.1.4