Increase maximum number of Infiniband HCAs per system

This is v2 of a patch series that increases the maximum number of IB HCAs supported per system.

The original mail thread is here:

	http://lkml.org/lkml/2010/1/29/346

One note, I decided to "copy/paste" since factoring out the overflow code in the three drivers seemed like overkill. If so desired, I could factor those three separate functions into something provided by the core, but that seemed like more trouble than it was worth at the time.

As before, I still don't have access to a giant system, so what I did to test was to stick 4 cards into a small system, and then modify the limits with debug patches similar to this:

index 7bf0a82..8581e64 100644
@@ -102,7 +102,7 @@ struct ib_ucm_event {
 enum {
        IB_UCM_MAJOR = 231,
        IB_UCM_BASE_MINOR = 224,
-       IB_UCM_MAX_DEVICES = 32
+       IB_UCM_MAX_DEVICES = 2
 };
 
 

I tested all 3 drivers this way (uverbs, umad, ucm). I verified that we're not leaking device numbers on multiple modprobe/rmmod cycles, that there aren't any funny interactions when various combinations of the drivers are loaded.

I did not test the rest of the OFED stack. I did write some trivial programs to open the devices in /dev and close them again.

Here's an example of some of the testing:

	dl585g2:~ # modprobe ib_uverbs
	dl585g2:~ # modprobe ib_umad
	dl585g2:~ # modprobe ib_ucm
	dl585g2:~ # ls -l /dev/uverb*
	crw-rw---- 1 root root 231, 192 Feb  2 05:55 /dev/uverbs0
	crw-rw---- 1 root root 231, 193 Feb  2 05:55 /dev/uverbs1
	crw-rw---- 1 root root 249,   0 Feb  2 05:55 /dev/uverbs2
	crw-rw---- 1 root root 249,   1 Feb  2 05:55 /dev/uverbs3
	dl585g2:~ # ls -l /dev/umad*
	crw-rw---- 1 root root 231, 0 Feb  2 05:55 /dev/umad0
	crw-rw---- 1 root root 231, 1 Feb  2 05:55 /dev/umad1
	crw-rw---- 1 root root 231, 2 Feb  2 05:55 /dev/umad2
	crw-rw---- 1 root root 231, 3 Feb  2 05:55 /dev/umad3
	crw-rw---- 1 root root 248, 0 Feb  2 05:55 /dev/umad4
	crw-rw---- 1 root root 248, 1 Feb  2 05:55 /dev/umad5
	crw-rw---- 1 root root 248, 2 Feb  2 05:55 /dev/umad6
	crw-rw---- 1 root root 248, 3 Feb  2 05:55 /dev/umad7
	dl585g2:~ # ls -l /dev/issm*
	crw-rw---- 1 root root 231, 4 Feb  2 05:55 /dev/issm0
	crw-rw---- 1 root root 231, 5 Feb  2 05:55 /dev/issm1
	crw-rw---- 1 root root 231, 6 Feb  2 05:55 /dev/issm2
	crw-rw---- 1 root root 231, 7 Feb  2 05:55 /dev/issm3
	crw-rw---- 1 root root 248, 4 Feb  2 05:55 /dev/issm4
	crw-rw---- 1 root root 248, 5 Feb  2 05:55 /dev/issm5
	crw-rw---- 1 root root 248, 6 Feb  2 05:55 /dev/issm6
	crw-rw---- 1 root root 248, 7 Feb  2 05:55 /dev/issm7
	dl585g2:~ # ls -l /dev/ucm*
	crw-rw---- 1 root root 231, 224 Feb  2 05:55 /dev/ucm0
	crw-rw---- 1 root root 231, 225 Feb  2 05:55 /dev/ucm1
	crw-rw---- 1 root root 247,   0 Feb  2 05:55 /dev/ucm2
	crw-rw---- 1 root root 247,   1 Feb  2 05:55 /dev/ucm3

Note that the major and minor numbers are behaving rather sanely.

	dl585g2:~ # rmmod ib_ucm
	dl585g2:~ # rmmod ib_uverbs
	dl585g2:~ # rmmod ib_umad

Reset.

	dl585g2:~ # modprobe ib_ucm
	dl585g2:~ # ls -l /dev/ucm*
	crw-rw---- 1 root root 231, 224 Feb  2 05:57 /dev/ucm0
	crw-rw---- 1 root root 231, 225 Feb  2 05:57 /dev/ucm1
	crw-rw---- 1 root root 248,   0 Feb  2 05:57 /dev/ucm2
	crw-rw---- 1 root root 248,   1 Feb  2 05:57 /dev/ucm3

See that /dev/ucm* devices now have a different major number compared to last time(248 vs 247), since we loaded that driver first.

But wait, why is it 248 and not 249? Is there a leak somewhere?

	dl585g2:~ # ls -l /dev/uverb*
	crw-rw---- 1 root root 231, 192 Feb  2 05:57 /dev/uverbs0
	crw-rw---- 1 root root 231, 193 Feb  2 05:57 /dev/uverbs1
	crw-rw---- 1 root root 249,   0 Feb  2 05:57 /dev/uverbs2
	crw-rw---- 1 root root 249,   1 Feb  2 05:57 /dev/uverbs3
	dl585g2:~ # rmmod ib_uverbs
	ERROR: Module ib_uverbs is in use by ib_ucm

Ah, ib_ucm is dependent on ib_uverbs, so when we modprobed ib_ucm, in reality ib_uverbs got loaded first. See how it has a higher major number.

	dl585g2:~ # rmmod ib_ucm
	dl585g2:~ # rmmod ib_uverbs
	dl585g2:~ # modprobe ib_umad
	dl585g2:~ # ls -l /dev/umad*
	crw-rw---- 1 root root 231, 0 Feb  2 05:58 /dev/umad0
	crw-rw---- 1 root root 231, 1 Feb  2 05:58 /dev/umad1
	crw-rw---- 1 root root 231, 2 Feb  2 05:58 /dev/umad2
	crw-rw---- 1 root root 231, 3 Feb  2 05:58 /dev/umad3
	crw-rw---- 1 root root 249, 0 Feb  2 05:58 /dev/umad4
	crw-rw---- 1 root root 249, 1 Feb  2 05:58 /dev/umad5
	crw-rw---- 1 root root 249, 2 Feb  2 05:58 /dev/umad6
	crw-rw---- 1 root root 249, 3 Feb  2 05:58 /dev/umad7
	dl585g2:~ # ls -l /dev/issm*
	crw-rw---- 1 root root 231, 4 Feb  2 05:58 /dev/issm0
	crw-rw---- 1 root root 231, 5 Feb  2 05:58 /dev/issm1
	crw-rw---- 1 root root 231, 6 Feb  2 05:58 /dev/issm2
	crw-rw---- 1 root root 231, 7 Feb  2 05:58 /dev/issm3
	crw-rw---- 1 root root 249, 4 Feb  2 05:58 /dev/issm4
	crw-rw---- 1 root root 249, 5 Feb  2 05:58 /dev/issm5
	crw-rw---- 1 root root 249, 6 Feb  2 05:58 /dev/issm6
	crw-rw---- 1 root root 249, 7 Feb  2 05:58 /dev/issm7

Finally, after one more reset, we see ib_umad loaded first and obtaining the major number of 249.

v1 -> v2:
- update umad and ucm drivers too

---

Alex Chiang (18):
IB/uverbs: convert *cdev to cdev in struct ib_uverbs_device IB/uverbs: remove dev_table
IB/uverbs: use stack variable 'devnum' in ib_uverbs_add_one IB/uverbs: use stack variable 'base' in ib_uverbs_add_one IB/uverbs: increase maximum devices supported
IB/uverbs: pack struct ib_uverbs_event_file tighter IB/uverbs: whitespace cleanup
IB/umad: convert cdev pointers to embedded structs in struct ib_umad_port IB/umad: remove port_table[]
IB/umad: use stack variable 'devnum' in ib_umad_init_port IB/umad: use stack variable 'base' in ib_umad_init_port IB/umad: increase maximum devices supported
IB/umad: clean whitespace
IB/ucm: use stack variable 'devnum' in ib_ucm_add_one IB/ucm: use stack variable 'base' in ib_ucm_add_one
IB/ucm: increase maximum devices supported
IB/ucm: clean whitespace errors
IB/core: pack struct ib_device a little tighter

 drivers/infiniband/core/ucm.c         |   63 ++++++++++--
 drivers/infiniband/core/user_mad.c    |  173 +++++++++++++++++----------------
 drivers/infiniband/core/uverbs.h      |   11 +-
 drivers/infiniband/core/uverbs_main.c |  175 +++++++++++++++++++--------------
 include/rdma/ib_verbs.h               |    4 -
 5 files changed, 255 insertions(+), 171 deletions(-)

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