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SubjectRe: [PATCH v2 00/18] Increase maximum number of Infiniband HCAs per system
Hi Roland,

Any thoughts on this patch series?

Thanks,
/ac

* Alex Chiang <achiang@hp.com>:
> 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:
>
> diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
> index 7bf0a82..8581e64 100644
> --- a/drivers/infiniband/core/ucm.c
> +++ b/drivers/infiniband/core/ucm.c
> @@ -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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