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Commit Graph

85 Commits

Author SHA1 Message Date
Anton Blanchard
1f79448302 IB/ehca: Make output clearer by removing some debug messages
ehca spits out a lot of debugging information. I had to look closely to
see the "Port 1 is not active" message within all the debug:

eHCA Infiniband Device Driver (Rel.: SVNEHCA_0022)
eHCA scaling code enabled
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_define_sqp Port 1 is not active.
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_create_qp ehca_define_sqp() failed rc=ffffffffffffffff
ib_mad: Couldn't create ib_mad QP1
ib_mad: Couldn't open ehca0 port 1
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_alloc_fmr unsupported fmr_attr->page_shift=9
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_alloc_fmr rc=ffffffffffffffea pd=c000000b4b5b2420 mr_access_flags=7 fmr_attr=c0000005afd37394
fmr_create failed for FMR 0

Remove a few debug statements so that things are clearer:

eHCA Infiniband Device Driver (Rel.: SVNEHCA_0022)
eHCA scaling code enabled
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_define_sqp Port 1 is not active.
ib_mad: Couldn't create ib_mad QP1
ib_mad: Couldn't open ehca0 port 1
ehca D.001.DQDXYCB-P1-C9: PU0006 EHCA_ERR:ehca_alloc_fmr unsupported fmr_attr->page_shift=9
fmr_create failed for FMR 0

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-10-09 19:59:06 -07:00
Roland Dreier
1fea391039 IB/ehca: Include <linux/mutex.h> from ehca_classes.h
ehca_classes.h uses struct mutex, so while <linux/mutex.h> seems to be
pulled in indirectly by one of the headers it includes, the right
thing is to include <linux/mutex.h> directly.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Acked-by: Stefan Roscher <stefan.roscher@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-10-09 19:59:05 -07:00
Joachim Fenkes
5ff70cac3e IB/ehca: SRQ fixes to enable IPoIB CM
Fix ehca SRQ support so that IPoIB connected mode works:

 - Report max_srq > 0 if SRQ is supported
 - Report "last wqe reached" asynchronous event when base QP dies;
   this is required by the IB spec and IPoIB CM relies on receiving it
   when cleaning up.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-08-31 13:58:04 -07:00
Stefan Roscher
fecea0ab34 IB/ehca: Fix Small QP regressions
The new Small QP code had a few bugs that would also make it trigger
for non-Small QPs.  Fix them.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-08-31 13:56:42 -07:00
Eddy L O Jansson
0e6ff1580f in-string typos of "error"
One patch for two trivial typos of 'error' with three R's, appearing in message strings.

There's a bunch more of the same in comments, not dealt with here.

Signed-off-by: Eddy L O Jansson <eddy@klopper.net>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-31 15:39:40 -07:00
Hoang-Nam Nguyen
1655fc2e12 IB/ehca: Move extern declarations from .c files to .h files
Make sure declarations stay in sync with definitions by keeping all 
extern declarations in common .h files.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-28 21:47:53 -07:00
Hoang-Nam Nguyen
05d989f948 IB/ehca: Fix include order to better match kernel style
Include <rdma/...> headers after <asm/...> headers.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-28 08:36:32 -07:00
Stefan Roscher
e2f81daf23 IB/ehca: Support small QP queues
eHCA2 supports QP queues that can be as small as 512 bytes. This
greatly reduces memory overhead for consumers that use lots of QPs
with small queues (e.g. RDMA-only QPs). Apart from dealing with
firmware, this code needs to manage bite-sized chunks of kernel pages,
making sure that no kernel page is shared between different protection
domains.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
2007-07-20 21:19:47 -07:00
Joachim Fenkes
0c10f7b79b IB/ehca: Make internal_create/destroy_qp() static
They're only used in ehca_qp.c, so make them static to that file.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-20 21:19:44 -07:00
Hoang-Nam Nguyen
51d2bfbddb IB/ehca: Move ehca2ib_return_code() out of line
ehca2ib_return_code() is not used in any fast path, and making it
non-inline saves ~1.5K of code.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-20 21:19:44 -07:00
Hoang-Nam Nguyen
633a5aedae IB/ehca: Generate async event when SRQ limit reached
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-20 21:19:44 -07:00
Hoang-Nam Nguyen
5bb7d9290c IB/ehca: Support large page MRs
Add support for MR pages larger than 4K on eHCA2. This reduces
firmware memory consumption.  If enabled via the mr_largepage module
parameter, the MR page size will be determined based on the MR length
and the hardware capabilities -- if the MR is >= 16M, 16M pages are
used, for example.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-20 21:19:43 -07:00
Paul Mundt
20c2df83d2 mm: Remove slab destructors from kmem_cache_create().
Slab destructors were no longer supported after Christoph's
c59def9f22 change. They've been
BUGs for both slab and slub, and slob never supported them
either.

This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-07-20 10:11:58 +09:00
Hoang-Nam Nguyen
2b94397adc IB/ehca: Fix warnings issued by checkpatch.pl
Run the existing ehca code through checkpatch.pl and clean up the
worst of the coding style violations.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:40 -07:00
Hoang-Nam Nguyen
187c72e31f IB/ehca: Restructure ehca_set_pagebuf()
Split ehca_set_pagebuf() into three functions depending on MR type
(phys/user/fast) and remove superfluous ehca_set_pagebuf_1().

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:40 -07:00
Hoang-Nam Nguyen
df17bfd4a0 IB/ehca: MR/MW structure refactoring
- Rename struct ehca_mr fields to clearly distinguish between kernel
  and HW page size.
- Sort struct ehca_mr_pginfo into a common part and a union containing
  specific fields for physical, user and fast MR

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:40 -07:00
Hoang-Nam Nguyen
2492398e61 IB/ehca: Use macro to calculate number of chunks in a mem block
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:39 -07:00
Hoang-Nam Nguyen
4e4e74cae7 IB/ehca: Use #define for "pages per register_rpage" instead of hardcoded value
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:39 -07:00
Hoang-Nam Nguyen
a1a6ff1100 IB/ehca: Use common error code mapping instead of specific ones
Instead of one error mapping function for each potential error source
in ehca_mrmw.c, use a centralized function that handles all cases,
saving a three-figure line count.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:39 -07:00
Hoang-Nam Nguyen
3df78f81e0 IB/ehca: Fix memory leak in error path of ehca_get_dma_mr()
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:39 -07:00
Joachim Fenkes
fbb9318be4 IB/ehca: Fix HW level autodetection
Autodetection was missing a few HW revisions, causing certain eHCA1
revisions to be treated like eHCA2.  Fixed.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-17 18:37:39 -07:00
Hoang-Nam Nguyen
f72d2f0814 IB/ehca: Improve latency by unlocking after triggering the hardware
Kick the hardware before unlocking the send/receive queue to overlap
processing a little more.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
8705ce5b90 IB/ehca: Notify consumers of LID/PKEY/SM changes after nondisruptive events
When firmware reports a nondisruptive port configuration change event,
previous versions of the eHCA driver didn't forward the event to consumers
like IPoIB.  Add code that determines the type of configuration change by
comparing old and new port attributes and reports it.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
b1cfe43d4b IB/ehca: Return QP pointer in poll_cq()
Also add two unlikely() statements.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
26ed687fdd IB/ehca: Change idr spinlocks into rwlocks
This eliminates lock contention among IRQs as well as the need to
disable IRQs around idr_find, because there are no IRQ writers.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
28db6beb42 IB/ehca: Refactor sync between completions and destroy_cq using atomic_t
- ehca_cq.nr_events is made an atomic_t, eliminating a lot of locking.
- The CQ is removed from the CQ idr first now to make sure no more
  completions are scheduled on that CQ. The "wait for all completions to
  end" code becomes much simpler this way.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
9844b71baa IB/ehca: Lock renaming, static initializers
- Rename all spinlock flags to "flags", matching the vast majority of kernel
  code.
- Move hcall_lock into the only file it's used in.
- Replaced spin_lock_init() and friends with static initializers for
  global variables.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Hoang-Nam Nguyen
15f001ec47 IB/ehca: Report RDMA atomic attributes in query_qp()
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Stefan Roscher
85f003172f IB/ehca: Set SEND_GRH flag for all non-LL UD QPs on eHCA2
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Stefan Roscher
472803dab8 IB/ehca: Support UD low-latency QPs
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
a6a12947fb IB/ehca: add Shared Receive Queue support
Support SRQs on eHCA2. Since an SRQ is a QP for eHCA2, a lot of code
(structures, create, destroy, post_recv) can be shared between QP and SRQ.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
9a79fc0a1b IB/ehca: QP code restructuring in preparation for SRQ
- Replace init_qp_queues() by a shorter init_qp_queue(), eliminating
  duplicate code.

- hipz_h_alloc_resource_qp() doesn't need a pointer to struct ehca_qp any
  longer. All input and output data is transferred through the parms
  parameter.

- Change the interface to also support SRQ.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Joachim Fenkes
91f13aa3fc IB/ehca: HW level, HW caps and MTU autodetection
In preparation for support of new eHCA2 features, change adapter probing:
 - Hardware level is changed to encode major and minor chip version
 - Hardware capabilities are queried from the firmware
 - The maximum MTU is queried from the firmware instead of assuming a
   fixed value

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:27 -07:00
Hoang-Nam Nguyen
b8a3ba5513 IB/ehca: Change scaling_code parameter description to match default value
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:26 -07:00
Jan Engelhardt
06cc85086e IB: Use menuconfig for InfiniBand menu
Change Kconfig objects from "menu, config" into "menuconfig" so
that the user can disable the whole feature without having to
enter the menu first.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 20:12:26 -07:00
Joachim Fenkes
fffba373ef IB/ehca: Refactor "maybe missed event" code
Refactor the ehca changes from commit ed23a727 ("IB: Return "maybe
missed event" hint from ib_req_notify_cq()") so the queue arithmetic
is done in slightly fewer lines.  Also, move the spinlock flags into
the block they're used in.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-07-09 16:17:32 -07:00
Stefan Roscher
65a2c841d6 IB/ehca: Fix number of send WRs reported for new QP
Due to a typo, the driver was reporting the wrong number of "actual send
WRs" after ehca_create_qp().

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-24 14:02:39 -07:00
Hoang-Nam Nguyen
bd5a6ccc0e IB/ehca: Return proper error code if register_mr fails
Set the return code of ehca_register_mr() to ENOMEM if the corresponding
firmware call fails due to out of resources.  Some other error codes
were explicitly mapped to EINVAL -- just remove those cases so they
get mapped to the default case, which already returns EINVAL anyway.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-19 08:51:54 -07:00
Joachim Fenkes
4e430dcb7b IB/ehca: Disable scaling code by default, bump version number
- Scaling code is still considered experimental, so disable it by default
- Increase version to SVNEHCA_0023

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:41:40 -07:00
Joachim Fenkes
bba9b6013e IB/ehca: Beautify sysfs attribute code and fix compiler warnings
eHCA's sysfs attributes are now being created via sysfs_create_group(),
making the process neatly table-driven. The return value is checked, thus
fixing a few compiler warnings.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:40:45 -07:00
Joachim Fenkes
c7a14939e7 IB/ehca: Remove _irqsave, move #ifdef
- In ehca_process_eq(), we're IRQ safe throughout the whole function, so we
  don't need another _irqsave in the middle of flight.

- take_over_work() is only called by comp_pool_callback(), so it can move
  into the same #ifdef block.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:40:05 -07:00
Hoang-Nam Nguyen
c55a0ddd8e IB/ehca: Fix AQP0/1 QP number
AQP0/1 should report qp_num={0|1} and the actual QP# should be stored
in struct ehca_qp, not the other way round.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:39:31 -07:00
Joachim Fenkes
92761cdaf2 IB/ehca: Correctly set GRH mask bit in ehca_modify_qp()
The driver needs to always supply the "GRH present" flag to the
hypervisor, whether it's true or false. Not supplying it (i.e. not
setting the corresponding mask bit) amounts to a "perhaps", which we
don't want.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:38:57 -07:00
Stefan Roscher
5d88278e3b IB/ehca: Serialize hypervisor calls in ehca_register_mr()
Some pSeries hypervisor versions show a race condition in the allocate
MR hCall.  Serialize this call per adapter to circumvent this problem.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-14 13:38:11 -07:00
Linus Torvalds
de5603748a Merge branch 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/roland/infiniband
* 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/roland/infiniband:
  IB/mlx4: Add a driver Mellanox ConnectX InfiniBand adapters
  IB: Put rlimit accounting struct in struct ib_umem
  IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules
2007-05-09 19:40:09 -07:00
Rafael J. Wysocki
8bb7844286 Add suspend-related notifications for CPU hotplug
Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:56 -07:00
Roland Dreier
f7c6a7b5d5 IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules
Export ib_umem_get()/ib_umem_release() and put low-level drivers in
control of when to call ib_umem_get() to pin and DMA map userspace,
rather than always calling it in ib_uverbs_reg_mr() before calling the
low-level driver's reg_user_mr method.

Also move these functions to be in the ib_core module instead of
ib_uverbs, so that driver modules using them do not depend on
ib_uverbs.

This has a number of advantages:
 - It is better design from the standpoint of making generic code a
   library that can be used or overridden by device-specific code as
   the details of specific devices dictate.
 - Drivers that do not need to pin userspace memory regions do not
   need to take the performance hit of calling ib_mem_get().  For
   example, although I have not tried to implement it in this patch,
   the ipath driver should be able to avoid pinning memory and just
   use copy_{to,from}_user() to access userspace memory regions.
 - Buffers that need special mapping treatment can be identified by
   the low-level driver.  For example, it may be possible to solve
   some Altix-specific memory ordering issues with mthca CQs in
   userspace by mapping CQ buffers with extra flags.
 - Drivers that need to pin and DMA map userspace memory for things
   other than memory regions can use ib_umem_get() directly, instead
   of hacks using extra parameters to their reg_phys_mr method.  For
   example, the mlx4 driver that is pending being merged needs to pin
   and DMA map QP and CQ buffers, but it does not need to create a
   memory key for these buffers.  So the cleanest solution is for mlx4
   to call ib_umem_get() in the create_qp and create_cq methods.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-08 18:00:37 -07:00
Paul Mackerras
02bbc0f09c Merge branch 'linux-2.6' 2007-05-08 13:37:51 +10:00
Linus Torvalds
972d45fb43 Merge branch 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/roland/infiniband
* 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/roland/infiniband:
  IPoIB: Convert to NAPI
  IB: Return "maybe missed event" hint from ib_req_notify_cq()
  IB: Add CQ comp_vector support
  IB/ipath: Fix a race condition when generating ACKs
  IB/ipath: Fix two more spin lock problems
  IB/fmr_pool: Add prefix to all printks
  IB/srp: Set proc_name
  IB/srp: Add orig_dgid sysfs attribute to scsi_host
  IPoIB/cm: Don't crash if remote side uses one QP for both directions
  RDMA/cxgb3: Support for new abort logic
  RDMA/cxgb3: Initialize cpu_idx field in cpl_close_listserv_req message
  RDMA/cxgb3: Fail qp creation if the requested max_inline is too large
  RDMA/cxgb3: Fix TERM codes
  IPoIB/cm: Fix error handling in ipoib_cm_dev_open()
  IB/ipath: Don't corrupt pending mmap list when unmapped objects are freed
  IB/mthca: Work around kernel QP starvation
  IB/ipath: Don't put QP in timeout queue if waiting to send
  IB/ipath: Don't call spin_lock_irq() from interrupt context
2007-05-07 12:18:21 -07:00
Roland Dreier
ed23a72778 IB: Return "maybe missed event" hint from ib_req_notify_cq()
The semantics defined by the InfiniBand specification say that
completion events are only generated when a completions is added to a
completion queue (CQ) after completion notification is requested.  In
other words, this means that the following race is possible:

	while (CQ is not empty)
		ib_poll_cq(CQ);
	// new completion is added after while loop is exited
	ib_req_notify_cq(CQ);
	// no event is generated for the existing completion

To close this race, the IB spec recommends doing another poll of the
CQ after requesting notification.

However, it is not always possible to arrange code this way (for
example, we have found that NAPI for IPoIB cannot poll after
requesting notification).  Also, some hardware (eg Mellanox HCAs)
actually will generate an event for completions added before the call
to ib_req_notify_cq() -- which is allowed by the spec, since there's
no way for any upper-layer consumer to know exactly when a completion
was really added -- so the extra poll of the CQ is just a waste.

Motivated by this, we add a new flag "IB_CQ_REPORT_MISSED_EVENTS" for
ib_req_notify_cq() so that it can return a hint about whether the a
completion may have been added before the request for notification.
The return value of ib_req_notify_cq() is extended so:

	 < 0	means an error occurred while requesting notification
	== 0	means notification was requested successfully, and if
		IB_CQ_REPORT_MISSED_EVENTS was passed in, then no
		events were missed and it is safe to wait for another
		event.
	 > 0	is only returned if IB_CQ_REPORT_MISSED_EVENTS was
		passed in.  It means that the consumer must poll the
		CQ again to make sure it is empty to avoid the race
		described above.

We add a flag to enable this behavior rather than turning it on
unconditionally, because checking for missed events may incur
significant overhead for some low-level drivers, and consumers that
don't care about the results of this test shouldn't be forced to pay
for the test.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-05-06 21:18:11 -07:00