Revert "Create per RCU flavor CDS libraries"

This reverts commit d4b99c015229978810319cfd42e1c9763772fad8.

Minor change (not visible to end-users): this commit introduces a
liburcu-common.so to hold wfqueue, wfstack and futex fall-back code.
This .so is used by all URCU flavors, as well as liburcu-cds.so.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Revert "CDS API: removal of rcu_read lock/unlock dep, removal of call_rcu argument from init"

This reverts commit 7618919ae496bda84a2efa4f2ad0abe569892a9e.

Rationale:

I thought about it some more, and had discussions with various people,
and there are a few reasons to go for a scheme where rcu read lock
should be taken by the caller, and to pass call_rcu as a parameter to
the data structure init function:

A) The advantage, as Paul E. McKenney pointed out, is that one single .so
   is enough to support all RCU flavors. Very convenient for external data
   structure containers.

B) It clearly documents where rcu read-side locks are needed, so the user
   keep control and in-depth understanding of their read-side locks.

C) When multiple API functions that require RCU read-side lock to be
   held (sometimes even the same lock) throughout a sequence of API
   calls, we have no choice but to let the caller hold the read-side
   lock.

D) Due to support of multiple nesting of rcu read-side lock, any
   "improvement" we could get by releasing the read-side lock in
   retry loops would vanish in the cases where we are called within
   nested C.S..

E) If a library uses synchronize_rcu, this should be clearly documented,
   and even frowned upon, because this involves important limitations on
   the design of the caller, and important performance hit. There are
   usually ways to reach the same result through use of call_rcu, which
   should really be used thoroughout these libraries.

F) It clearly documents when a data structure needs to use call_rcu
   internally.

G) Some very early benchmark results show that there is indeed not
   much performance gain to achieve by inlining call_rcu, even if it is
   a version with a cache for the "call_rcu structure" lookup
   (per-cpu/per-thread/global). So passing it as a parameter to
   the data structure init function should be fine, even in cases
   where it is called very often.

H) For use-cases where applications would like to use more than one
   RCU flavor concurrently (which is now supported), leaving management
   of RCU read-side C.S. to the reader allows the application to take
   more than one RCU read-side lock across API calls. It also lets the
   application specify its own call_rcu function that could handle more
   than one RCU flavor.

So for all these reasons, I reverting back to the API we have in our
last release (0.6.4).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add __rcu annotation (unimplemented)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix incorrect fsf address in header files

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

wfstack: push returns prior stack emptiness state

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Make lf stack push return if the stack was empty

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Document caa_container_of

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: do not call munmap for NULL registry at exit

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu libraries can directly use the _LGPL_SOURCE wfqueue

No need to link dynamically with the data structure object.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfstack: document "push"

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add runall.sh to tarball

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix build order of liburcu-cds-common

Caused make install to fail.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

CDS API: removal of rcu_read lock/unlock dep, removal of call_rcu argument from init

* API change * for all liburcu-cds* flavors.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix missing check for SYS_membarrier in map header

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Create per RCU flavor CDS libraries

Introduce per-flavor concurrent data structure libraries for data
structures depending on RCU:

liburcu-cds: memb flavor (default), matches -lurcu
liburcu-cds-qsbr: qsbr flavor, matches -lurcu-qsbr
liburcu-cds-mb: mb flavor, matches -lurcu-mb
liburcu-cds-signal, matches -lurcu-signal
liburcu-cds-bp, matches -lurcu-bp

liburcu-cds-common: Data structures not depending on RCU for
synchronization.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Merge branch 'master' into lfqueue-dev

urcu-qsbr: avoid useless futex wakeups and burning CPU for long grace periods

I noticed that urcu makes exactly _one_ attempt at using futexes
to avoid busy looping on synchronize_rcu.  The attached patch instead
switches from busy waiting to futexes after RCU_QS_ACTIVE_ATTEMPTS.
To limit the amount of system calls, reading threads remember whether
they already had a quiescent state in this grace period; if so they were
already removed from the list, and can avoid signaling the futex.

Performance measured with rcutorture (nreaders: 10, nupdaters: 1,
duration: 10, median of nine runs):

     RCU_QS_ACTIVE_ATTEMPTS == 100, no patch         n_updates = 292
     RCU_QS_ACTIVE_ATTEMPTS == 1, no patch           n_updates = 290
     RCU_QS_ACTIVE_ATTEMPTS == 100, with patch       n_updates = 408
     RCU_QS_ACTIVE_ATTEMPTS == 1, with patch         n_updates = 404

(the first two cases are obviously the same; the only change is
when the futex is used, but over many calls there is no difference).

This patch matches the update to the Promela model.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

api: reimplement BUILD_BUG_ON in compiler.h

Even though it's just two lines of code, I'm reimplementing it
cleanly out of paranoia.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

test api cleanup: remove unused primitives

[ Mathieu: the rationale for this is that we can always add back that
  code if every needed. Removing leftover GPLv2 test code is an
  incentive to create the appropriate library-wide LGPL/MIT-style
  abstractions.]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Merge branch 'master' into lfqueue-dev

put thread offline while waiting for the init flag

Otherwise, the call_rcu thread might end up in a synchronize_rcu that
never ends.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS
and KICK_READER_LOOPS.  Move the definition to urcu.c.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS.
Move the definition to urcu-bp.c.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-qsbr: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS.
Move the definition to urcu-qsbr.c.  Also remove KICK_READER_LOOPS.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rcutorture: fix rcutorture-qsbr

rcutorture-qsbr is not marking quiescent states, so it will always
have just one update in the whole test.  Fix it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

wfqueue: fix type-incorrect assignment

The "old_tail = q->tail, q->tail = node" assignment in wfqueue
is not type safe; q->tail is a pointer to pointer to node and the
correct value to assign is &node->next.  While the arithmetic is
the same, it is better to be tidy.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix tests Makefile EXTRA_DIST to use api.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix choice of default flavour in urcu/map/urcu.h

Hi, I noticed in the 0.64 release (and git too) that if a flavour is not
specified explicitly then RCU_MB is chosen in urcu/map/urcu.h, while the
docs say and the Makefile expects RCU_MEMBARRIER.  Note that the header
file urcu/static/urcu.h has similar logic but uses RCU_MEMBARRIER for
the default.

Before this patch:

$ nm *.a | grep rcu_init
00000000000003c0 T rcu_init_mb
00000000000003c0 T rcu_init_mb
0000000000000000 T rcu_init_sig

After this patch:

$ nm *.a | grep rcu_init
00000000000003c0 T rcu_init_memb
00000000000003c0 T rcu_init_mb
0000000000000000 T rcu_init_sig

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

api: remove list/hlist

Remove the parts that actually caused compilation to fail.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

api: remove arch-specific files

No change since they were a subset of api_gcc.h.  api_gcc.h is
renamed to api.h, and configure need not create a symlink anymore.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

api: make api_gcc.h a superset of the other headers

After this patch the only differences are:

- for_each_tid is now defined in api_x86.h

- HAVE_CPU_SET_T and HAVE_SCHED_SETAFFINITY are now defined in api_ppc.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

tests api: remove atomics

The code is #if 0'd already, remove it.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

put thread offline while waiting for the init flag

Otherwise, the call_rcu thread might end up in a synchronize_rcu that
never ends.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS
and KICK_READER_LOOPS.  Move the definition to urcu.c.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS.
Move the definition to urcu-bp.c.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-qsbr: move private definitions to .c file

The reader does not and should not know about RCU_QS_ACTIVE_ATTEMPTS.
Move the definition to urcu-qsbr.c.  Also remove KICK_READER_LOOPS.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rcutorture: fix rcutorture-qsbr

rcutorture-qsbr is not marking quiescent states, so it will always
have just one update in the whole test.  Fix it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

wfqueue: fix type-incorrect assignment

The "old_tail = q->tail, q->tail = node" assignment in wfqueue
is not type safe; q->tail is a pointer to pointer to node and the
correct value to assign is &node->next.  While the arithmetic is
the same, it is better to be tidy.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Merge branch 'master' into lfqueue-dev

Use caa_ prefix for min() and max()

Defining min/max macros clashes with C++.

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Version 0.6.4, update changelog

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Merge branch 'master' into lfqueue-dev

Fix ARM uatomic: missing return in uatomic and/or

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfqueue: provide locklessness by allowing multiple dummy nodes

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rcu lfqueue: make dequeue lockless by helping out other dequeuers

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfqueue: Document dummy pointer value access

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfqueue: Keep a reference to the current dummy node rather than using low bit

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfqueue: only one dummy node is needed

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfstack: update comment

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

RCU lf queue: Add assert for memory allocation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfstack: header implementation should be defined as static inline

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

wfstack: header implementation should be defined as static inline

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

RCU lfqueue: Now works without reference counting (API change)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

rculfstack: header implementation should be defined as static inline

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

wfstack: header implementation should be defined as static inline

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu tests: hold mutex across use of custom allocator

A thread preempted for a long period of time could race, when scheduled
again, with another thread that would have been allocating/freeing
entries (thus wrapping-around the available buffer), which would trigger
this race only when overcommitting the number of threads compared to the
number of available CPUs.

Taking the mutex across alloc and free to fix this.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: mremap wrapper fix

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: add mremap wrapper for non-linux systems

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp: don't copy old region upon mremap

mremap keeps the same virtual pages for the old/new mappings. So
explicitly copying from the old mapping is not needed, and probably
buggy, since the old mapping might have been unmapped.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

api.h: fix type warning

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

non-linux system membarrier fallback update

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

pthread_self should be cast to unsigned long

Used as part of the random seed along with time().

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add MAP_ANONYMOUS mapping to MAP_ANON for BSD build

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

tests: only include syscall.h on linux systems

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-bp, urcu-qsbr: remove unneeded syscall.h include

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

urcu-defer: remove unneeded syscall.h include

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

call_rcu: per_cpu_call_rcu_data should be non-const

On FreeBSD:

In file included from urcu.c:438:
urcu-call-rcu-impl.h: In function 'get_cpu_call_rcu_data_mb':
urcu-call-rcu-impl.h:325: warning: return discards qualifiers from pointer target type

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Update README info about gcc compability

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix urcu-call-rcu-impl.h missing call_rcu_wait for non-linux systems

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

compat_futex_async: fix missing return

compat_futex.c: In function `compat_futex_async':
compat_futex.c:114: warning: control reaches end of non-void function

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Check for __linux__ before including syscall.h

Reported-by: Jean-François Brousseau <jfb@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove unused local variables from compat_futex_async

Reported-by: Jean-François Brousseau <jfb@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove unneeded syscall.h include from urcu-call-rcu-impl.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add ChangeLog file to Makefile.am

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add changelog, update version to 0.6.3

uatomic: fix warning about unused variable

Fix:

compat_arch_x86.c: In function '_compat_uatomic_set':
compat_arch_x86.c:104:16: warning: variable 'result' set but not used [-Wunused-but-set-variable]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

uatomic: fix i386 support

Fix:

* Incorrect prototype for uatomic_and and uatomic_or in i386
  compatibility code.
* Missing $(COMPAT) code inclusion in wfq/lfq tests.
* Silence gcc warnings about compat code (branch volountarily causing a
  linker error, which can never return).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Update version to 0.6.2

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

uatomic generic: map uatomic_and/or to correct symbols

Leading underscore was missing.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix generic atomic ops and/or: add missing return

Fixes build on powerpc:

./urcu/uatomic/generic.h: In function '_uatomic_and':
./urcu/uatomic/generic.h:310:2: warning: 'return' with a value, in
function returning void
./urcu/uatomic/generic.h: In function '_uatomic_or':
./urcu/uatomic/generic.h:374:2: warning: 'return' with a value, in
function returning void

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix test warning

Patch from:
https://build.opensuse.org/package/view_file?file=liburcu0-cleanup.patch&package=liburcu0&project=devel%3Atools%3Alttng&srcmd5=fa3ab9fae0401b4c0f73a9cf474eea16

fixes a warning in the liburcu tests.

Reported-by: Yannick Brosseau <yannick.brosseau@polymtl.ca>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add missing headers into tarball, version 0.6.1

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Update version to 0.6.0

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Futex: turn "int" into "int32_t" for portability

Even though int is 32-bit on all architectures supported by liburcu so
far, make it future-proof by uint a int32_t, which enforces the same
type width used by the system call in the kernel.

Using int32_t and not uint32_t to make comparison with 0 more
straightforward.

Reported-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add back uatomic_arch.h for slow deprecation process

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add back urcu-futex.h and urcu_ref.h for slow deprecation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add ldconfig step to README

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add a pkg-config file for the new liburcu-cds

Signed-off-by: Yannick Brosseau <yannick.brosseau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Consolidate _LIBADD and _DEPENDENCIES in Makefile.am

Signed-off-by: Alexandre Montplaisir <alexandre.montplaisir@polymtl.ca>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add urcu/cds.h placeholder for all CDS headers

Using CDS headers becomes as simple as:

 #include <urcu/cds.h>

and link with

 -lurcu-cds

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Move the version-info to the AM_LDFLAGS variable

Since all the lib builded in this directory use the same version
we can put this command in the global variable

Signed-off-by: Yannick Brosseau <yannick.brosseau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Installed headers should only include other headers with < >

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Rename urcu/urcu-futex.h to urcu/futex.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Rename urcu/urcu_ref.h to urcu/ref.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Headers: move uatomic_*.h to urcu/uatomic/*.h, rename uatomic_arch.h to uatomic.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Headers: move arch_*.h to urcu/arch/*.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Headers: move *-static.h headers to urcu/static/

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Install urcu/map/*.h into system

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Headers: move *-map.h headers to urcu/map/

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Add library version information

Following the guidelines from libtool
(http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.htm)
this patch add version information to the distributed libraries.
For the next release, the version will be 1:0:0.
It will need to be updated before each release.

Signed-off-by: Yannick Brosseau <yannick.brosseau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>