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* Update copyright dates with scripts/update-copyrightsJoseph Myers2023-01-061-1/+1
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* Use C11 atomics instead of atomic_and/orWilco Dijkstra2022-09-231-1/+1
| | | | | | | | | | Remove the 4 uses of atomic_and and atomic_or with atomic_fetch_and_acquire and atomic_fetch_or_acquire. This is preserves existing implied semantics, however relaxed MO on FUTEX_OWNER_DIED accesses may be correct. Passes regress on AArch64. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Add backoff mechanism to spinlock loopWangyang Guo2022-05-091-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When mutiple threads waiting for lock at the same time, once lock owner releases the lock, waiters will see lock available and all try to lock, which may cause an expensive CAS storm. Binary exponential backoff with random jitter is introduced. As try-lock attempt increases, there is more likely that a larger number threads compete for adaptive mutex lock, so increase wait time in exponential. A random jitter is also added to avoid synchronous try-lock from other threads. v2: Remove read-check before try-lock for performance. v3: 1. Restore read-check since it works well in some platform. 2. Make backoff arch dependent, and enable it for x86_64. 3. Limit max backoff to reduce latency in large critical section. v4: Fix strict-prototypes error in sysdeps/nptl/pthread_mutex_backoff.h v5: Commit log updated for regression in large critical section. Result of pthread-mutex-locks bench Test Platform: Xeon 8280L (2 socket, 112 CPUs in total) First Row: thread number First Col: critical section length Values: backoff vs upstream, time based, low is better non-critical-length: 1 1 2 4 8 16 32 64 112 140 0 0.99 0.58 0.52 0.49 0.43 0.44 0.46 0.52 0.54 1 0.98 0.43 0.56 0.50 0.44 0.45 0.50 0.56 0.57 2 0.99 0.41 0.57 0.51 0.45 0.47 0.48 0.60 0.61 4 0.99 0.45 0.59 0.53 0.48 0.49 0.52 0.64 0.65 8 1.00 0.66 0.71 0.63 0.56 0.59 0.66 0.72 0.71 16 0.97 0.78 0.91 0.73 0.67 0.70 0.79 0.80 0.80 32 0.95 1.17 0.98 0.87 0.82 0.86 0.89 0.90 0.90 64 0.96 0.95 1.01 1.01 0.98 1.00 1.03 0.99 0.99 128 0.99 1.01 1.01 1.17 1.08 1.12 1.02 0.97 1.02 non-critical-length: 32 1 2 4 8 16 32 64 112 140 0 1.03 0.97 0.75 0.65 0.58 0.58 0.56 0.70 0.70 1 0.94 0.95 0.76 0.65 0.58 0.58 0.61 0.71 0.72 2 0.97 0.96 0.77 0.66 0.58 0.59 0.62 0.74 0.74 4 0.99 0.96 0.78 0.66 0.60 0.61 0.66 0.76 0.77 8 0.99 0.99 0.84 0.70 0.64 0.66 0.71 0.80 0.80 16 0.98 0.97 0.95 0.76 0.70 0.73 0.81 0.85 0.84 32 1.04 1.12 1.04 0.89 0.82 0.86 0.93 0.91 0.91 64 0.99 1.15 1.07 1.00 0.99 1.01 1.05 0.99 0.99 128 1.00 1.21 1.20 1.22 1.25 1.31 1.12 1.10 0.99 non-critical-length: 128 1 2 4 8 16 32 64 112 140 0 1.02 1.00 0.99 0.67 0.61 0.61 0.61 0.74 0.73 1 0.95 0.99 1.00 0.68 0.61 0.60 0.60 0.74 0.74 2 1.00 1.04 1.00 0.68 0.59 0.61 0.65 0.76 0.76 4 1.00 0.96 0.98 0.70 0.63 0.63 0.67 0.78 0.77 8 1.01 1.02 0.89 0.73 0.65 0.67 0.71 0.81 0.80 16 0.99 0.96 0.96 0.79 0.71 0.73 0.80 0.84 0.84 32 0.99 0.95 1.05 0.89 0.84 0.85 0.94 0.92 0.91 64 1.00 0.99 1.16 1.04 1.00 1.02 1.06 0.99 0.99 128 1.00 1.06 0.98 1.14 1.39 1.26 1.08 1.02 0.98 There is regression in large critical section. But adaptive mutex is aimed for "quick" locks. Small critical section is more common when users choose to use adaptive pthread_mutex. Signed-off-by: Wangyang Guo <wangyang.guo@intel.com> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* nptl: Effectively skip CAS in spinlock loopJangwoong Kim2022-01-201-3/+2
| | | | | | | | | | | | | | | | The commit: "Add LLL_MUTEX_READ_LOCK [BZ #28537]" SHA1: d672a98a1af106bd68deb15576710cd61363f7a6 introduced LLL_MUTEX_READ_LOCK, to skip CAS in spinlock loop if atomic load fails. But, "continue" inside of do-while loop does not skip the evaluation of escape expression, thus CAS is not skipped. Replace do-while with while and skip LLL_MUTEX_TRYLOCK if LLL_MUTEX_READ_LOCK fails. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* Update copyright dates with scripts/update-copyrightsPaul Eggert2022-01-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
* Move assignment out of the CAS conditionH.J. Lu2021-11-151-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | Update commit 49302b8fdf9103b6fc0a398678668a22fa19574c Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Nov 11 06:54:01 2021 -0800 Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537] Replace boolean CAS with value CAS to avoid the extra load. and commit 0b82747dc48d5bf0871bdc6da8cb6eec1256355f Author: H.J. Lu <hjl.tools@gmail.com> Date: Thu Nov 11 06:31:51 2021 -0800 Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537] Replace boolean CAS with value CAS to avoid the extra load. by moving assignment out of the CAS condition.
* Add LLL_MUTEX_READ_LOCK [BZ #28537]H.J. Lu2021-11-121-0/+7
| | | | | | | | | | | | | | | | CAS instruction is expensive. From the x86 CPU's point of view, getting a cache line for writing is more expensive than reading. See Appendix A.2 Spinlock in: https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/xeon-lock-scaling-analysis-paper.pdf The full compare and swap will grab the cache line exclusive and cause excessive cache line bouncing. Add LLL_MUTEX_READ_LOCK to do an atomic load and skip CAS in spinlock loop if compare may fail to reduce cache line bouncing on contended locks. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
* Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537]H.J. Lu2021-11-121-5/+5
| | | | | | Replace boolean CAS with value CAS to avoid the extra load. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
* nptl: Use FUTEX_LOCK_PI2 when availableAdhemerval Zanella2021-10-011-1/+2
| | | | | | | | | | | This patch uses the new futex PI operation provided by Linux v5.14 when it is required. The futex_lock_pi64() is moved to futex-internal.c (since it used on two different places and its code size might be large depending of the kernel configuration) and clockid is added as an argument. Co-authored-by: Kurt Kanzenbach <kurt@linutronix.de>
* Remove "Contributed by" linesSiddhesh Poyarekar2021-09-031-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* nptl: Remove GLIBC_2.34 versions of __pthread_mutex_lock, __pthread_mutex_unlockFlorian Weimer2021-07-071-2/+3
| | | | | | | | Now that there are no internal users anymore, these new symbol versions can be removed from the public ABI. The compatibility symbols remain. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Move core mutex functions into libcFlorian Weimer2021-04-211-5/+17
| | | | | | | | | | | | | | This is complicated because of a second compilation of nptl/pthread_mutex_lock.c via nptl/pthread_mutex_cond_lock.c. PTHREAD_MUTEX_VERSIONS is introduced to suppress symbol versions in that case. The symbols __pthread_mutex_lock, __pthread_mutex_unlock, __pthread_mutex_init, __pthread_mutex_destroy, pthread_mutex_lock, pthread_mutex_unlock, pthread_mutex_init, pthread_mutex_destroy have been moved using scripts/move-symbol-to-libc.py. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: pthread_mutex_lock, pthread_mutex_unock single-threaded optimizationFlorian Weimer2021-04-211-3/+22
| | | | | | | | | This is optimization is similar in spirit to the SINGLE_THREAD_P check in the malloc implementation. Doing this in generic code allows us to prioritize those cases which are likely to occur in single-threaded programs (normal and recursive mutexes). Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Move elision implementations into libcFlorian Weimer2021-02-231-14/+1
| | | | | | | | | | | | | | | | | | The elision interfaces are closely aligned between the targets that implement them, so declare them in the generic <lowlevellock.h> file. Empty .c stubs are provided, so that fewer makefile updates under sysdeps are needed. Also simplify initialization via __libc_early_init. The symbols __lll_clocklock_elision, __lll_lock_elision, __lll_trylock_elision, __lll_unlock_elision, __pthread_force_elision move into libc. For the time being, non-hidden references are used from libpthread to access them, but once that part of libpthread is moved into libc, hidden symbols will be used again. (Hidden references seem desirable to reduce the likelihood of transactions aborts.)
* Update copyright dates with scripts/update-copyrightsPaul Eggert2021-01-021-1/+1
| | | | | | | | | | | | | | | | I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 6694 files FOO. I then removed trailing white space from benchtests/bench-pthread-locks.c and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this diagnostic from Savannah: remote: *** pre-commit check failed ... remote: *** error: lines with trailing whitespace found remote: error: hook declined to update refs/heads/master
* nptl: Replace lll_futex_{timed_}wait by futex-internal.hAdhemerval Zanella2020-11-251-4/+5
| | | | | | | | | The idea is to make NPTL implementation to use on the functions provided by futex-internal.h. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Lukasz Majewski <lukma@denx.de>
* nptl: Replace lll_timedwait with __futex_abstimed_wait64Adhemerval Zanella2020-11-251-2/+2
| | | | | | Checked with x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Lukasz Majewski <lukma@denx.de>
* nptl: Remove unused internal futex functionsAdhemerval Zanella2020-11-251-2/+1
| | | | | | | | | | The __futex_abstimed_wait usage was remove with 3102e28bd11 and the __futex_abstimed_wait_cancelable by 323592fdc92 and b8d3e8fbaac. The futex_lock_pi can be replaced by a futex_lock_pi64. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Lukasz Majewski <lukma@denx.de>
* nptl: Eliminate <smp.h> and __is_smpFlorian Weimer2020-11-131-3/+0
| | | | | | | | | | | Most systems are SMP, so optimizing for the UP case is no longer approriate. A dynamic check based on the kernel identification has been only implemented for i386 anyway. To disable adaptive mutexes on sh, define DEFAULT_ADAPTIVE_COUNT as zero for this architecture. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Update copyright dates with scripts/update-copyrights.Joseph Myers2020-01-011-1/+1
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* Refactor PI mutexes internal definitionsAdhemerval Zanella2019-10-311-16/+8
| | | | | | | | | | This patch adds the generic futex_lock_pi and futex_unlock_pi to wrap around the syscall machinery required to issue the syscall calls. It simplifies a bit the futex code required to implement PI mutexes. No function changes, checked on x86_64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* nptl: Replace non cancellable pause/nanosleep with futexAdhemerval Zanella2019-10-311-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | To help y2038 work avoid duplicate all the logic of nanosleep on non cancellable version, the patch replace it with a new futex operation, lll_timedwait. The changes are: - Add a expected value for __lll_clocklock_wait, so it can be used to wait for generic values. - Remove its internal atomic operation and move the logic to __lll_clocklock. It makes __lll_clocklock_wait even more generic and __lll_clocklock slight faster on fast-path (since it won't require a function call anymore). - Add lll_timedwait, which uses __lll_clocklock_wait, to replace both __pause_nocancel and __nanosleep_nocancel. It also allows remove the sparc32 __lll_clocklock_wait implementation (since it is similar to the generic one). Checked on x86_64-linux-gnu, sparcv9-linux-gnu, and i686-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* Prefer https to http for gnu.org and fsf.org URLsPaul Eggert2019-09-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
* Update copyright dates with scripts/update-copyrights.Joseph Myers2019-01-011-1/+1
| | | | | | | * All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
* Mutex: Add pthread mutex tunablesKemi Wang2018-12-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch does not have any functionality change, we only provide a spin count tunes for pthread adaptive spin mutex. The tunable glibc.pthread.mutex_spin_count tunes can be used by system administrator to squeeze system performance according to different hardware capabilities and workload characteristics. The maximum value of spin count is limited to 32767 to avoid the overflow of mutex->__data.__spins variable with the possible type of short in pthread_mutex_lock (). The default value of spin count is set to 100 with the reference to the previous number of times of spinning via trylock. This value would be architecture-specific and can be tuned with kinds of benchmarks to fit most cases in future. I would extend my appreciation sincerely to H.J.Lu for his help to refine this patch series. * manual/tunables.texi (POSIX Thread Tunables): New node. * nptl/Makefile (libpthread-routines): Add pthread_mutex_conf. * nptl/nptl-init.c: Include pthread_mutex_conf.h (__pthread_initialize_minimal_internal) [HAVE_TUNABLES]: Call __pthread_tunables_init. * nptl/pthreadP.h (MAX_ADAPTIVE_COUNT): Remove. (max_adaptive_count): Define. * nptl/pthread_mutex_conf.c: New file. * nptl/pthread_mutex_conf.h: New file. * sysdeps/generic/adaptive_spin_count.h: New file. * sysdeps/nptl/dl-tunables.list: New file. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock): Use max_adaptive_count () not MAX_ADAPTIVE_COUNT. * nptl/pthread_mutex_timedlock.c (__pthrad_mutex_timedlock): Likewise. Suggested-by: Andi Kleen <andi.kleen@intel.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com> Signed-off-by: Kemi.wang <kemi.wang@intel.com>
* Fix race in pthread_mutex_lock while promoting to PTHREAD_MUTEX_ELISION_NP ↵Stefan Liebler2018-10-171-7/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BZ #23275] The race leads either to pthread_mutex_destroy returning EBUSY or triggering an assertion (See description in bugzilla). This patch is fixing the race by ensuring that the elision path is used in all cases if elision is enabled by the GLIBC_TUNABLES framework. The __kind variable in struct __pthread_mutex_s is accessed concurrently. Therefore we are now using the atomic macros. The new testcase tst-mutex10 is triggering the race on s390x and intel. Presumably also on power, but I don't have access to a power machine with lock-elision. At least the code for power is the same as on the other two architectures. ChangeLog: [BZ #23275] * nptl/tst-mutex10.c: New File. * nptl/Makefile (tests): Add tst-mutex10. (tst-mutex10-ENV): New variable. * sysdeps/unix/sysv/linux/s390/force-elision.h: (FORCE_ELISION): Ensure that elision path is used if elision is available. * sysdeps/unix/sysv/linux/powerpc/force-elision.h (FORCE_ELISION): Likewise. * sysdeps/unix/sysv/linux/x86/force-elision.h: (FORCE_ELISION): Likewise. * nptl/pthreadP.h (PTHREAD_MUTEX_TYPE, PTHREAD_MUTEX_TYPE_ELISION) (PTHREAD_MUTEX_PSHARED): Use atomic_load_relaxed. * nptl/pthread_mutex_consistent.c (pthread_mutex_consistent): Likewise. * nptl/pthread_mutex_getprioceiling.c (pthread_mutex_getprioceiling): Likewise. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full) (__pthread_mutex_cond_lock_adjust): Likewise. * nptl/pthread_mutex_setprioceiling.c (pthread_mutex_setprioceiling): Likewise. * nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock): Likewise. * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Likewise. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise. * sysdeps/nptl/bits/thread-shared-types.h (struct __pthread_mutex_s): Add comments. * nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy): Use atomic_load_relaxed and atomic_store_relaxed. * nptl/pthread_mutex_init.c (__pthread_mutex_init): Use atomic_store_relaxed.
* Update copyright dates with scripts/update-copyrights.Joseph Myers2018-01-011-1/+1
| | | | | | | * All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
* nptl: Change tst-typesizes to _Static_assertAdhemerval Zanella2017-11-071-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of rely on runtime check to assure correct pthread types size a better strategy would use _Static_assert to trigger an error on build time (and thus allowing to check to potentially ABI breakage on cross-compiling make check). This patch moves nptl/tst-typesizes.c to libpthread build time on each specific initialization routine and also remove some runtime redundant asserts for the same type sizes. Checked on x86_64-linux-gnu and with a build check for all affected ABIs (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf, hppa-linux-gnu, i686-linux-gnu, ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu, mips64-linux-gnu, mips64-n32-linux-gnu, mips-linux-gnu, powerpc64le-linux-gnu, powerpc-linux-gnu, s390-linux-gnu, s390x-linux-gnu, sh4-linux-gnu, sparc64-linux-gnu, sparcv9-linux-gnu, tilegx-linux-gnu, tilegx-linux-gnu-x32, tilepro-linux-gnu, x86_64-linux-gnu, and x86_64-linux-x32). * nptl/pthreadP.h (ASSERT_TYPE_SIZE, ASSERT_PTHREAD_INTERNAL_SIZE): New macros. * nptl/pthread_attr_init.c (__pthread_mutex_init): Add build time checks for expected input type size. * nptl/pthread_barrier_init.c (__pthread_barrier_init): Likewise. * nptl/pthread_barrierattr_init.c (pthread_barrierattr_init): Likewise. * nptl/pthread_cond_init.c (__pthread_cond_init): Likewise. * nptl/pthread_condattr_init.c (__pthread_condattr_init): Likewise. * nptl/pthread_mutex_init.c (__pthread_mutex_init): Likewise. * nptl/pthread_mutexattr_init.c (__pthread_mutexattr_init): Likewise. * nptl/pthread_rwlock_init.c (__pthread_rwlock_init): Likewise. * nptl/pthread_rwlockattr_init.c (pthread_rwlockattr_init): Likewise. * nptl/sem_init.c (__new_sem_init, __old_sem_init): Likewise * nptl/pthread_attr_destroy.c (__pthread_attr_destroy): Remove superflous runtime assert check. * nptl/pthread_attr_getaffinity.c (__pthread_attr_getaffinity_new): Likewise. * nptl/pthread_attr_getdetachstate.c (__pthread_attr_getdetachstate): Likewise. * nptl/pthread_attr_getguardsize.c (pthread_attr_getguardsize): Likewise. * nptl/pthread_attr_getinheritsched.c (__pthread_attr_getinheritsched): Likewise. * nptl/pthread_attr_getschedparam.c (__pthread_attr_getschedparam): Likewise. * nptl/pthread_attr_getschedpolicy.c (__pthread_attr_getschedpolicy): Likewise. * nptl/pthread_attr_getscope.c (__pthread_attr_getscope): Likewise. * nptl/pthread_attr_getstack.c (__pthread_attr_getstack): Likewise. * nptl/pthread_attr_getstackaddr.c (__pthread_attr_getstackaddr): Likewise. * nptl/pthread_attr_getstacksize.c (__pthread_attr_getstacksize): Likewise. * nptl/pthread_attr_setaffinity.c (__pthread_attr_setaffinity_new): Likewise. * nptl/pthread_attr_setdetachstate.c (__pthread_attr_setdetachstate): Likewise. * nptl/pthread_attr_setguardsize.c (pthread_attr_setguardsize): Likewise. * nptl/pthread_attr_setinheritsched.c (__pthread_attr_setinheritsched): Likewise. * nptl/pthread_attr_setschedparam.c (__pthread_attr_setschedparam): Likewise. * nptl/pthread_attr_setschedpolicy.c (__pthread_attr_setschedpolicy): Likewise. * nptl/pthread_attr_setscope.c (__pthread_attr_setscope): Likewise. * nptl/pthread_attr_setstack.c (__pthread_attr_setstack, __old_pthread_attr_setstack): Likewise. * nptl/pthread_attr_setstackaddr.c (__pthread_attr_setstackaddr): Likewise. * nptl/pthread_attr_setstacksize.c (__pthread_attr_setstacksize): Likewise. * nptl/pthread_getattr_default_np.c (pthread_getattr_default_np): Likewise. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock): Likewise. * nptl/pthread_setattr_default_np.c (pthread_setattr_default_np): Likewise. * nptl/tst-typesizes.c: Remove file. Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Remove internal_function attributeFlorian Weimer2017-08-311-1/+0
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* Consolidate non cancellable pause callAdhemerval Zanella2017-08-221-1/+1
| | | | | | | | | | | | | | | | | | This patch consolidates all the non cancellable pause calls to use the __pause_nocancel identifier. For non cancellable targets it will be just a macro to call the default respective symbol while on Linux will be a internal one. Checked on x86_64-linux-gnu, x86_64-linux-gnu-x32, and i686-linux-gnu. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Replace pause_not_cancel with __pause_nocancel. * sysdeps/generic/not-cancel.h (pause_not_cancel): Remove macro. (__pause_nocancel): New macro. * sysdeps/unix/sysv/linux/not-cancel.h (pause_not_cancel): Remove macro. (__pause_nocancel): New prototype. * sysdeps/unix/sysv/linux/pause.c (__pause_nocancel): New function.
* mutex: Fix robust mutex lock acquire (Bug 21778)Carlos O'Donell2017-07-291-5/+8
| | | | | | | | | | | | | 65810f0ef05e8c9e333f17a44e77808b163ca298 fixed a robust mutex bug but introduced BZ 21778: if the CAS used to try to acquire a lock fails, the expected value is not updated, which breaks other cases in the loce acquisition loop. The fix is to simply update the expected value with the value returned by the CAS, which ensures that behavior is as if the first case with the CAS never happened (if the CAS fails). This is a regression introduced in the last release. Tested on x86_64, i686, ppc64, ppc64le, s390x, aarch64, armv7hl.
* Clean pthread functions namespaces for C11 threadsAdhemerval Zanella2017-06-231-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds internal definition (through {libc_}hidden_{proto,def}) and also change some strong to weak alias for symbols that might be used by C11 threads implementations. The patchset should not change libc/libpthread functional, although object changes are expected (since now internal symbols are used instead) and final exported symbols through GLIBC_PRIVATE is also expanded (to cover libpthread usage of __mmap{64}, __munmap, __mprotect). Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu, powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu, tile{pro,gx}-linux-gnu, and x86_64-linux-gnu). * include/sched.h (__sched_get_priority_max): Add libc hidden proto. (__sched_get_prioriry_min): Likewise. * include/sys/mman.h (__mmap): Likewise. (__mmap64): Likewise. (__munmap): Likewise. (__mprotect): Likewise. * include/termios.h (__tcsetattr): Likewise. * include/time.h (__nanosleep): Use hidden_proto instead of libc_hidden_proto. * posix/nanosleep.c (__nanosleep): Likewise. * misc/Versions (libc): Export __mmap, __munmap, __mprotect, __sched_get_priority_min, and __sched_get_priority_max under GLIBC_PRIVATE. * nptl/allocatestack.c (__free_stacks): Use internal definition for libc symbols. (change_stack_perm): Likewise. (allocate_stack): Likewise. * sysdeps/posix/gethostname.c: Likewise. * nptl/tpp.c (__init_sched_fifo_prio): Likewise. * sysdeps/unix/sysv/linux/i386/smp.h (is_smp_system): Likewise. * sysdeps/unix/sysv/linux/powerpc/ioctl.c (__ioctl): Likewise. * nptl/pthreadP.h (__pthread_mutex_timedlock): Add definition. (__pthread_key_delete): Likewise. (__pthread_detach): Likewise. (__pthread_cancel): Likewise. (__pthread_mutex_trylock): Likewise. (__pthread_mutexattr_init): Likewise. (__pthread_mutexattr_settype): Likewise. * nptl/pthread_cancel.c (pthread_cancel): Change to internal name and create alias for exported one. * nptl/pthread_join.c (pthread_join): Likewise. * nptl/pthread_detach.c (pthread_detach): Likewise. * nptl/pthread_key_delete.c (pthread_key_delete): Likewise. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise. * nptl/pthread_create.c: Change static requirements for pthread symbols. * nptl/pthread_equal.c (__pthread_equal): Change strong alias to weak for internal definition. * nptl/pthread_exit.c (__pthread_exit): Likewise. * nptl/pthread_getspecific.c (__pthread_getspecific): Likewise. * nptl/pthread_key_create.c (__pthread_key_create): Likewise. * nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy): Likewise. * nptl/pthread_mutex_init.c (__pthread_mutex_init): Likewise. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock): Likewise. * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Likewise. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock): Likewise. * nptl/pthread_mutexattr_init.c (__pthread_mutexattr_init): Likwise. * nptl/pthread_mutexattr_settype.c (__pthread_mutexattr_settype): Likewise. * nptl/pthread_self.c (__pthread_self): Likewise. * nptl/pthread_setspecific.c (__pthread_setspecific): Likewise. * sysdeps/unix/sysv/linux/tcsetattr.c (tcsetattr): Likewise. * misc/mmap.c (__mmap): Add internal symbol definition. * misc/mmap.c (__mmap64): Likewise. * sysdeps/unix/sysv/linux/mmap.c (__mmap): Likewise. * sysdeps/unix/sysv/linux/mmap64.c (__mmap): Likewise. (__mmap64): Likewise. * sysdeps/unix/sysv/linux/i386/Versions (libc) [GLIBC_PRIVATE): Add __uname.
* Add compiler barriers around modifications of the robust mutex list.Torvald Riegel2017-01-131-4/+44
| | | | | | | | | | | | | | | | | | | Any changes to the per-thread list of robust mutexes currently acquired as well as the pending-operations entry are not simply sequential code but basically concurrent with any actions taken by the kernel when it tries to clean up after a crash. This is not quite like multi-thread concurrency but more like signal-handler concurrency. This patch fixes latent bugs by adding compiler barriers where necessary so that it is ensured that the kernel crash handling sees consistent data. This is meant to be easy to backport, so we do not use C11-style signal fences yet. * nptl/descr.h (ENQUEUE_MUTEX_BOTH, DEQUEUE_MUTEX): Add compiler barriers and comments. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Likewise. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
* robust mutexes: Fix broken x86 assembly by removing itTorvald Riegel2017-01-131-23/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | lll_robust_unlock on i386 and x86_64 first sets the futex word to FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the futex word to 0. If the thread is killed between these steps, then the futex word will be FUTEX_WAITERS|0, and the kernel (at least current upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is not equal to the TID of the crashed thread. The lll_robust_lock assembly code on i386 and x86_64 is not prepared to deal with this case because the fastpath tries to only CAS 0 to TID and not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0 to TID or the futex_word has the FUTEX_OWNER_DIED bit set. This issue is fixed by removing the custom x86 assembly code and using the generic C code instead. However, instead of adding more duplicate code to the custom x86 lowlevellock.h, the code of the lll_robust* functions is inlined into the single call sites that exist for each of these functions in the pthread_mutex_* functions. The robust mutex paths in the latter have been slightly reorganized to make them simpler. This patch is meant to be easy to backport, so C11-style atomics are not used. [BZ #20985] * nptl/Makefile: Adapt. * nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. * nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. (__pthread_mutex_lock_full): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise. * sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * nptl/lowlevelrobustlock.c: Remove file. * nptl/lowlevelrobustlock.sym: Likewise. * sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise. * sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.
* Update copyright dates with scripts/update-copyrights.Joseph Myers2017-01-011-1/+1
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* Robust mutexes: Fix lost wake-up.Torvald Riegel2016-12-191-2/+13
| | | | | | | | | | | | | | | | | | | | | | Assume that Thread 1 waits to acquire a robust mutex using futexes to block (and thus sets the FUTEX_WAITERS flag), and is unblocked when this mutex is released. If Thread 2 concurrently acquires the lock and is killed, Thread 1 can recover from the died owner but fail to restore the FUTEX_WAITERS flag. This can lead to a Thread 3 that also blocked using futexes at the same time as Thread 1 to not get woken up because FUTEX_WAITERS is not set anymore. The fix for this is to ensure that we continue to preserve the FUTEX_WAITERS flag whenever we may have set it or shared it with another thread. This is the same requirement as in the algorithm for normal mutexes, only that the robust mutexes need additional handling for died owners and thus preserving the FUTEX_WAITERS flag cannot be done just in the futex slowpath code. [BZ #20973] * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Fix lost wake-up in robust mutexes. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise.
* Update copyright dates with scripts/update-copyrights.Joseph Myers2016-01-041-1/+1
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* Convert 113 more function definitions to prototype style (files with ↵Joseph Myers2015-10-201-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | assertions). This mostly automatically-generated patch converts 113 function definitions in glibc from old-style K&R to prototype-style. Following my other recent such patches, this one deals with the case of function definitions in files that either contain assertions or where grep suggested they might contain assertions - and thus where it isn't possible to use a simple object code comparison as a sanity check on the correctness of the patch, because line numbers are changed. A few such automatically-generated changes needed to be supplemented by manual changes for the result to compile. openat64 had a prototype declaration with "..." but an old-style definition in sysdeps/unix/sysv/linux/dl-openat64.c, and "..." needed adding to the generated prototype in the definition (I've filed <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68024> for diagnosing such cases in GCC; the old state was undefined behavior not requiring a diagnostic, but one seems a good idea). In addition, as Florian has noted regparm attribute mismatches between declaration and definition are only diagnosed for prototype definitions, and five functions needed internal_function added to their definitions (in the case of __pthread_mutex_cond_lock, via the macro definition of __pthread_mutex_lock) to compile on i386. After this patch is in, remaining old-style definitions are probably most readily fixed manually before we can turn on -Wold-style-definition for all builds. Tested for x86_64 and x86 (testsuite). * crypt/md5-crypt.c (__md5_crypt_r): Convert to prototype-style function definition. * crypt/sha256-crypt.c (__sha256_crypt_r): Likewise. * crypt/sha512-crypt.c (__sha512_crypt_r): Likewise. * debug/backtracesyms.c (__backtrace_symbols): Likewise. * elf/dl-minimal.c (_itoa): Likewise. * hurd/hurdmalloc.c (malloc): Likewise. (free): Likewise. (realloc): Likewise. * inet/inet6_option.c (inet6_option_space): Likewise. (inet6_option_init): Likewise. (inet6_option_append): Likewise. (inet6_option_alloc): Likewise. (inet6_option_next): Likewise. (inet6_option_find): Likewise. * io/ftw.c (FTW_NAME): Likewise. (NFTW_NAME): Likewise. (NFTW_NEW_NAME): Likewise. (NFTW_OLD_NAME): Likewise. * libio/iofwide.c (_IO_fwide): Likewise. * libio/strops.c (_IO_str_init_static_internal): Likewise. (_IO_str_init_static): Likewise. (_IO_str_init_readonly): Likewise. (_IO_str_overflow): Likewise. (_IO_str_underflow): Likewise. (_IO_str_count): Likewise. (_IO_str_seekoff): Likewise. (_IO_str_pbackfail): Likewise. (_IO_str_finish): Likewise. * libio/wstrops.c (_IO_wstr_init_static): Likewise. (_IO_wstr_overflow): Likewise. (_IO_wstr_underflow): Likewise. (_IO_wstr_count): Likewise. (_IO_wstr_seekoff): Likewise. (_IO_wstr_pbackfail): Likewise. (_IO_wstr_finish): Likewise. * locale/programs/localedef.c (normalize_codeset): Likewise. * locale/programs/locarchive.c (add_locale_to_archive): Likewise. (add_locales_to_archive): Likewise. (delete_locales_from_archive): Likewise. * malloc/malloc.c (__libc_mallinfo): Likewise. * math/gen-auto-libm-tests.c (init_fp_formats): Likewise. * misc/tsearch.c (__tfind): Likewise. * nptl/pthread_attr_destroy.c (__pthread_attr_destroy): Likewise. * nptl/pthread_attr_getdetachstate.c (__pthread_attr_getdetachstate): Likewise. * nptl/pthread_attr_getguardsize.c (pthread_attr_getguardsize): Likewise. * nptl/pthread_attr_getinheritsched.c (__pthread_attr_getinheritsched): Likewise. * nptl/pthread_attr_getschedparam.c (__pthread_attr_getschedparam): Likewise. * nptl/pthread_attr_getschedpolicy.c (__pthread_attr_getschedpolicy): Likewise. * nptl/pthread_attr_getscope.c (__pthread_attr_getscope): Likewise. * nptl/pthread_attr_getstack.c (__pthread_attr_getstack): Likewise. * nptl/pthread_attr_getstackaddr.c (__pthread_attr_getstackaddr): Likewise. * nptl/pthread_attr_getstacksize.c (__pthread_attr_getstacksize): Likewise. * nptl/pthread_attr_init.c (__pthread_attr_init_2_1): Likewise. (__pthread_attr_init_2_0): Likewise. * nptl/pthread_attr_setdetachstate.c (__pthread_attr_setdetachstate): Likewise. * nptl/pthread_attr_setguardsize.c (pthread_attr_setguardsize): Likewise. * nptl/pthread_attr_setinheritsched.c (__pthread_attr_setinheritsched): Likewise. * nptl/pthread_attr_setschedparam.c (__pthread_attr_setschedparam): Likewise. * nptl/pthread_attr_setschedpolicy.c (__pthread_attr_setschedpolicy): Likewise. * nptl/pthread_attr_setscope.c (__pthread_attr_setscope): Likewise. * nptl/pthread_attr_setstack.c (__pthread_attr_setstack): Likewise. * nptl/pthread_attr_setstackaddr.c (__pthread_attr_setstackaddr): Likewise. * nptl/pthread_attr_setstacksize.c (__pthread_attr_setstacksize): Likewise. * nptl/pthread_condattr_setclock.c (pthread_condattr_setclock): Likewise. * nptl/pthread_create.c (__find_in_stack_list): Likewise. * nptl/pthread_getattr_np.c (pthread_getattr_np): Likewise. * nptl/pthread_mutex_cond_lock.c (__pthread_mutex_lock): Define to use internal_function. * nptl/pthread_mutex_init.c (__pthread_mutex_init): Convert to prototype-style function definition. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock): Likewise. (__pthread_mutex_cond_lock_adjust): Likewise. Use internal_function. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Convert to prototype-style function definition. * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Likewise. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_usercnt): Likewise. (__pthread_mutex_unlock): Likewise. * nptl_db/td_ta_clear_event.c (td_ta_clear_event): Likewise. * nptl_db/td_ta_set_event.c (td_ta_set_event): Likewise. * nptl_db/td_thr_clear_event.c (td_thr_clear_event): Likewise. * nptl_db/td_thr_event_enable.c (td_thr_event_enable): Likewise. * nptl_db/td_thr_set_event.c (td_thr_set_event): Likewise. * nss/makedb.c (process_input): Likewise. * posix/fnmatch.c (__strchrnul): Likewise. (__wcschrnul): Likewise. (fnmatch): Likewise. * posix/fnmatch_loop.c (FCT): Likewise. * posix/glob.c (globfree): Likewise. (__glob_pattern_type): Likewise. (__glob_pattern_p): Likewise. * posix/regcomp.c (re_compile_pattern): Likewise. (re_set_syntax): Likewise. (re_compile_fastmap): Likewise. (regcomp): Likewise. (regerror): Likewise. (regfree): Likewise. * posix/regexec.c (regexec): Likewise. (re_match): Likewise. (re_search): Likewise. (re_match_2): Likewise. (re_search_2): Likewise. (re_search_stub): Likewise. Use internal_function (re_copy_regs): Likewise. (re_set_registers): Convert to prototype-style function definition. (prune_impossible_nodes): Likewise. Use internal_function. * resolv/inet_net_pton.c (inet_net_pton): Convert to prototype-style function definition. (inet_net_pton_ipv4): Likewise. * stdlib/strtod_l.c (____STRTOF_INTERNAL): Likewise. * sysdeps/pthread/aio_cancel.c (aio_cancel): Likewise. * sysdeps/pthread/aio_suspend.c (aio_suspend): Likewise. * sysdeps/pthread/timer_delete.c (timer_delete): Likewise. * sysdeps/unix/sysv/linux/dl-openat64.c (openat64): Likewise. Make variadic. * time/strptime_l.c (localtime_r): Convert to prototype-style function definition. * wcsmbs/mbsnrtowcs.c (__mbsnrtowcs): Likewise. * wcsmbs/mbsrtowcs_l.c (__mbsrtowcs_l): Likewise. * wcsmbs/wcsnrtombs.c (__wcsnrtombs): Likewise. * wcsmbs/wcsrtombs.c (__wcsrtombs): Likewise.
* Clean up BUSY_WAIT_NOP and atomic_delay.Torvald Riegel2015-06-301-4/+2
| | | | | | | | | This patch combines BUSY_WAIT_NOP and atomic_delay into a new atomic_spin_nop function and adjusts all clients. The new function is put into atomic.h because what is best done in a spin loop is architecture-specific, and atomics must be used for spinning. The function name is meant to tell users that this has no effect on synchronization semantics but is a performance aid for spinning.
* Update copyright dates with scripts/update-copyrights.Joseph Myers2015-01-021-1/+1
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* NPTL: Conditionalize direct futex syscall uses.Roland McGrath2014-10-171-4/+9
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* Add missing #include for MIN/MAX users.Roland McGrath2014-07-011-0/+1
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* Use glibc_likely instead __builtin_expect.Ondřej Bílka2014-02-101-10/+10
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* Update copyright notices with scripts/update-copyrightsAllan McRae2014-01-011-1/+1
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* Clean up whitespace in lock elision patches.Dominik Vogt2013-07-191-1/+1
| | | | Signed-off-by: Carlos O'Donell <carlos@redhat.com>
* Add elision to pthread_mutex_{try,timed,un}lockAndi Kleen2013-07-021-10/+43
| | | | | | | | | | | | | | | | | | | | | | | Add elision paths to the basic mutex locks. The normal path has a check for RTM and upgrades the lock to RTM when available. Trylocks cannot automatically upgrade, so they check for elision every time. We use a 4 byte value in the mutex to store the lock elision adaptation state. This is separate from the adaptive spin state and uses a separate field. Condition variables currently do not support elision. Recursive mutexes and condition variables may be supported at some point, but are not in the current implementation. Also "trylock" will not automatically enable elision unless some other lock call has been already called on the lock. This version does not use IFUNC, so it means every lock has one additional check for elision. Benchmarking showed the overhead to be negligible.
* Update copyright notices with scripts/update-copyrights.Joseph Myers2013-01-021-1/+1
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* Remove use of INTDEF/INTUSE in nptlAndreas Schwab2012-05-301-1/+1
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* Add systemtap static probe points in generic and x86_64 pthread code.Roland McGrath2012-05-251-1/+9
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* Replace FSF snail mail address with URLs.Paul Eggert2012-02-091-3/+2
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