From patchwork Fri Oct 17 21:32:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roland McGrath X-Patchwork-Id: 3278 Received: (qmail 17647 invoked by alias); 17 Oct 2014 21:32:37 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 17634 invoked by uid 89); 17 Oct 2014 21:32:36 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: topped-with-meat.com MIME-Version: 1.0 From: Roland McGrath To: "GNU C. Library" Subject: [COMMITTED PATCH] NPTL: Conditionalize direct futex syscall uses. Message-Id: <20141017213233.1A7C42C2452@topped-with-meat.com> Date: Fri, 17 Oct 2014 14:32:33 -0700 (PDT) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.1 cv=SvUDtp+0 c=1 sm=1 tr=0 a=WkljmVdYkabdwxfqvArNOQ==:117 a=14OXPxybAAAA:8 a=Z6MIti7PxpgA:10 a=kj9zAlcOel0A:10 a=hOe2yjtxAAAA:8 a=iPA9J1MZMajzMaf26E4A:9 a=CjuIK1q_8ugA:10 This has no material effect on Linux configurations. Thanks, Roland * nptl/nptl-init.c (__pthread_initialize_minimal_internal): Conditionalize FUTEX_PRIVATE_FLAG and FUTEX_CLOCK_REALTIME probes on [__NR_futex]. * nptl/pthread_mutex_init.c (prio_inherit_missing): New function, broken out of ... (__pthread_mutex_init): ... here. Call it. * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Conditionalize PI cases on [__NR_futex]. * 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. --- a/nptl/nptl-init.c +++ b/nptl/nptl-init.c @@ -329,7 +329,8 @@ __pthread_initialize_minimal_internal (void) #endif set_robust_list_not_avail (); -#ifndef __ASSUME_PRIVATE_FUTEX +#ifdef __NR_futex +# ifndef __ASSUME_PRIVATE_FUTEX /* Private futexes are always used (at least internally) so that doing the test once this early is beneficial. */ { @@ -345,8 +346,8 @@ __pthread_initialize_minimal_internal (void) know the former are not supported. This also means we know the kernel will return ENOSYS for unknown operations. */ if (THREAD_GETMEM (pd, header.private_futex) != 0) -#endif -#ifndef __ASSUME_FUTEX_CLOCK_REALTIME +# endif +# ifndef __ASSUME_FUTEX_CLOCK_REALTIME { int word = 0; /* NB: the syscall actually takes six parameters. The last is the @@ -361,6 +362,7 @@ __pthread_initialize_minimal_internal (void) if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS) __set_futex_clock_realtime (); } +# endif #endif /* Set initial thread's stack block from 0 up to __libc_stack_end. --- a/nptl/pthread_mutex_init.c +++ b/nptl/pthread_mutex_init.c @@ -18,6 +18,7 @@ #include #include +#include #include #include #include "pthreadP.h" @@ -31,10 +32,26 @@ static const struct pthread_mutexattr default_mutexattr = }; -#ifndef __ASSUME_FUTEX_LOCK_PI -static int tpi_supported; +static bool +prio_inherit_missing (void) +{ +#ifdef __NR_futex +# ifndef __ASSUME_FUTEX_LOCK_PI + static int tpi_supported; + if (__glibc_unlikely (tpi_supported == 0)) + { + int lock = 0; + INTERNAL_SYSCALL_DECL (err); + int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI, 0, 0); + assert (INTERNAL_SYSCALL_ERROR_P (ret, err)); + tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1; + } + return __glibc_unlikely (tpi_supported < 0); +# endif + return false; #endif - + return true; +} int __pthread_mutex_init (mutex, mutexattr) @@ -58,19 +75,8 @@ __pthread_mutex_init (mutex, mutexattr) break; case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT: -#ifndef __ASSUME_FUTEX_LOCK_PI - if (__glibc_unlikely (tpi_supported == 0)) - { - int lock = 0; - INTERNAL_SYSCALL_DECL (err); - int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI, - 0, 0); - assert (INTERNAL_SYSCALL_ERROR_P (ret, err)); - tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1; - } - if (__glibc_unlikely (tpi_supported < 0)) + if (__glibc_unlikely (prio_inherit_missing ())) return ENOTSUP; -#endif break; default: --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -276,6 +276,10 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); break; + /* The PI support requires the Linux futex system call. If that's not + available, pthread_mutex_init should never have allowed the type to + be set. So it will get the default case for an invalid type. */ +#ifdef __NR_futex case PTHREAD_MUTEX_PI_RECURSIVE_NP: case PTHREAD_MUTEX_PI_ERRORCHECK_NP: case PTHREAD_MUTEX_PI_NORMAL_NP: @@ -321,9 +325,9 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) } int newval = id; -#ifdef NO_INCR +# ifdef NO_INCR newval |= FUTEX_WAITERS; -#endif +# endif oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, newval, 0); @@ -377,9 +381,9 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) incremented which is not correct because the old owner has to be discounted. If we are not supposed to increment __nusers we actually have to decrement it here. */ -#ifdef NO_INCR +# ifdef NO_INCR --mutex->__data.__nusers; -#endif +# endif return EOWNERDEAD; } @@ -409,6 +413,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) } } break; +#endif /* __NR_futex. */ case PTHREAD_MUTEX_PP_RECURSIVE_NP: case PTHREAD_MUTEX_PP_ERRORCHECK_NP: --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -230,6 +230,10 @@ pthread_mutex_timedlock (mutex, abstime) THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); break; + /* The PI support requires the Linux futex system call. If that's not + available, pthread_mutex_init should never have allowed the type to + be set. So it will get the default case for an invalid type. */ +#ifdef __NR_futex case PTHREAD_MUTEX_PI_RECURSIVE_NP: case PTHREAD_MUTEX_PI_ERRORCHECK_NP: case PTHREAD_MUTEX_PI_NORMAL_NP: @@ -382,6 +386,7 @@ pthread_mutex_timedlock (mutex, abstime) } } break; +#endif /* __NR_futex. */ case PTHREAD_MUTEX_PP_RECURSIVE_NP: case PTHREAD_MUTEX_PP_ERRORCHECK_NP: --- a/nptl/pthread_mutex_trylock.c +++ b/nptl/pthread_mutex_trylock.c @@ -191,6 +191,10 @@ __pthread_mutex_trylock (mutex) return 0; + /* The PI support requires the Linux futex system call. If that's not + available, pthread_mutex_init should never have allowed the type to + be set. So it will get the default case for an invalid type. */ +#ifdef __NR_futex case PTHREAD_MUTEX_PI_RECURSIVE_NP: case PTHREAD_MUTEX_PI_ERRORCHECK_NP: case PTHREAD_MUTEX_PI_NORMAL_NP: @@ -319,6 +323,7 @@ __pthread_mutex_trylock (mutex) return 0; } +#endif /* __NR_futex. */ case PTHREAD_MUTEX_PP_RECURSIVE_NP: case PTHREAD_MUTEX_PP_ERRORCHECK_NP: --- a/nptl/pthread_mutex_unlock.c +++ b/nptl/pthread_mutex_unlock.c @@ -158,6 +158,10 @@ __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr) THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); break; + /* The PI support requires the Linux futex system call. If that's not + available, pthread_mutex_init should never have allowed the type to + be set. So it will get the default case for an invalid type. */ +#ifdef __NR_futex case PTHREAD_MUTEX_PI_RECURSIVE_NP: /* Recursive mutex. */ if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) @@ -245,6 +249,7 @@ __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr) THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); break; +#endif /* __NR_futex. */ case PTHREAD_MUTEX_PP_RECURSIVE_NP: /* Recursive mutex. */