From 8f861542dd0603bef99e126e509ece89514c1eeb Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Mon, 5 Nov 2012 21:12:10 +0530 Subject: [S390,PPC] Implement FUTEX_WAIT_BITSET for timedwait functions Since the FUTEX_WAIT operation takes a relative timeout, the pthread_cond_timedwait and other timed function implementations have to get a relative timeout from the absolute timeout parameter it gets before it makes the futex syscall. This value is then converted back into an absolute timeout within the kernel. This is a waste and has hence been improved upon by a FUTEX_WAIT_BITSET operation (OR'd with FUTEX_CLOCK_REALTIME to make the kernel use the realtime clock instead of the default monotonic clock). This was implemented only in the x86 and sh assembly code and not in the C code. This patch implements support for FUTEX_WAIT_BITSET whenever available (since linux-2.6.29) for s390 and powerpc. --- nptl/pthread_rwlock_timedrdlock.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'nptl/pthread_rwlock_timedrdlock.c') diff --git a/nptl/pthread_rwlock_timedrdlock.c b/nptl/pthread_rwlock_timedrdlock.c index be8216d579..b7622abfa2 100644 --- a/nptl/pthread_rwlock_timedrdlock.c +++ b/nptl/pthread_rwlock_timedrdlock.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2003,2004,2007,2011 Free Software Foundation, Inc. +/* Copyright (C) 2003-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Martin Schwidefsky , 2003. @@ -76,6 +76,16 @@ pthread_rwlock_timedrdlock (rwlock, abstime) break; } + /* Work around the fact that the kernel rejects negative timeout values + despite them being valid. */ + if (__builtin_expect (abstime->tv_sec < 0, 0)) + { + result = ETIMEDOUT; + break; + } + +#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ + || !defined lll_futex_timed_wait_bitset) /* Get the current time. So far we support only one clock. */ struct timeval tv; (void) gettimeofday (&tv, NULL); @@ -96,6 +106,7 @@ pthread_rwlock_timedrdlock (rwlock, abstime) result = ETIMEDOUT; break; } +#endif /* Remember that we are a reader. */ if (++rwlock->__data.__nr_readers_queued == 0) @@ -112,8 +123,16 @@ pthread_rwlock_timedrdlock (rwlock, abstime) lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared); /* Wait for the writer to finish. */ +#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ + || !defined lll_futex_timed_wait_bitset) err = lll_futex_timed_wait (&rwlock->__data.__readers_wakeup, waitval, &rt, rwlock->__data.__shared); +#else + err = lll_futex_timed_wait_bitset (&rwlock->__data.__readers_wakeup, + waitval, abstime, + FUTEX_CLOCK_REALTIME, + rwlock->__data.__shared); +#endif /* Get the lock. */ lll_lock (rwlock->__data.__lock, rwlock->__data.__shared); -- cgit v1.2.3