diff options
Diffstat (limited to 'nptl/sysdeps/unix/sysv/solaris2/kopensolaris-gnu/fastlock.c')
| -rw-r--r-- | nptl/sysdeps/unix/sysv/solaris2/kopensolaris-gnu/fastlock.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/nptl/sysdeps/unix/sysv/solaris2/kopensolaris-gnu/fastlock.c b/nptl/sysdeps/unix/sysv/solaris2/kopensolaris-gnu/fastlock.c new file mode 100644 index 0000000000..4612de0866 --- /dev/null +++ b/nptl/sysdeps/unix/sysv/solaris2/kopensolaris-gnu/fastlock.c @@ -0,0 +1,135 @@ +/* Copyright (C) 2008 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by David Bartley <dtbartle@csclub.uwaterloo.ca>, 2008. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <errno.h> +#include <pthreadP.h> +#include <synchP.h> +#include <sys/synch.h> +#include <stdbool.h> +#include <assert.h> + +int __mutex_lock_fast (mutex_t *mutex, bool try) +{ + if (mutex->mutex_lockword32 == LOCKWORD32_UNSET_NO_WAITERS) + { + /* The mutex is not held by anyone so try to grab it. */ + if (mutex->mutex_type & LOCK_SHARED) + { + uint64_t new_lockword64 = LOCKWORD64_SET_NO_WAITERS | + (THREAD_GETMEM (THREAD_SELF, pid) << MUTEX_OWNERPID_SHIFT); + uint64_t old_lockword64 = atomic_compare_and_exchange_val_acq ( + &mutex->mutex_lockword64, new_lockword64, + LOCKWORD64_UNSET_NO_WAITERS); + if (__builtin_expect (old_lockword64 == + LOCKWORD64_UNSET_NO_WAITERS, 1)) + { + mutex->mutex_owner = THREAD_GETMEM (THREAD_SELF, tid); + return 0; + } + } + else + { + uint32_t old_lockword32 = atomic_compare_and_exchange_val_acq ( + &mutex->mutex_lockword32, LOCKWORD32_SET_NO_WAITERS, + LOCKWORD32_UNSET_NO_WAITERS); + if (__builtin_expect (old_lockword32 == + LOCKWORD32_UNSET_NO_WAITERS, 1)) + { + mutex->mutex_owner = THREAD_GETMEM (THREAD_SELF, tid); + return 0; + } + } + } + else if ((mutex->mutex_type & LOCK_RECURSIVE) && MUTEX_IS_OWNER (mutex)) + { + /* Recursively held lock. */ + if (mutex->mutex_rcount == RECURSION_MAX) + return EAGAIN; + mutex->mutex_rcount++; + return 0; + } + else if ((mutex->mutex_type & LOCK_ERRORCHECK) && MUTEX_IS_OWNER (mutex)) + { + /* Error checking: lock already held. */ + return EDEADLK; + } + else if (try && mutex->mutex_lockbyte == LOCKBYTE_SET) + { + /* Tried to lock but lock was held. */ + return EBUSY; + } + + /* Need to use the slow code. */ + return -1; +} + + +int __mutex_unlock_fast (mutex_t *mutex) +{ + if ((mutex->mutex_type & LOCK_RECURSIVE) && MUTEX_IS_OWNER (mutex) && + mutex->mutex_rcount > 0) + { + /* Recursively held lock. */ + --mutex->mutex_rcount; + return 0; + } + else if ((mutex->mutex_type & LOCK_ERRORCHECK) && MUTEX_NOT_OWNER (mutex)) + { + /* error checking: lock not held by this thread */ + return EPERM; + } + else if (mutex->mutex_lockword32 == LOCKWORD32_SET_NO_WAITERS) + { + /* We need to clear the owner before we fully unlock. Otherwise + we have a race condition where we might clear the owner after + another thread sets the lock word. If we fail to unlock here + we don't need to reset the owner as we're just going to unlock + in the kernel (which doesn't check this field anyhow). */ + mutex->mutex_owner = 0; + + /* Nobody is waiting on the mutex so we can try to release it. */ + if (mutex->mutex_type & LOCK_SHARED) + { + uint64_t test_lockword64 = LOCKWORD64_SET_NO_WAITERS | + (mutex->mutex_ownerpid << MUTEX_OWNERPID_SHIFT); + (THREAD_GETMEM (THREAD_SELF, pid) << MUTEX_OWNERPID_SHIFT); + uint64_t old_lockword64 = atomic_compare_and_exchange_val_acq ( + &mutex->mutex_lockword64, LOCKWORD64_UNSET_NO_WAITERS, + test_lockword64); + if (__builtin_expect (old_lockword64 == test_lockword64, 1)) + { + return 0; + } + } + else + { + uint32_t old_lockword32 = atomic_compare_and_exchange_val_acq ( + &mutex->mutex_lockword32, LOCKWORD32_UNSET_NO_WAITERS, + LOCKWORD32_SET_NO_WAITERS); + if (__builtin_expect (old_lockword32 == + LOCKWORD32_SET_NO_WAITERS, 1)) + { + return 0; + } + } + } + + /* Need to use the slow code. */ + return -1; +} |