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author | Rich Felker <dalias@aerifal.cx> | 2015-04-10 00:54:48 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2015-04-10 00:54:48 -0400 |
commit | 4e98cce1c529a304d7b55b5455078b9532f93e9b (patch) | |
tree | a824ce64116146e20de6264fe4e91405fd1a2124 /src/thread | |
parent | 12e1e324683a1d381b7f15dd36c99b37dd44d940 (diff) | |
download | musl-4e98cce1c529a304d7b55b5455078b9532f93e9b.tar.gz musl-4e98cce1c529a304d7b55b5455078b9532f93e9b.tar.bz2 musl-4e98cce1c529a304d7b55b5455078b9532f93e9b.tar.xz musl-4e98cce1c529a304d7b55b5455078b9532f93e9b.zip |
optimize out setting up robust list with kernel when not needed
as a result of commit 12e1e324683a1d381b7f15dd36c99b37dd44d940, kernel
processing of the robust list is only needed for process-shared
mutexes. previously the first attempt to lock any owner-tracked mutex
resulted in robust list initialization and a set_robust_list syscall.
this is no longer necessary, and since the kernel's record of the
robust list must now be cleared at thread exit time for detached
threads, optimizing it out is more worthwhile than before too.
Diffstat (limited to 'src/thread')
-rw-r--r-- | src/thread/pthread_create.c | 1 | ||||
-rw-r--r-- | src/thread/pthread_mutex_trylock.c | 10 |
2 files changed, 5 insertions, 6 deletions
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c index 893773fa..8b0135bc 100644 --- a/src/thread/pthread_create.c +++ b/src/thread/pthread_create.c @@ -268,6 +268,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att do_sched = new->startlock[0] = 1; __block_app_sigs(new->sigmask); } + new->robust_list.head = &new->robust_list.head; new->unblock_cancel = self->cancel; new->canary = self->canary; diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c index cb935651..0df3ce29 100644 --- a/src/thread/pthread_mutex_trylock.c +++ b/src/thread/pthread_mutex_trylock.c @@ -7,12 +7,6 @@ int __pthread_mutex_trylock_owner(pthread_mutex_t *m) pthread_t self = __pthread_self(); int tid = self->tid; - if (!self->robust_list.off) { - __syscall(SYS_set_robust_list, &self->robust_list, 3*sizeof(long)); - self->robust_list.head = &self->robust_list.head; - self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next; - } - old = m->_m_lock; own = old & 0x7fffffff; if (own == tid && (type&3) == PTHREAD_MUTEX_RECURSIVE) { @@ -23,6 +17,10 @@ int __pthread_mutex_trylock_owner(pthread_mutex_t *m) if (own == 0x40000000) return ENOTRECOVERABLE; if (m->_m_type & 128) { + if (!self->robust_list.off) { + self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next; + __syscall(SYS_set_robust_list, &self->robust_list, 3*sizeof(long)); + } if (m->_m_waiters) tid |= 0x80000000; self->robust_list.pending = &m->_m_next; } |