mirrors/musl
1
0
Fork 0
mirror of https://git.musl-libc.org/git/musl synced 2025-01-10 16:42:59 +03:00
Code Issues Packages Projects Releases Wiki Activity

optimize out setting up robust list with kernel when not needed

Browse Source 
as a result of commit 12e1e32468, 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.
This commit is contained in:
Rich Felker 2015-04-10 00:54:48 -04:00
parent 12e1e32468
commit 4e98cce1c5
4 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/env/__init_tls.c vendored
View File

@ -18,6 +18,7 @@ int __init_tp(void *p)
libc.has_thread_pointer = 1;
td->tid = __syscall(SYS_set_tid_address, &td->tid);
td->locale = &libc.global_locale;
td->robust_list.head = &td->robust_list.head;
return 0;
}

3
src/process/fork.c
View File

@ -25,7 +25,8 @@ pid_t fork(void)
if (libc.has_thread_pointer && !ret) {
pthread_t self = __pthread_self();
self->tid = __syscall(SYS_gettid);
memset(&self->robust_list, 0, sizeof self->robust_list);
self->robust_list.off = 0;
self->robust_list.pending = 0;
libc.threads_minus_1 = 0;
}
__restore_sigs(&set);

1
src/thread/pthread_create.c
View File

@ -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;

10
src/thread/pthread_mutex_trylock.c
View File

@ -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;
}