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Merge "Preserve historical pthread_create scheduler behavior better."

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Elliott Hughes 2017-10-28 17:19:06 +00:00 committed by Gerrit Code Review
commit e379a20250
3 changed files with 19 additions and 4 deletions
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12
libc/bionic/pthread_attr.cpp
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@ -61,8 +61,10 @@ __BIONIC_WEAK_FOR_NATIVE_BRIDGE
int pthread_attr_setinheritsched(pthread_attr_t* attr, int flag) {
if (flag == PTHREAD_EXPLICIT_SCHED) {
attr->flags &= ~PTHREAD_ATTR_FLAG_INHERIT;
attr->flags |= PTHREAD_ATTR_FLAG_EXPLICIT;
} else if (flag == PTHREAD_INHERIT_SCHED) {
attr->flags |= PTHREAD_ATTR_FLAG_INHERIT;
attr->flags &= ~PTHREAD_ATTR_FLAG_EXPLICIT;
} else {
return EINVAL;
}
@ -71,8 +73,14 @@ int pthread_attr_setinheritsched(pthread_attr_t* attr, int flag) {
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
int pthread_attr_getinheritsched(const pthread_attr_t* attr, int* flag) {
*flag = (attr->flags & PTHREAD_ATTR_FLAG_INHERIT) ? PTHREAD_INHERIT_SCHED
: PTHREAD_EXPLICIT_SCHED;
if ((attr->flags & PTHREAD_ATTR_FLAG_INHERIT) != 0) {
*flag = PTHREAD_INHERIT_SCHED;
} else if ((attr->flags & PTHREAD_ATTR_FLAG_EXPLICIT) != 0) {
*flag = PTHREAD_EXPLICIT_SCHED;
} else {
// Historical behavior before P, when pthread_attr_setinheritsched was added.
*flag = (attr->sched_policy != SCHED_NORMAL) ? PTHREAD_EXPLICIT_SCHED : PTHREAD_INHERIT_SCHED;
}
return 0;
}

7
libc/bionic/pthread_create.cpp
View file

@ -122,7 +122,7 @@ int __init_thread(pthread_internal_t* thread) {
bool need_set = true;
int policy;
sched_param param;
if (thread->attr.flags & PTHREAD_ATTR_FLAG_INHERIT) {
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_INHERIT) != 0) {
// Unless the parent has SCHED_RESET_ON_FORK set, we've already inherited from the parent.
policy = sched_getscheduler(0);
need_set = ((policy & SCHED_RESET_ON_FORK) != 0);
@ -142,6 +142,11 @@ int __init_thread(pthread_internal_t* thread) {
policy = thread->attr.sched_policy;
param.sched_priority = thread->attr.sched_priority;
}
// Backwards compatibility: before P, Android didn't have pthread_attr_setinheritsched,
// and our behavior was neither of the POSIX behaviors.
if ((thread->attr.flags & (PTHREAD_ATTR_FLAG_INHERIT|PTHREAD_ATTR_FLAG_EXPLICIT)) == 0) {
need_set = (thread->attr.sched_policy != SCHED_NORMAL);
}
if (need_set) {
if (sched_setscheduler(thread->tid, policy, &param) == -1) {
async_safe_format_log(ANDROID_LOG_WARN, "libc",

4
libc/bionic/pthread_internal.h
View file

@ -40,8 +40,10 @@
// Has the thread been joined by another thread?
#define PTHREAD_ATTR_FLAG_JOINED 0x00000002
// Should we inherit scheduling attributes from the parent on pthread_create?
// Used for pthread_attr_setinheritsched. We need two flags for this apparent
// boolean because our historical behavior matches neither of the POSIX choices.
#define PTHREAD_ATTR_FLAG_INHERIT 0x00000004
#define PTHREAD_ATTR_FLAG_EXPLICIT 0x00000008
class pthread_key_data_t {
public: