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-rw-r--r--libc/bionic/pthread.c655
1 files changed, 405 insertions, 250 deletions
diff --git a/libc/bionic/pthread.c b/libc/bionic/pthread.c
index 7d4056d..6a2329f 100644
--- a/libc/bionic/pthread.c
+++ b/libc/bionic/pthread.c
@@ -43,12 +43,16 @@
#include <memory.h>
#include <assert.h>
#include <malloc.h>
+#include <linux/futex.h>
extern int __pthread_clone(int (*fn)(void*), void *child_stack, int flags, void *arg);
extern void _exit_with_stack_teardown(void * stackBase, int stackSize, int retCode);
extern void _exit_thread(int retCode);
extern int __set_errno(int);
+#define __likely(cond) __builtin_expect(!!(cond), 1)
+#define __unlikely(cond) __builtin_expect(!!(cond), 0)
+
void _thread_created_hook(pid_t thread_id) __attribute__((noinline));
#define PTHREAD_ATTR_FLAG_DETACHED 0x00000001
@@ -711,6 +715,21 @@ int pthread_setschedparam(pthread_t thid, int policy,
int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
int __futex_wake(volatile void *ftx, int count);
+int __futex_syscall3(volatile void *ftx, int op, int val);
+int __futex_syscall4(volatile void *ftx, int op, int val, const struct timespec *timeout);
+
+#ifndef FUTEX_PRIVATE_FLAG
+#define FUTEX_PRIVATE_FLAG 128
+#endif
+
+#ifndef FUTEX_WAIT_PRIVATE
+#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT|FUTEX_PRIVATE_FLAG)
+#endif
+
+#ifndef FUTEX_WAKE_PRIVATE
+#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE|FUTEX_PRIVATE_FLAG)
+#endif
+
// mutex lock states
//
// 0: unlocked
@@ -722,7 +741,8 @@ int __futex_wake(volatile void *ftx, int count);
* bits: name description
* 31-16 tid owner thread's kernel id (recursive and errorcheck only)
* 15-14 type mutex type
- * 13-2 counter counter of recursive mutexes
+ * 13 shared process-shared flag
+ * 12-2 counter counter of recursive mutexes
* 1-0 state lock state (0, 1 or 2)
*/
@@ -736,9 +756,17 @@ int __futex_wake(volatile void *ftx, int count);
#define MUTEX_TYPE_ERRORCHECK 0x8000
#define MUTEX_COUNTER_SHIFT 2
-#define MUTEX_COUNTER_MASK 0x3ffc
-
+#define MUTEX_COUNTER_MASK 0x1ffc
+#define MUTEX_SHARED_MASK 0x2000
+/* a mutex attribute holds the following fields
+ *
+ * bits: name description
+ * 0-3 type type of mutex
+ * 4 shared process-shared flag
+ */
+#define MUTEXATTR_TYPE_MASK 0x000f
+#define MUTEXATTR_SHARED_MASK 0x0010
int pthread_mutexattr_init(pthread_mutexattr_t *attr)
@@ -763,10 +791,14 @@ int pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
int pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *type)
{
- if (attr && *attr >= PTHREAD_MUTEX_NORMAL &&
- *attr <= PTHREAD_MUTEX_ERRORCHECK ) {
- *type = *attr;
- return 0;
+ if (attr) {
+ int atype = (*attr & MUTEXATTR_TYPE_MASK);
+
+ if (atype >= PTHREAD_MUTEX_NORMAL &&
+ atype <= PTHREAD_MUTEX_ERRORCHECK) {
+ *type = atype;
+ return 0;
+ }
}
return EINVAL;
}
@@ -775,7 +807,7 @@ int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type)
{
if (attr && type >= PTHREAD_MUTEX_NORMAL &&
type <= PTHREAD_MUTEX_ERRORCHECK ) {
- *attr = type;
+ *attr = (*attr & ~MUTEXATTR_TYPE_MASK) | type;
return 0;
}
return EINVAL;
@@ -790,54 +822,70 @@ int pthread_mutexattr_setpshared(pthread_mutexattr_t *attr, int pshared)
switch (pshared) {
case PTHREAD_PROCESS_PRIVATE:
+ *attr &= ~MUTEXATTR_SHARED_MASK;
+ return 0;
+
case PTHREAD_PROCESS_SHARED:
/* our current implementation of pthread actually supports shared
* mutexes but won't cleanup if a process dies with the mutex held.
* Nevertheless, it's better than nothing. Shared mutexes are used
* by surfaceflinger and audioflinger.
*/
+ *attr |= MUTEXATTR_SHARED_MASK;
return 0;
}
-
- return ENOTSUP;
+ return EINVAL;
}
int pthread_mutexattr_getpshared(pthread_mutexattr_t *attr, int *pshared)
{
- if (!attr)
+ if (!attr || !pshared)
return EINVAL;
- *pshared = PTHREAD_PROCESS_PRIVATE;
+ *pshared = (*attr & MUTEXATTR_SHARED_MASK) ? PTHREAD_PROCESS_SHARED
+ : PTHREAD_PROCESS_PRIVATE;
return 0;
}
int pthread_mutex_init(pthread_mutex_t *mutex,
const pthread_mutexattr_t *attr)
{
- if ( mutex ) {
- if (attr == NULL) {
- mutex->value = MUTEX_TYPE_NORMAL;
- return 0;
- }
- switch ( *attr ) {
- case PTHREAD_MUTEX_NORMAL:
- mutex->value = MUTEX_TYPE_NORMAL;
- return 0;
+ int value = 0;
- case PTHREAD_MUTEX_RECURSIVE:
- mutex->value = MUTEX_TYPE_RECURSIVE;
- return 0;
+ if (mutex == NULL)
+ return EINVAL;
- case PTHREAD_MUTEX_ERRORCHECK:
- mutex->value = MUTEX_TYPE_ERRORCHECK;
- return 0;
- }
+ if (__likely(attr == NULL)) {
+ mutex->value = MUTEX_TYPE_NORMAL;
+ return 0;
}
- return EINVAL;
+
+ if ((*attr & MUTEXATTR_SHARED_MASK) != 0)
+ value |= MUTEX_SHARED_MASK;
+
+ switch (*attr & MUTEXATTR_TYPE_MASK) {
+ case PTHREAD_MUTEX_NORMAL:
+ value |= MUTEX_TYPE_NORMAL;
+ break;
+ case PTHREAD_MUTEX_RECURSIVE:
+ value |= MUTEX_TYPE_RECURSIVE;
+ break;
+ case PTHREAD_MUTEX_ERRORCHECK:
+ value |= MUTEX_TYPE_ERRORCHECK;
+ break;
+ default:
+ return EINVAL;
+ }
+
+ mutex->value = value;
+ return 0;
}
int pthread_mutex_destroy(pthread_mutex_t *mutex)
{
+ if (__unlikely(mutex == NULL))
+ return EINVAL;
+
mutex->value = 0xdead10cc;
return 0;
}
@@ -858,13 +906,15 @@ int pthread_mutex_destroy(pthread_mutex_t *mutex)
static __inline__ void
_normal_lock(pthread_mutex_t* mutex)
{
+ /* We need to preserve the shared flag during operations */
+ int shared = mutex->value & MUTEX_SHARED_MASK;
/*
* The common case is an unlocked mutex, so we begin by trying to
* change the lock's state from 0 to 1. __atomic_cmpxchg() returns 0
* if it made the swap successfully. If the result is nonzero, this
* lock is already held by another thread.
*/
- if (__atomic_cmpxchg(0, 1, &mutex->value ) != 0) {
+ if (__atomic_cmpxchg(shared|0, shared|1, &mutex->value ) != 0) {
/*
* We want to go to sleep until the mutex is available, which
* requires promoting it to state 2. We need to swap in the new
@@ -881,8 +931,10 @@ _normal_lock(pthread_mutex_t* mutex)
* that the mutex is in state 2 when we go to sleep on it, which
* guarantees a wake-up call.
*/
- while (__atomic_swap(2, &mutex->value ) != 0)
- __futex_wait(&mutex->value, 2, 0);
+ int wait_op = shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE;
+
+ while (__atomic_swap(shared|2, &mutex->value ) != (shared|0))
+ __futex_syscall4(&mutex->value, wait_op, shared|2, 0);
}
}
@@ -893,12 +945,16 @@ _normal_lock(pthread_mutex_t* mutex)
static __inline__ void
_normal_unlock(pthread_mutex_t* mutex)
{
+ /* We need to preserve the shared flag during operations */
+ int shared = mutex->value & MUTEX_SHARED_MASK;
+
/*
- * The mutex value will be 1 or (rarely) 2. We use an atomic decrement
+ * The mutex state will be 1 or (rarely) 2. We use an atomic decrement
* to release the lock. __atomic_dec() returns the previous value;
* if it wasn't 1 we have to do some additional work.
*/
- if (__atomic_dec(&mutex->value) != 1) {
+ if (__atomic_dec(&mutex->value) != (shared|1)) {
+ int wake_op = shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE;
/*
* Start by releasing the lock. The decrement changed it from
* "contended lock" to "uncontended lock", which means we still
@@ -913,7 +969,7 @@ _normal_unlock(pthread_mutex_t* mutex)
* _normal_lock(), because the __futex_wait() call there will
* return immediately if the mutex value isn't 2.
*/
- mutex->value = 0;
+ mutex->value = shared;
/*
* Wake up one waiting thread. We don't know which thread will be
@@ -936,7 +992,7 @@ _normal_unlock(pthread_mutex_t* mutex)
* Either way we have correct behavior and nobody is orphaned on
* the wait queue.
*/
- __futex_wake(&mutex->value, 1);
+ __futex_syscall3(&mutex->value, wake_op, 1);
}
}
@@ -945,182 +1001,188 @@ static pthread_mutex_t __recursive_lock = PTHREAD_MUTEX_INITIALIZER;
static void
_recursive_lock(void)
{
- _normal_lock( &__recursive_lock);
+ _normal_lock(&__recursive_lock);
}
static void
_recursive_unlock(void)
{
- _normal_unlock( &__recursive_lock );
+ _normal_unlock(&__recursive_lock );
}
-#define __likely(cond) __builtin_expect(!!(cond), 1)
-#define __unlikely(cond) __builtin_expect(!!(cond), 0)
-
int pthread_mutex_lock(pthread_mutex_t *mutex)
{
- if (__likely(mutex != NULL))
- {
- int mtype = (mutex->value & MUTEX_TYPE_MASK);
+ int mtype, tid, new_lock_type, shared, wait_op;
- if ( __likely(mtype == MUTEX_TYPE_NORMAL) ) {
- _normal_lock(mutex);
- }
- else
- {
- int tid = __get_thread()->kernel_id;
+ if (__unlikely(mutex == NULL))
+ return EINVAL;
- if ( tid == MUTEX_OWNER(mutex) )
- {
- int oldv, counter;
+ mtype = (mutex->value & MUTEX_TYPE_MASK);
+ shared = (mutex->value & MUTEX_SHARED_MASK);
- if (mtype == MUTEX_TYPE_ERRORCHECK) {
- /* trying to re-lock a mutex we already acquired */
- return EDEADLK;
- }
- /*
- * We own the mutex, but other threads are able to change
- * the contents (e.g. promoting it to "contended"), so we
- * need to hold the global lock.
- */
- _recursive_lock();
- oldv = mutex->value;
- counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
- mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
- _recursive_unlock();
- }
- else
- {
- /*
- * If the new lock is available immediately, we grab it in
- * the "uncontended" state.
- */
- int new_lock_type = 1;
-
- for (;;) {
- int oldv;
-
- _recursive_lock();
- oldv = mutex->value;
- if (oldv == mtype) { /* uncontended released lock => 1 or 2 */
- mutex->value = ((tid << 16) | mtype | new_lock_type);
- } else if ((oldv & 3) == 1) { /* locked state 1 => state 2 */
- oldv ^= 3;
- mutex->value = oldv;
- }
- _recursive_unlock();
-
- if (oldv == mtype)
- break;
-
- /*
- * The lock was held, possibly contended by others. From
- * now on, if we manage to acquire the lock, we have to
- * assume that others are still contending for it so that
- * we'll wake them when we unlock it.
- */
- new_lock_type = 2;
-
- __futex_wait( &mutex->value, oldv, 0 );
- }
- }
+ /* Handle normal case first */
+ if ( __likely(mtype == MUTEX_TYPE_NORMAL) ) {
+ _normal_lock(mutex);
+ return 0;
+ }
+
+ /* Do we already own this recursive or error-check mutex ? */
+ tid = __get_thread()->kernel_id;
+ if ( tid == MUTEX_OWNER(mutex) )
+ {
+ int oldv, counter;
+
+ if (mtype == MUTEX_TYPE_ERRORCHECK) {
+ /* trying to re-lock a mutex we already acquired */
+ return EDEADLK;
}
+ /*
+ * We own the mutex, but other threads are able to change
+ * the contents (e.g. promoting it to "contended"), so we
+ * need to hold the global lock.
+ */
+ _recursive_lock();
+ oldv = mutex->value;
+ counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
+ mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
+ _recursive_unlock();
return 0;
}
- return EINVAL;
+
+ /* We don't own the mutex, so try to get it.
+ *
+ * First, we try to change its state from 0 to 1, if this
+ * doesn't work, try to change it to state 2.
+ */
+ new_lock_type = 1;
+
+ /* compute futex wait opcode and restore shared flag in mtype */
+ wait_op = shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE;
+ mtype |= shared;
+
+ for (;;) {
+ int oldv;
+
+ _recursive_lock();
+ oldv = mutex->value;
+ if (oldv == mtype) { /* uncontended released lock => 1 or 2 */
+ mutex->value = ((tid << 16) | mtype | new_lock_type);
+ } else if ((oldv & 3) == 1) { /* locked state 1 => state 2 */
+ oldv ^= 3;
+ mutex->value = oldv;
+ }
+ _recursive_unlock();
+
+ if (oldv == mtype)
+ break;
+
+ /*
+ * The lock was held, possibly contended by others. From
+ * now on, if we manage to acquire the lock, we have to
+ * assume that others are still contending for it so that
+ * we'll wake them when we unlock it.
+ */
+ new_lock_type = 2;
+
+ __futex_syscall4(&mutex->value, wait_op, oldv, NULL);
+ }
+ return 0;
}
int pthread_mutex_unlock(pthread_mutex_t *mutex)
{
- if (__likely(mutex != NULL))
- {
- int mtype = (mutex->value & MUTEX_TYPE_MASK);
+ int mtype, tid, oldv, shared;
- if (__likely(mtype == MUTEX_TYPE_NORMAL)) {
- _normal_unlock(mutex);
- }
- else
- {
- int tid = __get_thread()->kernel_id;
+ if (__unlikely(mutex == NULL))
+ return EINVAL;
- if ( tid == MUTEX_OWNER(mutex) )
- {
- int oldv;
-
- _recursive_lock();
- oldv = mutex->value;
- if (oldv & MUTEX_COUNTER_MASK) {
- mutex->value = oldv - (1 << MUTEX_COUNTER_SHIFT);
- oldv = 0;
- } else {
- mutex->value = mtype;
- }
- _recursive_unlock();
+ mtype = (mutex->value & MUTEX_TYPE_MASK);
+ shared = (mutex->value & MUTEX_SHARED_MASK);
- if ((oldv & 3) == 2)
- __futex_wake( &mutex->value, 1 );
- }
- else {
- /* trying to unlock a lock we do not own */
- return EPERM;
- }
- }
+ /* Handle common case first */
+ if (__likely(mtype == MUTEX_TYPE_NORMAL)) {
+ _normal_unlock(mutex);
return 0;
}
- return EINVAL;
+
+ /* Do we already own this recursive or error-check mutex ? */
+ tid = __get_thread()->kernel_id;
+ if ( tid != MUTEX_OWNER(mutex) )
+ return EPERM;
+
+ /* We do, decrement counter or release the mutex if it is 0 */
+ _recursive_lock();
+ oldv = mutex->value;
+ if (oldv & MUTEX_COUNTER_MASK) {
+ mutex->value = oldv - (1 << MUTEX_COUNTER_SHIFT);
+ oldv = 0;
+ } else {
+ mutex->value = shared | mtype;
+ }
+ _recursive_unlock();
+
+ /* Wake one waiting thread, if any */
+ if ((oldv & 3) == 2) {
+ int wake_op = shared ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT;
+ __futex_syscall3(&mutex->value, wake_op, 1);
+ }
+ return 0;
}
int pthread_mutex_trylock(pthread_mutex_t *mutex)
{
- if (__likely(mutex != NULL))
+ int mtype, tid, oldv, shared;
+
+ if (__unlikely(mutex == NULL))
+ return EINVAL;
+
+ mtype = (mutex->value & MUTEX_TYPE_MASK);
+ shared = (mutex->value & MUTEX_SHARED_MASK);
+
+ /* Handle common case first */
+ if ( __likely(mtype == MUTEX_TYPE_NORMAL) )
{
- int mtype = (mutex->value & MUTEX_TYPE_MASK);
+ if (__atomic_cmpxchg(shared|0, shared|1, &mutex->value) == 0)
+ return 0;
- if ( __likely(mtype == MUTEX_TYPE_NORMAL) )
- {
- if (__atomic_cmpxchg(0, 1, &mutex->value) == 0)
- return 0;
+ return EBUSY;
+ }
- return EBUSY;
- }
- else
- {
- int tid = __get_thread()->kernel_id;
- int oldv;
+ /* Do we already own this recursive or error-check mutex ? */
+ tid = __get_thread()->kernel_id;
+ if ( tid == MUTEX_OWNER(mutex) )
+ {
+ int counter;
- if ( tid == MUTEX_OWNER(mutex) )
- {
- int oldv, counter;
+ if (mtype == MUTEX_TYPE_ERRORCHECK) {
+ /* already locked by ourselves */
+ return EDEADLK;
+ }
- if (mtype == MUTEX_TYPE_ERRORCHECK) {
- /* already locked by ourselves */
- return EDEADLK;
- }
+ _recursive_lock();
+ oldv = mutex->value;
+ counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
+ mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
+ _recursive_unlock();
+ return 0;
+ }
- _recursive_lock();
- oldv = mutex->value;
- counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
- mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
- _recursive_unlock();
- return 0;
- }
+ /* Restore sharing bit in mtype */
+ mtype |= shared;
- /* try to lock it */
- _recursive_lock();
- oldv = mutex->value;
- if (oldv == mtype) /* uncontended released lock => state 1 */
- mutex->value = ((tid << 16) | mtype | 1);
- _recursive_unlock();
+ /* Try to lock it, just once. */
+ _recursive_lock();
+ oldv = mutex->value;
+ if (oldv == mtype) /* uncontended released lock => state 1 */
+ mutex->value = ((tid << 16) | mtype | 1);
+ _recursive_unlock();
- if (oldv != mtype)
- return EBUSY;
+ if (oldv != mtype)
+ return EBUSY;
- return 0;
- }
- }
- return EINVAL;
+ return 0;
}
@@ -1163,100 +1225,150 @@ int pthread_mutex_lock_timeout_np(pthread_mutex_t *mutex, unsigned msecs)
clockid_t clock = CLOCK_MONOTONIC;
struct timespec abstime;
struct timespec ts;
+ int mtype, tid, oldv, new_lock_type, shared, wait_op;
/* compute absolute expiration time */
__timespec_to_relative_msec(&abstime, msecs, clock);
- if (__likely(mutex != NULL))
- {
- int mtype = (mutex->value & MUTEX_TYPE_MASK);
+ if (__unlikely(mutex == NULL))
+ return EINVAL;
- if ( __likely(mtype == MUTEX_TYPE_NORMAL) )
- {
- /* fast path for unconteded lock */
- if (__atomic_cmpxchg(0, 1, &mutex->value) == 0)
- return 0;
+ mtype = (mutex->value & MUTEX_TYPE_MASK);
+ shared = (mutex->value & MUTEX_SHARED_MASK);
- /* loop while needed */
- while (__atomic_swap(2, &mutex->value) != 0) {
- if (__timespec_to_absolute(&ts, &abstime, clock) < 0)
- return EBUSY;
+ /* Handle common case first */
+ if ( __likely(mtype == MUTEX_TYPE_NORMAL) )
+ {
+ int wait_op = shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE;
- __futex_wait(&mutex->value, 2, &ts);
- }
+ /* fast path for unconteded lock */
+ if (__atomic_cmpxchg(shared|0, shared|1, &mutex->value) == 0)
return 0;
+
+ /* loop while needed */
+ while (__atomic_swap(shared|2, &mutex->value) != (shared|0)) {
+ if (__timespec_to_absolute(&ts, &abstime, clock) < 0)
+ return EBUSY;
+
+ __futex_syscall4(&mutex->value, wait_op, shared|2, &ts);
}
- else
- {
- int tid = __get_thread()->kernel_id;
- int oldv;
+ return 0;
+ }
- if ( tid == MUTEX_OWNER(mutex) )
- {
- int oldv, counter;
+ /* Do we already own this recursive or error-check mutex ? */
+ tid = __get_thread()->kernel_id;
+ if ( tid == MUTEX_OWNER(mutex) )
+ {
+ int oldv, counter;
- if (mtype == MUTEX_TYPE_ERRORCHECK) {
- /* already locked by ourselves */
- return EDEADLK;
- }
+ if (mtype == MUTEX_TYPE_ERRORCHECK) {
+ /* already locked by ourselves */
+ return EDEADLK;
+ }
- _recursive_lock();
- oldv = mutex->value;
- counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
- mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
- _recursive_unlock();
- return 0;
- }
- else
- {
- /*
- * If the new lock is available immediately, we grab it in
- * the "uncontended" state.
- */
- int new_lock_type = 1;
-
- for (;;) {
- int oldv;
- struct timespec ts;
-
- _recursive_lock();
- oldv = mutex->value;
- if (oldv == mtype) { /* uncontended released lock => 1 or 2 */
- mutex->value = ((tid << 16) | mtype | new_lock_type);
- } else if ((oldv & 3) == 1) { /* locked state 1 => state 2 */
- oldv ^= 3;
- mutex->value = oldv;
- }
- _recursive_unlock();
-
- if (oldv == mtype)
- break;
-
- /*
- * The lock was held, possibly contended by others. From
- * now on, if we manage to acquire the lock, we have to
- * assume that others are still contending for it so that
- * we'll wake them when we unlock it.
- */
- new_lock_type = 2;
-
- if (__timespec_to_absolute(&ts, &abstime, clock) < 0)
- return EBUSY;
-
- __futex_wait( &mutex->value, oldv, &ts );
- }
- return 0;
- }
+ _recursive_lock();
+ oldv = mutex->value;
+ counter = (oldv + (1 << MUTEX_COUNTER_SHIFT)) & MUTEX_COUNTER_MASK;
+ mutex->value = (oldv & ~MUTEX_COUNTER_MASK) | counter;
+ _recursive_unlock();
+ return 0;
+ }
+
+ /* We don't own the mutex, so try to get it.
+ *
+ * First, we try to change its state from 0 to 1, if this
+ * doesn't work, try to change it to state 2.
+ */
+ new_lock_type = 1;
+
+ /* Compute wait op and restore sharing bit in mtype */
+ wait_op = shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE;
+ mtype |= shared;
+
+ for (;;) {
+ int oldv;
+ struct timespec ts;
+
+ _recursive_lock();
+ oldv = mutex->value;
+ if (oldv == mtype) { /* uncontended released lock => 1 or 2 */
+ mutex->value = ((tid << 16) | mtype | new_lock_type);
+ } else if ((oldv & 3) == 1) { /* locked state 1 => state 2 */
+ oldv ^= 3;
+ mutex->value = oldv;
}
+ _recursive_unlock();
+
+ if (oldv == mtype)
+ break;
+
+ /*
+ * The lock was held, possibly contended by others. From
+ * now on, if we manage to acquire the lock, we have to
+ * assume that others are still contending for it so that
+ * we'll wake them when we unlock it.
+ */
+ new_lock_type = 2;
+
+ if (__timespec_to_absolute(&ts, &abstime, clock) < 0)
+ return EBUSY;
+
+ __futex_syscall4(&mutex->value, wait_op, oldv, &ts);
}
- return EINVAL;
+ return 0;
}
+int pthread_condattr_init(pthread_condattr_t *attr)
+{
+ if (attr == NULL)
+ return EINVAL;
+
+ *attr = PTHREAD_PROCESS_PRIVATE;
+ return 0;
+}
+
+int pthread_condattr_getpshared(pthread_condattr_t *attr, int *pshared)
+{
+ if (attr == NULL || pshared == NULL)
+ return EINVAL;
+
+ *pshared = *attr;
+ return 0;
+}
+
+int pthread_condattr_setpshared(pthread_condattr_t *attr, int pshared)
+{
+ if (attr == NULL)
+ return EINVAL;
+
+ if (pshared != PTHREAD_PROCESS_SHARED &&
+ pshared != PTHREAD_PROCESS_PRIVATE)
+ return EINVAL;
+
+ *attr = pshared;
+ return 0;
+}
+
+int pthread_condattr_destroy(pthread_condattr_t *attr)
+{
+ if (attr == NULL)
+ return EINVAL;
+
+ *attr = 0xdeada11d;
+ return 0;
+}
+
+/* We use one bit in condition variable values as the 'shared' flag
+ * The rest is a counter.
+ */
+#define COND_SHARING_MASK 0x0001
+#define COND_COUNTER_INCREMENT 0x0002
+#define COND_COUNTER_MASK (~COND_SHARING_MASK)
/* XXX *technically* there is a race condition that could allow
* XXX a signal to be missed. If thread A is preempted in _wait()
* XXX after unlocking the mutex and before waiting, and if other
- * XXX threads call signal or broadcast UINT_MAX times (exactly),
+ * XXX threads call signal or broadcast UINT_MAX/2 times (exactly),
* XXX before thread A is scheduled again and calls futex_wait(),
* XXX then the signal will be lost.
*/
@@ -1264,26 +1376,59 @@ int pthread_mutex_lock_timeout_np(pthread_mutex_t *mutex, unsigned msecs)
int pthread_cond_init(pthread_cond_t *cond,
const pthread_condattr_t *attr)
{
+ if (cond == NULL)
+ return EINVAL;
+
cond->value = 0;
+
+ if (attr != NULL && *attr == PTHREAD_PROCESS_SHARED)
+ cond->value |= COND_SHARING_MASK;
+
return 0;
}
int pthread_cond_destroy(pthread_cond_t *cond)
{
+ if (cond == NULL)
+ return EINVAL;
+
cond->value = 0xdeadc04d;
return 0;
}
+/* This function is used by pthread_cond_broadcast and
+ * pthread_cond_signal to atomically decrement the counter.
+ */
+static void
+__pthread_cond_pulse(pthread_cond_t *cond)
+{
+ long flags = (cond->value & ~COND_COUNTER_MASK);
+
+ for (;;) {
+ long oldval = cond->value;
+ long newval = ((oldval - COND_COUNTER_INCREMENT) & COND_COUNTER_MASK)
+ | flags;
+ if (__atomic_cmpxchg(oldval, newval, &cond->value) == 0)
+ break;
+ }
+}
+
int pthread_cond_broadcast(pthread_cond_t *cond)
{
- __atomic_dec(&cond->value);
+ if (__unlikely(cond == NULL))
+ return EINVAL;
+
+ __pthread_cond_pulse(cond);
__futex_wake(&cond->value, INT_MAX);
return 0;
}
int pthread_cond_signal(pthread_cond_t *cond)
{
- __atomic_dec(&cond->value);
+ if (__unlikely(cond == NULL))
+ return EINVAL;
+
+ __pthread_cond_pulse(cond);
__futex_wake(&cond->value, 1);
return 0;
}
@@ -1687,7 +1832,17 @@ extern int __rt_sigprocmask(int, const sigset_t *, sigset_t *, size_t);
int pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
{
- return __rt_sigprocmask(how, set, oset, _NSIG / 8);
+ /* pthread_sigmask must return the error code, but the syscall
+ * will set errno instead and return 0/-1
+ */
+ int ret, old_errno = errno;
+
+ ret = __rt_sigprocmask(how, set, oset, _NSIG / 8);
+ if (ret < 0)
+ ret = errno;
+
+ errno = old_errno;
+ return ret;
}
generated by cgit v1.1 at 2025-11-27 18:03:47 +0000