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/**
* @file futexmgr.C
* @brief Definition for kernel side futex management
*/
#include <assert.h>
#include <errno.h>
#include <kernel/task.H>
#include <kernel/cpumgr.H>
#include <kernel/scheduler.H>
#include <kernel/futexmgr.H>
#include <util/singleton.H>
//-----------------------------------------------------------------------------
uint64_t FutexManager::wait(task_t* i_task, uint64_t * i_addr, uint64_t i_val)
{
return Singleton<FutexManager>::instance()._wait(i_task, i_addr, i_val);
}
//-----------------------------------------------------------------------------
uint64_t FutexManager::wake(uint64_t * i_addr, uint64_t i_count)
{
return Singleton<FutexManager>::instance()._wake(i_addr, i_count);
}
//-----------------------------------------------------------------------------
uint64_t FutexManager::_wait(task_t* i_task, uint64_t * i_addr, uint64_t i_val)
{
uint64_t rc = 0;
iv_lock.lock();
if(unlikely(*i_addr != i_val))
{
// some other thread has modified the futex
// bail-out retry required.
iv_lock.unlock();
rc = EWOULDBLOCK;
}
else
{
_FutexWait_t * waiter = new _FutexWait_t();
waiter->key = i_addr;
waiter->task = i_task;
// Now add the futex/task it to the wait queue
iv_list.insert(waiter);
iv_lock.unlock();
CpuManager::getCurrentCPU()->scheduler->setNextRunnable();
}
return rc;
}
//-----------------------------------------------------------------------------
uint64_t FutexManager::_wake(uint64_t * i_addr, uint64_t i_count)
{
uint64_t started = 0;
// Remove task(s) from futex queue
// Put it/them on the run queue
iv_lock.lock();
while(started < i_count)
{
_FutexWait_t * waiter = iv_list.find(i_addr);
if(waiter == NULL)
{
break;
}
task_t * wait_task = waiter->task;
iv_list.erase(waiter);
// This means we had a waiter in the queue, but that waiter had
// a Null task assigned to it. This should NEVER happen
kassert(wait_task != NULL);
wait_task->cpu->scheduler->addTask(wait_task);
++started;
}
iv_lock.unlock();
return started;
}
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