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fix crash when wait_barrier_slow is called with a nil barrier #827

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fix crash when wait_barrier_slow is called with a nil barrier #827

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82 changes: 42 additions & 40 deletions src/base/base_threads.c
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Original file line number Diff line number Diff line change
Expand Up @@ -131,64 +131,66 @@ slow_barrier_wait(Barrier barrier)
{
ProfBeginFunction();
BarrierNode *n = (BarrierNode *)barrier.u64[0];
U64 threads_left_to_enter = ins_atomic_u64_dec_eval(&n->threads_left_to_enter);

//- rjf: threads left to enter > 0 => wait
if(threads_left_to_enter > 0)
if(n != 0)
{
// rjf: first try a spin loop
B32 done_waiting = 0;
ProfScope("spin loop wait") for(U64 spin_count = 0; spin_count < 10000; spin_count += 1)
{
if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
{
done_waiting = 1;
break;
}
}
U64 threads_left_to_enter = ins_atomic_u64_dec_eval(&n->threads_left_to_enter);

// rjf: not done waiting -> need to do slow wait on condition variable
if(!done_waiting) ProfScope("slow wait")
//- rjf: threads left to enter > 0 => wait
if(threads_left_to_enter > 0)
{
RWMutexScope(n->rw_mutex, 0) for(;;)
// rjf: first try a spin loop
B32 done_waiting = 0;
ProfScope("spin loop wait") for(U64 spin_count = 0; spin_count < 10000; spin_count += 1)
{
if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
{
done_waiting = 1;
break;
}
cond_var_wait_rw(n->cv, n->rw_mutex, 0, max_U64);
}

// rjf: not done waiting -> need to do slow wait on condition variable
if(!done_waiting) ProfScope("slow wait")
{
RWMutexScope(n->rw_mutex, 0) for(;;)
{
if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
{
break;
}
cond_var_wait_rw(n->cv, n->rw_mutex, 0, max_U64);
}
}

// rjf: decrement leave counter
if(ins_atomic_u64_dec_eval(&n->threads_left_to_leave) > 0)
{
ProfScope("signal") cond_var_signal(n->cv);
}
}

// rjf: decrement leave counter
if(ins_atomic_u64_dec_eval(&n->threads_left_to_leave) > 0)
//- rjf: threads left to enter == 0 -> last thread, wakeup
else
{
ins_atomic_u64_eval_assign(&n->threads_left_to_enter, n->count);
ProfScope("wake up") RWMutexScope(n->rw_mutex, 1)
{
ins_atomic_u64_eval_assign(&n->threads_left_to_leave, n->count-1);
}
ProfScope("signal") cond_var_signal(n->cv);
}
}

//- rjf: threads left to enter == 0 -> last thread, wakeup
else
{
ins_atomic_u64_eval_assign(&n->threads_left_to_enter, n->count);
ProfScope("wake up") RWMutexScope(n->rw_mutex, 1)
{
ins_atomic_u64_eval_assign(&n->threads_left_to_leave, n->count-1);
}
ProfScope("signal") cond_var_signal(n->cv);
}

//- rjf: wait for threads left to leave == 0
ProfScope("wait for threads to leave")
{
for(U64 spin_count = 0;; spin_count += 1)

//- rjf: wait for threads left to leave == 0
ProfScope("wait for threads to leave")
{
if(ins_atomic_u64_eval(&n->threads_left_to_leave) == 0)
for(U64 spin_count = 0;; spin_count += 1)
{
break;
if(ins_atomic_u64_eval(&n->threads_left_to_leave) == 0)
{
break;
}
}
}
}

ProfEnd();
}