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disallowed semaphore removal from a group when a process is waiting for the semaphore to be signaled

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This commit is contained in:
hyunghwan.chung
2017-11-03 16:26:55 +00:00
parent f7272c00fb
commit 27c2c5b404
4 changed files with 33 additions and 12 deletions
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31
moo/lib/exec.c
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@ -816,7 +816,7 @@ static MOO_INLINE void await_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
count = MOO_OOP_TO_SMOOI(sem->count);
if (count > 0)
{
/* it's already signalled */
/* it's already signaled */
count--;
sem->count = MOO_SMOOI_TO_OOP(count);
@ -881,7 +881,7 @@ static MOO_INLINE moo_oop_t await_semaphore_group (moo_t* moo, moo_oop_semaphore
}
/* no semaphores have been signaled. suspend the current process
* until the at least one of them is signaled */
* until at least one of them is signaled */
proc = moo->processor->active;
/* suspend the active process */
@ -2622,6 +2622,25 @@ static moo_pfrc_t pf_semaphore_group_remove_semaphore (moo_t* moo, moo_ooi_t nar
if (sem->group == rcv)
{
int sems_idx;
if ((moo_oop_t)rcv->waiting.first != moo->_nil)
{
/* there is a process waiting on this semaphore group.
* i don't allow a semaphore to be removed from the group.
* i want to dodge potential problems arising when removal is allowed.
*
* for instance, consider this psuedo code.
* sg addSemaphore: s
* [ sg wait ] fork.
* [ sg wait ] fork.
* [ sg wait ] fork.
* sg removeSemaphore: s.
*
*/
MOO_STACK_SETRETTOERROR (moo, nargs, MOO_EPERM);
goto done;
}
sems_idx = MOO_OOP_TO_SMOOI(sem->count) > 0? MOO_SEMAPHORE_GROUP_SEMS_SIG: MOO_SEMAPHORE_GROUP_SEMS_UNSIG;
MOO_DELETE_FROM_OOP_LIST (moo, &rcv->sems[sems_idx], sem, grm);
sem->grm.prev = (moo_oop_semaphore_t)moo->_nil;
@ -2632,6 +2651,7 @@ static moo_pfrc_t pf_semaphore_group_remove_semaphore (moo_t* moo, moo_ooi_t nar
{
moo_ooi_t count;
count = MOO_OOP_TO_SMOOI(rcv->sem_io_count);
MOO_ASSERT (moo, count > 0);
count--;
rcv->sem_io_count = MOO_SMOOI_TO_OOP(count);
}
@ -2644,6 +2664,7 @@ static moo_pfrc_t pf_semaphore_group_remove_semaphore (moo_t* moo, moo_ooi_t nar
MOO_STACK_SETRETTOERROR (moo, nargs, MOO_EPERM);
}
done:
return MOO_PF_SUCCESS;
}
@ -2666,7 +2687,7 @@ static moo_pfrc_t pf_semaphore_group_wait (moo_t* moo, moo_ooi_t nargs)
sem = await_semaphore_group (moo, (moo_oop_semaphore_group_t)rcv);
if (sem != moo->_nil)
{
/* there was a singaled semaphore. the active process won't get
/* there was a signaled semaphore. the active process won't get
* suspended. change the return value of the current process
* forcibly to the signaled semaphore */
MOO_STACK_SETTOP (moo, sem);
@ -4957,7 +4978,7 @@ static MOO_INLINE int switch_process_if_needed (moo_t* moo)
if (moo->sem_gcfin_sigreq)
{
signal_sem_gcfin:
MOO_LOG0 (moo, MOO_LOG_IC | MOO_LOG_DEBUG, "Signalled GCFIN semaphore\n");
MOO_LOG0 (moo, MOO_LOG_IC | MOO_LOG_DEBUG, "Signaled GCFIN semaphore\n");
proc = signal_semaphore (moo, moo->sem_gcfin);
if (moo->processor->active == moo->nil_process && (moo_oop_t)proc != moo->_nil)
@ -4998,7 +5019,7 @@ static MOO_INLINE int switch_process_if_needed (moo_t* moo)
*/
MOO_LOG3 (moo, MOO_LOG_IC | MOO_LOG_DEBUG,
"Signalled GCFIN semaphore without gcfin signal request - total - %zd runnable/running - %zd suspended - %zd\n",
"Signaled GCFIN semaphore without gcfin signal request - total - %zd runnable/running - %zd suspended - %zd\n",
MOO_OOP_TO_SMOOI(moo->processor->total_count), MOO_OOP_TO_SMOOI(moo->processor->runnable.count), MOO_OOP_TO_SMOOI(moo->processor->suspended.count));
proc = signal_semaphore (moo, moo->sem_gcfin);
if ((moo_oop_t)proc != moo->_nil)