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Fiasco.OC: fix race while pager_object destruction 

When the pager gets a pagefault, exception, pause, or wakeup request it's
always possible, that the corresponding thread gets destroyed between
receiving the message and looking up the thread's pager_object. This commit
unifies the check for a valid pager_object for each kind of requests to the
pager, thereby adds currently missing checks.
This commit is contained in:
Stefan Kalkowski 2012-03-27 11:13:53 +02:00 committed by Norman Feske
parent 75aba75ff8
commit ccebaa3802
1 changed files with 7 additions and 10 deletions
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17
base-foc/src/base/pager/pager.cc
View File

@ -55,14 +55,18 @@ void Pager_activation_base::entry()
continue;
}
/* lookup referenced object */
Pager_object *obj = _ep->obj_by_id(pager.badge());
/* the pager_object might be destroyed, while we got the message */
if (!obj)
continue;
switch (pager.msg_type()) {
case Ipc_pager::PAGEFAULT:
case Ipc_pager::EXCEPTION:
{
/* lookup referenced object */
Pager_object *obj = _ep->obj_by_id(pager.badge());
if (pager.is_exception()) {
Lock::Guard guard(obj->state.lock);
pager.copy_regs(&obj->state);
@ -94,11 +98,6 @@ void Pager_activation_base::entry()
* have to send a reply to the specified thread and answer the
* call.
*/
Pager_object *obj = _ep->obj_by_id(pager.badge());
if (!obj) {
PWRN("Got illegal wake-up message from %lx", pager.badge());
continue;
}
/* send reply to the caller */
pager.set_reply_dst(Native_thread());
@ -122,8 +121,6 @@ void Pager_activation_base::entry()
*/
case Ipc_pager::PAUSE:
{
Pager_object *obj = _ep->obj_by_id(pager.badge());
Lock::Guard guard(obj->state.lock);
pager.copy_regs(&obj->state);