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Fiasco.OC: make capability ref-counter thread-safe

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Introduce process global spin-lock for Cap_index's reference-counter
to avoid non-atomic increment/decrement of the counter. Here, we don't
use a static Spinlock object, because it's constructor wouldn't be
initialized before used for the first time.
This commit is contained in:
Stefan Kalkowski 2012-05-29 11:14:53 +02:00 committed by Christian Helmuth
parent 94e14ec20b
commit 54e08cfed5
2 changed files with 26 additions and 2 deletions
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4
base-foc/include/base/cap_map.h
View File

@ -64,8 +64,8 @@ namespace Genode
bool used() const { return _id != UNUSED; }
uint16_t id() const { return _id; }
void id(uint16_t id) { _id = id; }
uint8_t inc() { return ++_ref_cnt; }
uint8_t dec() { return --_ref_cnt; }
uint8_t inc();
uint8_t dec();
addr_t kcap();
void* operator new (size_t size, Cap_index* idx) { return idx; }

24
base-foc/src/base/env/cap_map.cc vendored
View File

@ -18,6 +18,9 @@
#include <util/assert.h>
/* Lock implementation local include */
#include <spin_lock.h>
namespace Fiasco {
#include <l4/sys/consts.h>
#include <l4/sys/task.h>
@ -28,6 +31,9 @@ namespace Fiasco {
** Cap_index class **
***********************/
static volatile int _cap_index_spinlock = SPINLOCK_UNLOCKED;
bool Genode::Cap_index::higher(Genode::Cap_index *n) { return n->_id > _id; }
@ -46,6 +52,24 @@ Genode::addr_t Genode::Cap_index::kcap() {
return cap_idx_alloc()->idx_to_kcap(this); }
Genode::uint8_t Genode::Cap_index::inc()
{
spinlock_lock(&_cap_index_spinlock);
Genode::uint8_t ret = ++_ref_cnt;
spinlock_unlock(&_cap_index_spinlock);
return ret;
}
Genode::uint8_t Genode::Cap_index::dec()
{
spinlock_lock(&_cap_index_spinlock);
Genode::uint8_t ret = --_ref_cnt;
spinlock_unlock(&_cap_index_spinlock);
return ret;
}
/****************************
** Capability_map class **
****************************/