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Fix: compat_futex_noasync race condition
[userspace-rcu.git]
/
urcu-call-rcu-impl.h
diff --git
a/urcu-call-rcu-impl.h
b/urcu-call-rcu-impl.h
index f0751f538b4b66c829d4d988b0d5102192ad889b..c4a78752b5c383e4ade261c85051e18793bafa87 100644
(file)
--- a/
urcu-call-rcu-impl.h
+++ b/
urcu-call-rcu-impl.h
@@
-42,6
+42,7
@@
#include "urcu/list.h"
#include "urcu/futex.h"
#include "urcu/tls-compat.h"
#include "urcu/list.h"
#include "urcu/futex.h"
#include "urcu/tls-compat.h"
+#include "urcu/ref.h"
#include "urcu-die.h"
/* Data structure that identifies a call_rcu thread. */
#include "urcu-die.h"
/* Data structure that identifies a call_rcu thread. */
@@
-67,6
+68,7
@@
struct call_rcu_data {
struct call_rcu_completion {
int barrier_count;
int32_t futex;
struct call_rcu_completion {
int barrier_count;
int32_t futex;
+ struct urcu_ref ref;
};
struct call_rcu_completion_work {
};
struct call_rcu_completion_work {
@@
-667,10
+669,10
@@
void call_rcu(struct rcu_head *head,
struct call_rcu_data *crdp;
/* Holding rcu read-side lock across use of per-cpu crdp */
struct call_rcu_data *crdp;
/* Holding rcu read-side lock across use of per-cpu crdp */
- rcu_read_lock();
+
_
rcu_read_lock();
crdp = get_call_rcu_data();
_call_rcu(head, func, crdp);
crdp = get_call_rcu_data();
_call_rcu(head, func, crdp);
- rcu_read_unlock();
+
_
rcu_read_unlock();
}
/*
}
/*
@@
-768,6
+770,15
@@
void free_all_cpu_call_rcu_data(void)
free(crdp);
}
free(crdp);
}
+static
+void free_completion(struct urcu_ref *ref)
+{
+ struct call_rcu_completion *completion;
+
+ completion = caa_container_of(ref, struct call_rcu_completion, ref);
+ free(completion);
+}
+
static
void _rcu_barrier_complete(struct rcu_head *head)
{
static
void _rcu_barrier_complete(struct rcu_head *head)
{
@@
-776,8
+787,9
@@
void _rcu_barrier_complete(struct rcu_head *head)
work = caa_container_of(head, struct call_rcu_completion_work, head);
completion = work->completion;
work = caa_container_of(head, struct call_rcu_completion_work, head);
completion = work->completion;
- uatomic_dec(&completion->barrier_count);
- call_rcu_completion_wake_up(completion);
+ if (!uatomic_sub_return(&completion->barrier_count, 1))
+ call_rcu_completion_wake_up(completion);
+ urcu_ref_put(&completion->ref, free_completion);
free(work);
}
free(work);
}
@@
-787,19
+799,19
@@
void _rcu_barrier_complete(struct rcu_head *head)
void rcu_barrier(void)
{
struct call_rcu_data *crdp;
void rcu_barrier(void)
{
struct call_rcu_data *crdp;
- struct call_rcu_completion completion;
+ struct call_rcu_completion
*
completion;
int count = 0;
int was_online;
/* Put in offline state in QSBR. */
int count = 0;
int was_online;
/* Put in offline state in QSBR. */
- was_online = rcu_read_ongoing();
+ was_online =
_
rcu_read_ongoing();
if (was_online)
rcu_thread_offline();
/*
* Calling a rcu_barrier() within a RCU read-side critical
* section is an error.
*/
if (was_online)
rcu_thread_offline();
/*
* Calling a rcu_barrier() within a RCU read-side critical
* section is an error.
*/
- if (rcu_read_ongoing()) {
+ if (
_
rcu_read_ongoing()) {
static int warned = 0;
if (!warned) {
static int warned = 0;
if (!warned) {
@@
-809,12
+821,17
@@
void rcu_barrier(void)
goto online;
}
goto online;
}
+ completion = calloc(sizeof(*completion), 1);
+ if (!completion)
+ urcu_die(errno);
+
call_rcu_lock(&call_rcu_mutex);
cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
count++;
call_rcu_lock(&call_rcu_mutex);
cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
count++;
- completion.barrier_count = count;
- completion.futex = 0;
+ /* Referenced by rcu_barrier() and each call_rcu thread. */
+ urcu_ref_set(&completion->ref, count + 1);
+ completion->barrier_count = count;
cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
struct call_rcu_completion_work *work;
cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
struct call_rcu_completion_work *work;
@@
-822,20
+839,23
@@
void rcu_barrier(void)
work = calloc(sizeof(*work), 1);
if (!work)
urcu_die(errno);
work = calloc(sizeof(*work), 1);
if (!work)
urcu_die(errno);
- work->completion =
&
completion;
+ work->completion = completion;
_call_rcu(&work->head, _rcu_barrier_complete, crdp);
}
call_rcu_unlock(&call_rcu_mutex);
/* Wait for them */
for (;;) {
_call_rcu(&work->head, _rcu_barrier_complete, crdp);
}
call_rcu_unlock(&call_rcu_mutex);
/* Wait for them */
for (;;) {
- uatomic_dec(&completion
.
futex);
+ uatomic_dec(&completion
->
futex);
/* Decrement futex before reading barrier_count */
cmm_smp_mb();
/* Decrement futex before reading barrier_count */
cmm_smp_mb();
- if (!uatomic_read(&completion
.
barrier_count))
+ if (!uatomic_read(&completion
->
barrier_count))
break;
break;
- call_rcu_completion_wait(
&
completion);
+ call_rcu_completion_wait(completion);
}
}
+
+ urcu_ref_put(&completion->ref, free_completion);
+
online:
if (was_online)
rcu_thread_online();
online:
if (was_online)
rcu_thread_online();
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