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authorJosé Bollo <jose.bollo@iot.bzh>2018-12-04 12:05:01 +0100
committerJose Bollo <jose.bollo@iot.bzh>2018-12-05 10:08:10 +0100
commit3f2e3d9ee06073b4bdbfe0f0321574f66397505e (patch)
tree3dcd7c03c1341cef8d2bdb7986ad40b100dc8e7d
parent13a5afe7dbd698b2d85212cf4275858a1734a49e (diff)
afb-hook: Improve reentrancy of hooking
Work on testing showed that a deadlock was occuring in management of hooks. Change-Id: Ib51eb4f0b9ffc5d9dfe2770f2c3f8f47f262b60f Signed-off-by: José Bollo <jose.bollo@iot.bzh>
-rw-r--r--src/afb-hook.c289
1 files changed, 163 insertions, 126 deletions
diff --git a/src/afb-hook.c b/src/afb-hook.c
index 3d57ca52..3fcd36d0 100644
--- a/src/afb-hook.c
+++ b/src/afb-hook.c
@@ -116,8 +116,9 @@ struct afb_hook_global {
void *closure; /**< closure for callbacks */
};
-/* synchronisation across threads */
+/* synchronization across threads */
static pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
/* list of hooks for xreq */
static struct afb_hook_xreq *list_of_xreq_hooks = NULL;
@@ -171,24 +172,6 @@ static char *_pbuf_(const char *fmt, va_list args, char **palloc, char *sbuf, si
return sbuf;
}
-#if 0 /* old behaviour: use NOTICE */
-static void _hook_(const char *fmt1, const char *fmt2, va_list arg2, ...)
-{
- char *tag, *data, *mem1, *mem2, buf1[256], buf2[2000];
- va_list arg1;
-
- data = _pbuf_(fmt2, arg2, &mem2, buf2, sizeof buf2, NULL);
-
- va_start(arg1, arg2);
- tag = _pbuf_(fmt1, arg1, &mem1, buf1, sizeof buf1, NULL);
- va_end(arg1);
-
- NOTICE("[HOOK %s] %s", tag, data);
-
- free(mem1);
- free(mem2);
-}
-#else /* new behaviour: emits directly to stderr */
static void _hook_(const char *fmt1, const char *fmt2, va_list arg2, ...)
{
static const char chars[] = "HOOK: [] \n";
@@ -196,18 +179,23 @@ static void _hook_(const char *fmt1, const char *fmt2, va_list arg2, ...)
struct iovec iov[5];
va_list arg1;
+ /* "HOOK: [" */
iov[0].iov_base = (void*)&chars[0];
iov[0].iov_len = 7;
+ /* fmt1 ... */
va_start(arg1, arg2);
iov[1].iov_base = _pbuf_(fmt1, arg1, &mem1, buf1, sizeof buf1, &iov[1].iov_len);
va_end(arg1);
+ /* "] " */
iov[2].iov_base = (void*)&chars[7];
iov[2].iov_len = 2;
+ /* fmt2 arg2 */
iov[3].iov_base = _pbuf_(fmt2, arg2, &mem2, buf2, sizeof buf2, &iov[3].iov_len);
+ /* "\n" */
iov[4].iov_base = (void*)&chars[9];
iov[4].iov_len = 1;
@@ -216,7 +204,6 @@ static void _hook_(const char *fmt1, const char *fmt2, va_list arg2, ...)
free(mem1);
free(mem2);
}
-#endif
static void _hook_xreq_(const struct afb_xreq *xreq, const char *format, ...)
{
@@ -413,7 +400,8 @@ static struct afb_hook_xreq_itf hook_xreq_default_itf = {
init_hookid(&hookid); \
hook = list_of_xreq_hooks; \
while (hook) { \
- if (hook->itf->hook_xreq_##func \
+ if (hook->refcount \
+ && hook->itf->hook_xreq_##func \
&& (hook->flags & afb_hook_flag_req_##flag) != 0 \
&& (!hook->session || hook->session == xreq->context.session) \
&& MATCH_API(hook->api, xreq->request.called_api) \
@@ -569,10 +557,10 @@ struct json_object *afb_hook_xreq_get_client_info(const struct afb_xreq *xreq, s
void afb_hook_init_xreq(struct afb_xreq *xreq)
{
- static int reqindex;
+ static int reqindex = 0;
int f, flags;
- int add;
+ int add, x;
struct afb_hook_xreq *hook;
/* scan hook list to get the expected flags */
@@ -594,11 +582,10 @@ void afb_hook_init_xreq(struct afb_xreq *xreq)
/* store the hooking data */
xreq->hookflags = flags;
if (flags) {
- pthread_rwlock_wrlock(&rwlock);
- if (++reqindex < 0)
- reqindex = 1;
- xreq->hookindex = reqindex;
- pthread_rwlock_unlock(&rwlock);
+ do {
+ x = __atomic_load_n(&reqindex, __ATOMIC_RELAXED);
+ xreq->hookindex = (x + 1) % 1000000 ?: 1;
+ } while (x != __atomic_exchange_n(&reqindex, xreq->hookindex, __ATOMIC_RELAXED));
}
}
@@ -631,10 +618,10 @@ struct afb_hook_xreq *afb_hook_create_xreq(const char *api, const char *verb, st
hook->closure = closure;
/* record the hook */
- pthread_rwlock_wrlock(&rwlock);
+ pthread_mutex_lock(&mutex);
hook->next = list_of_xreq_hooks;
list_of_xreq_hooks = hook;
- pthread_rwlock_unlock(&rwlock);
+ pthread_mutex_unlock(&mutex);
/* returns it */
return hook;
@@ -642,31 +629,34 @@ struct afb_hook_xreq *afb_hook_create_xreq(const char *api, const char *verb, st
struct afb_hook_xreq *afb_hook_addref_xreq(struct afb_hook_xreq *hook)
{
- pthread_rwlock_wrlock(&rwlock);
- hook->refcount++;
- pthread_rwlock_unlock(&rwlock);
+ __atomic_add_fetch(&hook->refcount, 1, __ATOMIC_RELAXED);
return hook;
}
-void afb_hook_unref_xreq(struct afb_hook_xreq *hook)
+static void hook_clean_xreq()
{
- struct afb_hook_xreq **prv;
+ struct afb_hook_xreq **prv, *hook, *head;
- if (hook) {
- pthread_rwlock_wrlock(&rwlock);
- if (--hook->refcount)
- hook = NULL;
- else {
- /* unlink */
- prv = &list_of_xreq_hooks;
- while (*prv && *prv != hook)
+ if (pthread_rwlock_trywrlock(&rwlock) == 0) {
+ /* unlink under mutex */
+ head = NULL;
+ pthread_mutex_lock(&mutex);
+ prv = &list_of_xreq_hooks;
+ while ((hook = *prv)) {
+ if (hook->refcount)
prv = &(*prv)->next;
- if(*prv)
+ else {
*prv = hook->next;
+ hook->next = head;
+ head = hook;
+ }
}
+ pthread_mutex_unlock(&mutex);
pthread_rwlock_unlock(&rwlock);
- if (hook) {
- /* free */
+
+ /* free found hooks */
+ while((hook = head)) {
+ head = hook->next;
free(hook->api);
free(hook->verb);
if (hook->session)
@@ -676,6 +666,12 @@ void afb_hook_unref_xreq(struct afb_hook_xreq *hook)
}
}
+void afb_hook_unref_xreq(struct afb_hook_xreq *hook)
+{
+ if (hook && !__atomic_sub_fetch(&hook->refcount, 1, __ATOMIC_RELAXED))
+ hook_clean_xreq();
+}
+
/******************************************************************************
* section: default callbacks for tracing daemon interface
*****************************************************************************/
@@ -972,7 +968,8 @@ static struct afb_hook_api_itf hook_api_default_itf = {
init_hookid(&hookid); \
hook = list_of_api_hooks; \
while (hook) { \
- if (hook->itf->hook_api_##func \
+ if (hook->refcount \
+ && hook->itf->hook_api_##func \
&& (hook->flags & afb_hook_flag_api_##flag) != 0 \
&& MATCH_API(hook->api, apiname)) { \
hook->itf->hook_api_##func(hook->closure, &hookid, __VA_ARGS__); \
@@ -1245,10 +1242,10 @@ struct afb_hook_api *afb_hook_create_api(const char *api, int flags, struct afb_
hook->closure = closure;
/* record the hook */
- pthread_rwlock_wrlock(&rwlock);
+ pthread_mutex_lock(&mutex);
hook->next = list_of_api_hooks;
list_of_api_hooks = hook;
- pthread_rwlock_unlock(&rwlock);
+ pthread_mutex_unlock(&mutex);
/* returns it */
return hook;
@@ -1256,37 +1253,46 @@ struct afb_hook_api *afb_hook_create_api(const char *api, int flags, struct afb_
struct afb_hook_api *afb_hook_addref_api(struct afb_hook_api *hook)
{
- pthread_rwlock_wrlock(&rwlock);
- hook->refcount++;
- pthread_rwlock_unlock(&rwlock);
+ __atomic_add_fetch(&hook->refcount, 1, __ATOMIC_RELAXED);
return hook;
}
-void afb_hook_unref_api(struct afb_hook_api *hook)
+static void hook_clean_api()
{
- struct afb_hook_api **prv;
+ struct afb_hook_api **prv, *hook, *head;
- if (hook) {
- pthread_rwlock_wrlock(&rwlock);
- if (--hook->refcount)
- hook = NULL;
- else {
- /* unlink */
- prv = &list_of_api_hooks;
- while (*prv && *prv != hook)
+ if (pthread_rwlock_trywrlock(&rwlock) == 0) {
+ /* unlink under mutex */
+ head = NULL;
+ pthread_mutex_lock(&mutex);
+ prv = &list_of_api_hooks;
+ while ((hook = *prv)) {
+ if (hook->refcount)
prv = &(*prv)->next;
- if(*prv)
+ else {
*prv = hook->next;
+ hook->next = head;
+ head = hook;
+ }
}
+ pthread_mutex_unlock(&mutex);
pthread_rwlock_unlock(&rwlock);
- if (hook) {
- /* free */
+
+ /* free found hooks */
+ while((hook = head)) {
+ head = hook->next;
free(hook->api);
free(hook);
}
}
}
+void afb_hook_unref_api(struct afb_hook_api *hook)
+{
+ if (hook && !__atomic_sub_fetch(&hook->refcount, 1, __ATOMIC_RELAXED))
+ hook_clean_api();
+}
+
/******************************************************************************
* section: default callbacks for tracing service interface (evt)
*****************************************************************************/
@@ -1362,7 +1368,8 @@ static struct afb_hook_evt_itf hook_evt_default_itf = {
init_hookid(&hookid); \
hook = list_of_evt_hooks; \
while (hook) { \
- if (hook->itf->hook_evt_##what \
+ if (hook->refcount \
+ && hook->itf->hook_evt_##what \
&& (hook->flags & afb_hook_flag_evt_##what) != 0 \
&& MATCH_EVENT(hook->pattern, evt)) { \
hook->itf->hook_evt_##what(hook->closure, &hookid, __VA_ARGS__); \
@@ -1457,10 +1464,10 @@ struct afb_hook_evt *afb_hook_create_evt(const char *pattern, int flags, struct
hook->closure = closure;
/* record the hook */
- pthread_rwlock_wrlock(&rwlock);
+ pthread_mutex_lock(&mutex);
hook->next = list_of_evt_hooks;
list_of_evt_hooks = hook;
- pthread_rwlock_unlock(&rwlock);
+ pthread_mutex_unlock(&mutex);
/* returns it */
return hook;
@@ -1468,37 +1475,46 @@ struct afb_hook_evt *afb_hook_create_evt(const char *pattern, int flags, struct
struct afb_hook_evt *afb_hook_addref_evt(struct afb_hook_evt *hook)
{
- pthread_rwlock_wrlock(&rwlock);
- hook->refcount++;
- pthread_rwlock_unlock(&rwlock);
+ __atomic_add_fetch(&hook->refcount, 1, __ATOMIC_RELAXED);
return hook;
}
-void afb_hook_unref_evt(struct afb_hook_evt *hook)
+static void hook_clean_evt()
{
- struct afb_hook_evt **prv;
+ struct afb_hook_evt **prv, *hook, *head;
- if (hook) {
- pthread_rwlock_wrlock(&rwlock);
- if (--hook->refcount)
- hook = NULL;
- else {
- /* unlink */
- prv = &list_of_evt_hooks;
- while (*prv && *prv != hook)
+ if (pthread_rwlock_trywrlock(&rwlock) == 0) {
+ /* unlink under mutex */
+ head = NULL;
+ pthread_mutex_lock(&mutex);
+ prv = &list_of_evt_hooks;
+ while ((hook = *prv)) {
+ if (hook->refcount)
prv = &(*prv)->next;
- if(*prv)
+ else {
*prv = hook->next;
+ hook->next = head;
+ head = hook;
+ }
}
+ pthread_mutex_unlock(&mutex);
pthread_rwlock_unlock(&rwlock);
- if (hook) {
- /* free */
+
+ /* free found hooks */
+ while((hook = head)) {
+ head = hook->next;
free(hook->pattern);
free(hook);
}
}
}
+void afb_hook_unref_evt(struct afb_hook_evt *hook)
+{
+ if (hook && !__atomic_sub_fetch(&hook->refcount, 1, __ATOMIC_RELAXED))
+ hook_clean_evt();
+}
+
/******************************************************************************
* section: default callbacks for sessions (session)
*****************************************************************************/
@@ -1562,7 +1578,8 @@ static struct afb_hook_session_itf hook_session_default_itf = {
init_hookid(&hookid); \
hook = list_of_session_hooks; \
while (hook) { \
- if (hook->itf->hook_session_##what \
+ if (hook->refcount \
+ && hook->itf->hook_session_##what \
&& (hook->flags & afb_hook_flag_session_##what) != 0 \
&& MATCH_SESSION(hook->pattern, (sessid?:(sessid=afb_session_uuid(session))))) { \
hook->itf->hook_session_##what(hook->closure, &hookid, __VA_ARGS__); \
@@ -1629,10 +1646,10 @@ struct afb_hook_session *afb_hook_create_session(const char *pattern, int flags,
hook->closure = closure;
/* record the hook */
- pthread_rwlock_wrlock(&rwlock);
+ pthread_mutex_lock(&mutex);
hook->next = list_of_session_hooks;
list_of_session_hooks = hook;
- pthread_rwlock_unlock(&rwlock);
+ pthread_mutex_unlock(&mutex);
/* returns it */
return hook;
@@ -1640,37 +1657,46 @@ struct afb_hook_session *afb_hook_create_session(const char *pattern, int flags,
struct afb_hook_session *afb_hook_addref_session(struct afb_hook_session *hook)
{
- pthread_rwlock_wrlock(&rwlock);
- hook->refcount++;
- pthread_rwlock_unlock(&rwlock);
+ __atomic_add_fetch(&hook->refcount, 1, __ATOMIC_RELAXED);
return hook;
}
-void afb_hook_unref_session(struct afb_hook_session *hook)
+static void hook_clean_session()
{
- struct afb_hook_session **prv;
+ struct afb_hook_session **prv, *hook, *head;
- if (hook) {
- pthread_rwlock_wrlock(&rwlock);
- if (--hook->refcount)
- hook = NULL;
- else {
- /* unlink */
- prv = &list_of_session_hooks;
- while (*prv && *prv != hook)
+ if (pthread_rwlock_trywrlock(&rwlock) == 0) {
+ /* unlink under mutex */
+ head = NULL;
+ pthread_mutex_lock(&mutex);
+ prv = &list_of_session_hooks;
+ while ((hook = *prv)) {
+ if (hook->refcount)
prv = &(*prv)->next;
- if(*prv)
+ else {
*prv = hook->next;
+ hook->next = head;
+ head = hook;
+ }
}
+ pthread_mutex_unlock(&mutex);
pthread_rwlock_unlock(&rwlock);
- if (hook) {
- /* free */
+
+ /* free found hooks */
+ while((hook = head)) {
+ head = hook->next;
free(hook->pattern);
free(hook);
}
}
}
+void afb_hook_unref_session(struct afb_hook_session *hook)
+{
+ if (hook && !__atomic_sub_fetch(&hook->refcount, 1, __ATOMIC_RELAXED))
+ hook_clean_session();
+}
+
/******************************************************************************
* section: default callbacks for globals (global)
*****************************************************************************/
@@ -1716,7 +1742,8 @@ static struct afb_hook_global_itf hook_global_default_itf = {
init_hookid(&hookid); \
hook = list_of_global_hooks; \
while (hook) { \
- if (hook->itf->hook_global_##what \
+ if (hook->refcount \
+ && hook->itf->hook_global_##what \
&& (hook->flags & afb_hook_flag_global_##what) != 0) { \
hook->itf->hook_global_##what(hook->closure, &hookid, __VA_ARGS__); \
} \
@@ -1741,7 +1768,8 @@ static void update_global()
pthread_rwlock_rdlock(&rwlock);
hook = list_of_global_hooks;
while (hook) {
- flags = hook->flags;
+ if (hook->refcount)
+ flags = hook->flags;
hook = hook->next;
}
verbose_observer = (flags & afb_hook_flag_global_vverbose) ? afb_hook_global_vverbose : NULL;
@@ -1764,10 +1792,10 @@ struct afb_hook_global *afb_hook_create_global(int flags, struct afb_hook_global
hook->closure = closure;
/* record the hook */
- pthread_rwlock_wrlock(&rwlock);
+ pthread_mutex_lock(&mutex);
hook->next = list_of_global_hooks;
list_of_global_hooks = hook;
- pthread_rwlock_unlock(&rwlock);
+ pthread_mutex_unlock(&mutex);
/* update hooking */
update_global();
@@ -1778,36 +1806,45 @@ struct afb_hook_global *afb_hook_create_global(int flags, struct afb_hook_global
struct afb_hook_global *afb_hook_addref_global(struct afb_hook_global *hook)
{
- pthread_rwlock_wrlock(&rwlock);
- hook->refcount++;
- pthread_rwlock_unlock(&rwlock);
+ __atomic_add_fetch(&hook->refcount, 1, __ATOMIC_RELAXED);
return hook;
}
-void afb_hook_unref_global(struct afb_hook_global *hook)
+static void hook_clean_global()
{
- struct afb_hook_global **prv;
+ struct afb_hook_global **prv, *hook, *head;
- if (hook) {
- pthread_rwlock_wrlock(&rwlock);
- if (--hook->refcount)
- hook = NULL;
- else {
- /* unlink */
- prv = &list_of_global_hooks;
- while (*prv && *prv != hook)
+ if (pthread_rwlock_trywrlock(&rwlock) == 0) {
+ /* unlink under mutex */
+ head = NULL;
+ pthread_mutex_lock(&mutex);
+ prv = &list_of_global_hooks;
+ while ((hook = *prv)) {
+ if (hook->refcount)
prv = &(*prv)->next;
- if(*prv)
+ else {
*prv = hook->next;
+ hook->next = head;
+ head = hook;
+ }
}
+ pthread_mutex_unlock(&mutex);
pthread_rwlock_unlock(&rwlock);
- if (hook) {
- /* free */
- free(hook);
- /* update hooking */
- update_global();
+ /* free found hooks */
+ while((hook = head)) {
+ head = hook->next;
+ free(hook);
}
}
}
+void afb_hook_unref_global(struct afb_hook_global *hook)
+{
+ if (hook && !__atomic_sub_fetch(&hook->refcount, 1, __ATOMIC_RELAXED)) {
+ /* update hooking */
+ update_global();
+ hook_clean_global();
+ }
+}
+