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-rw-r--r--src/jobs.c302
-rw-r--r--src/sig-monitor.c5
-rw-r--r--src/sig-monitor.h2
3 files changed, 184 insertions, 125 deletions
diff --git a/src/jobs.c b/src/jobs.c
index f2c9d52b..417f7eac 100644
--- a/src/jobs.c
+++ b/src/jobs.c
@@ -75,20 +75,20 @@ struct evloop
unsigned state; /**< encoded state */
int efd; /**< event notification */
struct sd_event *sdev; /**< the systemd event loop */
- pthread_cond_t cond; /**< condition */
struct fdev *fdev; /**< handling of events */
struct thread *holder; /**< holder of the evloop */
};
#define EVLOOP_STATE_WAIT 1U
#define EVLOOP_STATE_RUN 2U
-#define EVLOOP_STATE_LOCK 4U
/** Description of threads */
struct thread
{
struct thread *next; /**< next thread of the list */
struct thread *upper; /**< upper same thread */
+ struct thread *nholder;/**< next holder for evloop */
+ pthread_cond_t *cwhold;/**< condition wait for holding */
struct job *job; /**< currently processed job */
pthread_t tid; /**< the thread id */
volatile unsigned stop: 1; /**< stop requested */
@@ -96,7 +96,7 @@ struct thread
};
/**
- * Description of synchonous callback
+ * Description of synchronous callback
*/
struct sync
{
@@ -123,14 +123,13 @@ static int remains = 0; /** allowed count of waiting jobs */
/* list of threads */
static struct thread *threads;
static _Thread_local struct thread *current_thread;
-static _Thread_local struct evloop *current_evloop;
/* queue of pending jobs */
static struct job *first_job;
static struct job *free_jobs;
/* event loop */
-static struct evloop evloop[1];
+static struct evloop evloop;
#if defined(REMOVE_SYSTEMD_EVENT)
static struct fdev_epoll *fdevepoll;
@@ -300,13 +299,9 @@ static void evloop_run(int signum, void *arg)
{
int rc;
struct sd_event *se;
- struct evloop *el = arg;
if (!signum) {
- current_evloop = el;
- __atomic_store_n(&el->state, EVLOOP_STATE_LOCK|EVLOOP_STATE_RUN|EVLOOP_STATE_WAIT, __ATOMIC_RELAXED);
- __atomic_store_n(&el->holder, current_thread, __ATOMIC_RELAXED);
- se = el->sdev;
+ se = evloop.sdev;
rc = sd_event_prepare(se);
if (rc < 0) {
errno = -rc;
@@ -320,8 +315,7 @@ static void evloop_run(int signum, void *arg)
ERROR("sd_event_wait returned an error (state: %d): %m", sd_event_get_state(se));
}
}
- __atomic_and_fetch(&el->state, ~(EVLOOP_STATE_WAIT), __ATOMIC_RELAXED);
-
+ evloop.state = EVLOOP_STATE_RUN;
if (rc > 0) {
rc = sd_event_dispatch(se);
if (rc < 0) {
@@ -331,9 +325,93 @@ static void evloop_run(int signum, void *arg)
}
}
}
- __atomic_and_fetch(&el->state, ~(EVLOOP_STATE_WAIT|EVLOOP_STATE_RUN), __ATOMIC_RELAXED);
}
+/**
+ * Internal callback for evloop management.
+ * The effect of this function is hidden: it exits
+ * the waiting poll if any.
+ */
+static void evloop_on_efd_event()
+{
+ uint64_t x;
+ read(evloop.efd, &x, sizeof x);
+}
+
+/**
+ * wakeup the event loop if needed by sending
+ * an event.
+ */
+static void evloop_wakeup()
+{
+ uint64_t x;
+
+ if (evloop.state & EVLOOP_STATE_WAIT) {
+ x = 1;
+ write(evloop.efd, &x, sizeof x);
+ }
+}
+
+/**
+ * Release the currently held event loop
+ */
+static void evloop_release()
+{
+ struct thread *nh, *ct = current_thread;
+
+ if (evloop.holder == ct) {
+ nh = ct->nholder;
+ evloop.holder = nh;
+ if (nh)
+ pthread_cond_signal(nh->cwhold);
+ }
+}
+
+/**
+ * get the eventloop for the current thread
+ */
+static int evloop_get()
+{
+ struct thread *ct = current_thread;
+
+ if (evloop.holder)
+ return evloop.holder == ct;
+
+ ct->nholder = NULL;
+ evloop.holder = ct;
+ return 1;
+}
+
+/**
+ * acquire the eventloop for the current thread
+ */
+static void evloop_acquire()
+{
+ struct thread **pwait, *ct;
+ pthread_cond_t cond;
+
+ /* try to get the evloop */
+ if (!evloop_get()) {
+ /* failed, init waiting state */
+ ct = current_thread;
+ ct->nholder = NULL;
+ ct->cwhold = &cond;
+ pthread_cond_init(&cond, NULL);
+
+ /* queue current thread in holder list */
+ pwait = &evloop.holder;
+ while (*pwait)
+ pwait = &(*pwait)->nholder;
+ *pwait = ct;
+
+ /* wake up the evloop */
+ evloop_wakeup();
+
+ /* wait to acquire the evloop */
+ pthread_cond_wait(&cond, &mutex);
+ pthread_cond_destroy(&cond);
+ }
+}
#if defined(REMOVE_SYSTEMD_EVENT)
/**
@@ -363,9 +441,6 @@ static void thread_run(volatile struct thread *me)
{
struct thread **prv;
struct job *job;
-#if !defined(REMOVE_SYSTEMD_EVENT)
- struct evloop *el;
-#endif
/* initialize description of itself and link it in the list */
me->tid = pthread_self();
@@ -382,12 +457,8 @@ static void thread_run(volatile struct thread *me)
/* loop until stopped */
while (!me->stop) {
- /* release the event loop */
- if (current_evloop) {
- __atomic_and_fetch(&current_evloop->state, ~EVLOOP_STATE_LOCK, __ATOMIC_RELAXED);
- __atomic_store_n(&current_evloop->holder, NULL, __ATOMIC_RELAXED);
- current_evloop = NULL;
- }
+ /* release the current event loop */
+ evloop_release();
/* get a job */
job = job_get();
@@ -405,27 +476,31 @@ static void thread_run(volatile struct thread *me)
/* release the run job */
job_release(job);
#if !defined(REMOVE_SYSTEMD_EVENT)
- } else {
- /* no job, check events */
- el = &evloop[0];
- if (el->sdev && !__atomic_load_n(&el->state, __ATOMIC_RELAXED)) {
- /* run the events */
- __atomic_store_n(&el->state, EVLOOP_STATE_LOCK|EVLOOP_STATE_RUN|EVLOOP_STATE_WAIT, __ATOMIC_RELAXED);
- __atomic_store_n(&el->holder, me, __ATOMIC_RELAXED);
- current_evloop = el;
- pthread_mutex_unlock(&mutex);
- sig_monitor(0, evloop_run, el);
- pthread_mutex_lock(&mutex);
- } else {
- /* no job and not events */
- running--;
- if (!running)
- ERROR("Entering job deep sleep! Check your bindings.");
- me->waits = 1;
- pthread_cond_wait(&cond, &mutex);
- me->waits = 0;
- running++;
+
+
+
+ /* no job, check event loop wait */
+ } else if (evloop_get()) {
+ if (evloop.state != 0) {
+ /* busy ? */
+ CRITICAL("Can't enter dispatch while in dispatch!");
+ abort();
}
+ /* run the events */
+ evloop.state = EVLOOP_STATE_RUN|EVLOOP_STATE_WAIT;
+ pthread_mutex_unlock(&mutex);
+ sig_monitor(0, evloop_run, NULL);
+ pthread_mutex_lock(&mutex);
+ evloop.state = 0;
+ } else {
+ /* no job and no event loop */
+ running--;
+ if (!running)
+ ERROR("Entering job deep sleep! Check your bindings.");
+ me->waits = 1;
+ pthread_cond_wait(&cond, &mutex);
+ me->waits = 0;
+ running++;
#else
} else if (waitevt) {
/* no job and not events */
@@ -448,11 +523,7 @@ static void thread_run(volatile struct thread *me)
}
/* release the event loop */
- if (current_evloop) {
- __atomic_and_fetch(&current_evloop->state, ~EVLOOP_STATE_LOCK, __ATOMIC_RELAXED);
- __atomic_store_n(&el->holder, NULL, __ATOMIC_RELAXED);
- current_evloop = NULL;
- }
+ evloop_release();
/* unlink the current thread and cleanup */
prv = &threads;
@@ -659,41 +730,6 @@ int jobs_enter(
}
/**
- * Internal callback for evloop management.
- * The effect of this function is hidden: it exits
- * the waiting poll if any. Then it wakes up a thread
- * awaiting the evloop using signal.
- */
-static int on_evloop_efd(sd_event_source *s, int fd, uint32_t revents, void *userdata)
-{
- uint64_t x;
- struct evloop *evloop = userdata;
- read(evloop->efd, &x, sizeof x);
- pthread_mutex_lock(&mutex);
- pthread_cond_broadcast(&evloop->cond);
- pthread_mutex_unlock(&mutex);
- return 1;
-}
-
-/**
- * unlock the event loop if needed by sending
- * an event.
- * @param el the event loop to unlock
- * @param wait wait the unlocked state of the event loop
- */
-static void unlock_evloop(struct evloop *el, int wait)
-{
- /* wait for a modifiable event loop */
- while (__atomic_load_n(&el->state, __ATOMIC_RELAXED) & EVLOOP_STATE_WAIT) {
- uint64_t x = 1;
- write(el->efd, &x, sizeof x);
- if (!wait)
- break;
- pthread_cond_wait(&el->cond, &mutex);
- }
-}
-
-/**
* Unlocks the execution flow designed by 'jobloop'.
* @param jobloop indication of the flow to unlock
* @return 0 in case of success of -1 on error
@@ -701,7 +737,6 @@ static void unlock_evloop(struct evloop *el, int wait)
int jobs_leave(struct jobloop *jobloop)
{
struct thread *t;
- int i;
pthread_mutex_lock(&mutex);
t = threads;
@@ -713,15 +748,8 @@ int jobs_leave(struct jobloop *jobloop)
t->stop = 1;
if (t->waits)
pthread_cond_broadcast(&cond);
- else {
- i = (int)(sizeof evloop / sizeof *evloop);
- while(i) {
- if (evloop[--i].holder == t) {
- unlock_evloop(&evloop[i], 0);
- break;
- }
- }
- }
+ else
+ evloop_wakeup();
}
pthread_mutex_unlock(&mutex);
return -!t;
@@ -755,6 +783,18 @@ int jobs_call(
return do_sync(group, timeout, call_cb, &sync);
}
+/**
+ * Internal callback for evloop management.
+ * The effect of this function is hidden: it exits
+ * the waiting poll if any. Then it wakes up a thread
+ * awaiting the evloop using signal.
+ */
+static int on_evloop_efd(sd_event_source *s, int fd, uint32_t revents, void *userdata)
+{
+ evloop_on_efd_event();
+ return 1;
+}
+
/* temporary hack */
#if !defined(REMOVE_SYSTEMD_EVENT)
__attribute__((unused))
@@ -770,35 +810,33 @@ static void evloop_callback(void *arg, uint32_t event, struct fdev *fdev)
*/
static struct sd_event *get_sd_event_locked()
{
- struct evloop *el;
int rc;
/* creates the evloop on need */
- el = &evloop[0];
- if (!el->sdev) {
+ if (!evloop.sdev) {
/* start the creation */
- el->state = 0;
+ evloop.state = 0;
/* creates the eventfd for waking up polls */
- el->efd = eventfd(0, EFD_CLOEXEC);
- if (el->efd < 0) {
+ evloop.efd = eventfd(0, EFD_CLOEXEC|EFD_SEMAPHORE);
+ if (evloop.efd < 0) {
ERROR("can't make eventfd for events");
goto error1;
}
/* create the systemd event loop */
- rc = sd_event_new(&el->sdev);
+ rc = sd_event_new(&evloop.sdev);
if (rc < 0) {
ERROR("can't make new event loop");
goto error2;
}
/* put the eventfd in the event loop */
- rc = sd_event_add_io(el->sdev, NULL, el->efd, EPOLLIN, on_evloop_efd, el);
+ rc = sd_event_add_io(evloop.sdev, NULL, evloop.efd, EPOLLIN, on_evloop_efd, NULL);
if (rc < 0) {
ERROR("can't register eventfd");
#if !defined(REMOVE_SYSTEMD_EVENT)
- sd_event_unref(el->sdev);
- el->sdev = NULL;
+ sd_event_unref(evloop.sdev);
+ evloop.sdev = NULL;
error2:
- close(el->efd);
+ close(evloop.efd);
error1:
return NULL;
}
@@ -806,38 +844,27 @@ error1:
goto error3;
}
/* handle the event loop */
- el->fdev = fdev_epoll_add(get_fdevepoll(), sd_event_get_fd(el->sdev));
- if (!el->fdev) {
+ evloop.fdev = fdev_epoll_add(get_fdevepoll(), sd_event_get_fd(evloop.sdev));
+ if (!evloop.fdev) {
ERROR("can't create fdev");
error3:
- sd_event_unref(el->sdev);
+ sd_event_unref(evloop.sdev);
error2:
- close(el->efd);
+ close(evloop.efd);
error1:
- memset(el, 0, sizeof *el);
+ memset(&evloop, 0, sizeof evloop);
return NULL;
}
- fdev_set_autoclose(el->fdev, 0);
- fdev_set_events(el->fdev, EPOLLIN);
- fdev_set_callback(el->fdev, evloop_callback, el);
+ fdev_set_autoclose(evloop.fdev, 0);
+ fdev_set_events(evloop.fdev, EPOLLIN);
+ fdev_set_callback(evloop.fdev, evloop_callback, NULL);
#endif
}
- /* attach the event loop to the current thread */
- if (current_evloop != el) {
- if (current_evloop) {
- __atomic_and_fetch(&current_evloop->state, ~EVLOOP_STATE_LOCK, __ATOMIC_RELAXED);
- __atomic_store_n(&current_evloop->holder, NULL, __ATOMIC_RELAXED);
- }
- current_evloop = el;
- __atomic_or_fetch(&el->state, EVLOOP_STATE_LOCK, __ATOMIC_RELAXED);
- __atomic_store_n(&el->holder, current_thread, __ATOMIC_RELAXED);
- }
-
- /* wait for a modifiable event loop */
- unlock_evloop(el, 1);
+ /* acquire the event loop */
+ evloop_acquire();
- return el->sdev;
+ return evloop.sdev;
}
/**
@@ -847,11 +874,36 @@ error1:
struct sd_event *jobs_get_sd_event()
{
struct sd_event *result;
+ struct thread lt;
+
+ /* ensure an existing thread environment */
+ if (!current_thread) {
+ memset(&lt, 0, sizeof lt);
+ current_thread = &lt;
+ }
+ /* process */
pthread_mutex_lock(&mutex);
result = get_sd_event_locked();
pthread_mutex_unlock(&mutex);
+ /* release the faked thread environment if needed */
+ if (current_thread == &lt) {
+ /*
+ * Releasing it is needed because there is no way to guess
+ * when it has to be released really. But here is where it is
+ * hazardous: if the caller modifies the eventloop when it
+ * is waiting, there is no way to make the change effective.
+ * A workaround to achieve that goal is for the caller to
+ * require the event loop a second time after having modified it.
+ */
+ NOTICE("Requiring sd_event loop out of binder callbacks is hazardous!");
+ if (verbose_wants(Log_Level_Info))
+ sig_monitor_dumpstack();
+ evloop_release();
+ current_thread = NULL;
+ }
+
return result;
}
diff --git a/src/sig-monitor.c b/src/sig-monitor.c
index 15fe260d..9e13fa13 100644
--- a/src/sig-monitor.c
+++ b/src/sig-monitor.c
@@ -299,3 +299,8 @@ void sig_monitor(int timeout, void (*function)(int sig, void*), void *arg)
else
function(0, arg);
}
+
+void sig_monitor_dumpstack()
+{
+ return dumpstack(1, 0);
+}
diff --git a/src/sig-monitor.h b/src/sig-monitor.h
index 5fdac167..03c8ec49 100644
--- a/src/sig-monitor.h
+++ b/src/sig-monitor.h
@@ -25,3 +25,5 @@ extern int sig_monitor_enable();
extern void sig_monitor(int timeout, void (*function)(int sig, void*), void *arg);
+extern void sig_monitor_dumpstack();
+