[Minios-devel] [UNIKRAFT PATCH v4 08/12] lib/uksched: Set scheduler reference only if adding the thread was successful

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Scheduler may reject adding threads if certain conditions are not met.
Therefore we set the scheduler reference only if adding the thread was
successful.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
 lib/uksched/include/uk/sched.h | 17 ++++++++++++-----
 lib/uksched/thread.c           |  1 +
 lib/ukschedcoop/schedcoop.c    |  4 +++-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/lib/uksched/include/uk/sched.h b/lib/uksched/include/uk/sched.h
index 9e218688..3eb1f4ec 100644
--- a/lib/uksched/include/uk/sched.h
+++ b/lib/uksched/include/uk/sched.h
@@ -59,7 +59,7 @@ int uk_sched_set_default(struct uk_sched *s);
 typedef void  (*uk_sched_yield_func_t)
                (struct uk_sched *s);
 
-typedef void  (*uk_sched_thread_add_func_t)
+typedef int   (*uk_sched_thread_add_func_t)
                (struct uk_sched *s, struct uk_thread *t,
                        const uk_thread_attr_t *attr);
 typedef void  (*uk_sched_thread_remove_func_t)
@@ -107,24 +107,31 @@ static inline void uk_sched_yield(void)
        s->yield(s);
 }
 
-static inline void uk_sched_thread_add(struct uk_sched *s,
+static inline int uk_sched_thread_add(struct uk_sched *s,
                struct uk_thread *t, const uk_thread_attr_t *attr)
 {
+       int rc;
+
        UK_ASSERT(s);
        UK_ASSERT(t);
        if (attr)
                t->detached = attr->detached;
-       t->sched = s;
-       s->thread_add(s, t, attr);
+       rc = s->thread_add(s, t, attr);
+       if (rc == 0)
+               t->sched = s;
+       return rc;
 }
 
-static inline void uk_sched_thread_remove(struct uk_sched *s,
+static inline int uk_sched_thread_remove(struct uk_sched *s,
                struct uk_thread *t)
 {
        UK_ASSERT(s);
        UK_ASSERT(t);
+       if (t->sched != s)
+               return -EINVAL;
        s->thread_remove(s, t);
        t->sched = NULL;
+       return 0;
 }
 
 static inline int uk_sched_thread_set_prio(struct uk_sched *s,
diff --git a/lib/uksched/thread.c b/lib/uksched/thread.c
index ff0fb39f..4d931a74 100644
--- a/lib/uksched/thread.c
+++ b/lib/uksched/thread.c
@@ -89,6 +89,7 @@ int uk_thread_init(struct uk_thread *thread,
        thread->wakeup_time = 0LL;
        thread->detached = false;
        uk_waitq_init(&thread->waiting_threads);
+       thread->sched = NULL;
 
 #ifdef CONFIG_HAVE_LIBC
        //TODO _REENT_INIT_PTR(&thread->reent);
diff --git a/lib/ukschedcoop/schedcoop.c b/lib/ukschedcoop/schedcoop.c
index a3f265c6..559df006 100644
--- a/lib/ukschedcoop/schedcoop.c
+++ b/lib/ukschedcoop/schedcoop.c
@@ -132,7 +132,7 @@ static void schedcoop_schedule(struct uk_sched *s)
        }
 }
 
-static void schedcoop_thread_add(struct uk_sched *s, struct uk_thread *t,
+static int schedcoop_thread_add(struct uk_sched *s, struct uk_thread *t,
        const uk_thread_attr_t *attr __unused)
 {
        unsigned long flags;
@@ -143,6 +143,8 @@ static void schedcoop_thread_add(struct uk_sched *s, struct 
uk_thread *t,
        flags = ukplat_lcpu_save_irqf();
        UK_TAILQ_INSERT_TAIL(&prv->thread_list, t, thread_list);
        ukplat_lcpu_restore_irqf(flags);
+
+       return 0;
 }
 
 static void schedcoop_thread_remove(struct uk_sched *s, struct uk_thread *t)
-- 
2.11.0


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