Changeset 472 for trunk/kernel/kern

Timestamp:

Aug 21, 2018, 5:58:40 PM (6 years ago)

Author:

alain

Message:

Fix the bug found by Axel in the process_register_thread() function

This function must use a busy-waiting lock when the thread is the IDLE_THREAD,
because we cennot use a descheduling policy when the IDLE_THREAD desriptor
is not initialised.

File:

• trunk/kernel/kern/process.c (modified) (3 diffs)

trunk/kernel/kern/process.c

@@ -1040 +1040 @@
                                  trdid_t   * trdid )
 {
-    ltid_t   ltid;
-    bool_t   found = false;
+    ltid_t         ltid;
+    thread_type_t  type;
+    reg_t          save_sr;
+    bool_t         found = false;
+ 
 
     assert( (process != NULL) , __FUNCTION__ , "process argument is NULL" );
@@ -1047 +1050 @@
     assert( (thread != NULL) , __FUNCTION__ , "thread argument is NULL" );
 
-    // take lock protecting th_tbl
-    spinlock_lock( &process->th_lock );
+    // take lock protecting th_tbl, depending on thread type:
+    // we don't want to use a descheduling policy for idle thread initialisation
+    if( type == THREAD_IDLE )  spinlock_lock_busy( &process->th_lock , &save_sr );
+    else                       spinlock_lock( &process->th_lock );
 
     // search a free slot in th_tbl[] 
@@ -1072 +1077 @@
     // release lock protecting th_tbl
     hal_fence();
-    spinlock_unlock( &process->th_lock );
+    if( type == THREAD_IDLE )  spinlock_unlock_busy( &process->th_lock , save_sr );
+    else                       spinlock_unlock( &process->th_lock );
 
     return (found) ? 0 : ENOMEM;