Changeset 592 for trunk/kernel/kern/scheduler.c

Timestamp:

Nov 1, 2018, 7:27:14 PM (6 years ago)

Author:

alain

Message:

Simplify the sched_handle°signals() function:
The rwlock protecting the process th_tbl[]
is no more used when handling a THREAD_DELETE request.

File:

• trunk/kernel/kern/scheduler.c (modified) (8 diffs)

trunk/kernel/kern/scheduler.c

@@ -145 +145 @@
 
 ////////////////////////////////////////////////////////////////////////////////////////////
-// This static function is the only function that can actually delete a thread.
+// This static function is the only function that can actually delete a thread,
+// and the associated process descriptor, if required.
 // It is private, because it is called by the sched_yield() public function.
 // It scan all threads attached to a given scheduler, and executes the relevant
 // actions for two types of pending requests: 
+//
 // - REQ_ACK : it checks that target thread is blocked, decrements the response counter
 //   to acknowledge the client thread, and reset the pending request. 
@@ -177 +179 @@
     sched = &core->scheduler;
 
+    // take the lock protecting sheduler state
+    busylock_acquire( &sched->lock );
+
     ////// scan user threads to handle both ACK and DELETE requests
     root = &sched->u_root;
@@ -193 +198 @@
 
 // check thread blocked
-assert( (thread->blocked & THREAD_BLOCKED_GLOBAL) , 
-"thread not blocked" );
+assert( (thread->blocked & THREAD_BLOCKED_GLOBAL) , "thread not blocked" );
  
             // decrement response counter
@@ -211 +215 @@
             // get thread ltid
             ltid = LTID_FROM_TRDID( thread->trdid);
-
-            // take the lock protecting th_tbl[]
-            rwlock_wr_acquire( &process->th_lock );
-
-            // take the lock protecting sheduler state
-            busylock_acquire( &sched->lock );
 
             // update scheduler state
@@ -238 +236 @@
             }
 
-            // release the lock protecting sheduler state
-            busylock_release( &sched->lock );
-
-            // get number of threads in local process
-            count = process->th_nr;
-
 // check th_nr value
-assert( (count > 0) , "process th_nr cannot be 0\n" );
+assert( (process->th_nr > 0) , "process th_nr cannot be 0\n" );
 
             // remove thread from process th_tbl[]
             process->th_tbl[ltid] = NULL;
-            process->th_nr = count - 1;
+            hal_atomic_add( &process->th_nr , - 1 );
  
-            // release the lock protecting th_tbl[]
-            rwlock_wr_release( &process->th_lock );
-
             // release memory allocated for thread descriptor
             thread_destroy( thread );
@@ -299 +288 @@
             // get thread ltid
             ltid = LTID_FROM_TRDID( thread->trdid);
-
-            // take the lock protecting th_tbl[]
-            rwlock_wr_acquire( &process_zero.th_lock );
-
-            // take lock protecting sheduler state
-            busylock_acquire( &sched->lock );
 
             // update scheduler state
@@ -326 +309 @@
             }
 
-            // release lock protecting scheduler state
-            busylock_release( &sched->lock );
-
             // get number of threads in local kernel process
             count = process_zero.th_nr;
 
 // check th_nr value
-assert( (count > 0) , "kernel process th_nr cannot be 0\n" );
+assert( (process_zero.th_nr > 0) , "kernel process th_nr cannot be 0\n" );
 
             // remove thread from process th_tbl[]
             process_zero.th_tbl[ltid] = NULL;
-            process_zero.th_nr = count - 1;
+            hal_atomic_add( &process_zero.th_nr , - 1 );
  
-            // release the lock protecting th_tbl[]
-            rwlock_wr_release( &process_zero.th_lock );
-
             // delete thread descriptor
             thread_destroy( thread );
@@ -353 +330 @@
         }
     }
+
+    // release the lock protecting sheduler state
+    busylock_release( &sched->lock );
+
 } // end sched_handle_signals()