patch-2.4.21 linux-2.4.21/kernel/sched.c

• Lines: 63
• Date: 2003-06-13 07:51:39.000000000 -0700
• Orig file: linux-2.4.20/kernel/sched.c
• Orig date: 2002-11-28 15:53:15.000000000 -0800

diff -urN linux-2.4.20/kernel/sched.c linux-2.4.21/kernel/sched.c
@@ -116,7 +116,7 @@
 
 #define idle_task(cpu) (init_tasks[cpu_number_map(cpu)])
 #define can_schedule(p,cpu) \
-	((p)->cpus_runnable & (p)->cpus_allowed & (1 << cpu))
+	((p)->cpus_runnable & (p)->cpus_allowed & (1UL << cpu))
 
 #else
 
@@ -359,7 +359,7 @@
 	if (task_on_runqueue(p))
 		goto out;
 	add_to_runqueue(p);
-	if (!synchronous || !(p->cpus_allowed & (1 << smp_processor_id())))
+	if (!synchronous || !(p->cpus_allowed & (1UL << smp_processor_id())))
 		reschedule_idle(p);
 	success = 1;
 out:
@@ -850,6 +850,44 @@
 
 void scheduling_functions_end_here(void) { }
 
+#if CONFIG_SMP
+/**
+ * set_cpus_allowed() - change a given task's processor affinity
+ * @p: task to bind
+ * @new_mask: bitmask of allowed processors
+ *
+ * Upon return, the task is running on a legal processor.  Note the caller
+ * must have a valid reference to the task: it must not exit() prematurely.
+ * This call can sleep; do not hold locks on call.
+ */
+void set_cpus_allowed(struct task_struct *p, unsigned long new_mask)
+{
+	new_mask &= cpu_online_map;
+	BUG_ON(!new_mask);
+
+	p->cpus_allowed = new_mask;
+
+	/*
+	 * If the task is on a no-longer-allowed processor, we need to move
+	 * it.  If the task is not current, then set need_resched and send
+	 * its processor an IPI to reschedule.
+	 */
+	if (!(p->cpus_runnable & p->cpus_allowed)) {
+		if (p != current) {
+			p->need_resched = 1;
+			smp_send_reschedule(p->processor);
+		}
+		/*
+		 * Wait until we are on a legal processor.  If the task is
+		 * current, then we should be on a legal processor the next
+		 * time we reschedule.  Otherwise, we need to wait for the IPI.
+		 */
+		while (!(p->cpus_runnable & p->cpus_allowed))
+			schedule();
+	}
+}
+#endif /* CONFIG_SMP */
+
 #ifndef __alpha__
 
 /*