Changeset d70fc74 in mainline for kernel/generic/src/smp/smp_call.c

Timestamp:

2012-07-06T12:58:58Z (13 years ago)

Author:

Adam Hraska <adam.hraska+hos@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

ef1603b

Parents:

1f8c11f

Message:

smp_call: Minor fixes and comments.

File:

• kernel/generic/src/smp/smp_call.c (modified) (5 diffs)

kernel/generic/src/smp/smp_call.c

@@ -54 +54 @@
  * 
  * If @a cpu_id is the local CPU, the function will be invoked
- * directly.
+ * directly. If the destination cpu id @a cpu_id is invalid
+ * or denotes an inactive cpu, the call is discarded immediately.
  * 
  * Interrupts must be enabled. Otherwise you run the risk
  * of a deadlock.
  * 
- * @param cpu_id Destination CPU's logical id (eg CPU->id)
+ * @param cpu_id Destination CPU's logical id (eg CPU->id).
  * @param func Function to call.
  * @param arg Argument to pass to the user supplied function @a func.
@@ -73 +74 @@
         
         /* Discard invalid calls. */
-        if (config.cpu_count <= cpu_id) {
+        if (config.cpu_count <= cpu_id || !cpus[cpu_id].active) {
                 call_start(call_info, func, arg);
                 call_done(call_info);
@@ -81 +82 @@
         /* Protect cpu->id against migration. */
         preemption_disable();
-        
+
         call_start(call_info, func, arg);
         
@@ -89 +90 @@
                 list_append(&call_info->calls_link, &cpus[cpu_id].smp_pending_calls);
                 spinlock_unlock(&cpus[cpu_id].smp_calls_lock);
-                                
+
+                /*
+                 * If a platform supports SMP it must implement arch_smp_call_ipi().
+                 * It should issue an IPI an cpu_id and invoke smp_call_ipi_recv()
+                 * on cpu_id in turn. 
+                 * 
+                 * Do not implement as just an empty dummy function. Instead
+                 * consider providing a full implementation or at least a version 
+                 * that panics if invoked. Note that smp_call_async() never
+                 * calls arch_smp_call_ipi() on uniprocessors even if CONFIG_SMP.
+                 */
                 arch_smp_call_ipi(cpu_id);
 #endif
@@ -131 +142 @@
 /** Architecture independent smp call IPI handler.
  * 
- * Interrupts must be disabled.
+ * Interrupts must be disabled. Tolerates spurious calls.
  */
 void smp_call_ipi_recv(void)