[PATCH] SRCU: report out-of-memory errors

Currently the init_srcu_struct() routine has no way to report out-of-memory errors. This patch (as761) makes it return -ENOMEM when the per-cpu data allocation fails. The patch also makes srcu_init_notifier_head() report a BUG if a notifier head can't be initialized. Perhaps it should return -ENOMEM instead, but in the most likely cases where this might occur I don't think any recovery is possible. Notifier chains generally are not created dynamically. [[email protected]: avoid statement-with-side-effect in macro] Signed-off-by: Alan Stern <[email protected]> Acked-by: Paul E. McKenney <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Oct 4, 2006 · e6a9201 · e6a9201
1 parent eabc069
commit e6a9201
Show file tree

Hide file tree

Showing 3 changed files with 6 additions and 4 deletions.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
@@ -43,7 +43,7 @@ struct srcu_struct {
 #define srcu_barrier()
 #endif /* #else #ifndef CONFIG_PREEMPT */
 
-void init_srcu_struct(struct srcu_struct *sp);
+int init_srcu_struct(struct srcu_struct *sp);
 void cleanup_srcu_struct(struct srcu_struct *sp);
 int srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
 void srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);

diff --git a/kernel/srcu.c b/kernel/srcu.c
@@ -42,11 +42,12 @@
  * to any other function.  Each srcu_struct represents a separate domain
  * of SRCU protection.
  */
-void init_srcu_struct(struct srcu_struct *sp)
+int init_srcu_struct(struct srcu_struct *sp)
 {
 	sp->completed = 0;
-	sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
 	mutex_init(&sp->mutex);
+	sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
+	return (sp->per_cpu_ref ? 0 : -ENOMEM);
 }
 
 /*

diff --git a/kernel/sys.c b/kernel/sys.c
@@ -517,7 +517,8 @@ EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
 void srcu_init_notifier_head(struct srcu_notifier_head *nh)
 {
 	mutex_init(&nh->mutex);
-	init_srcu_struct(&nh->srcu);
+	if (init_srcu_struct(&nh->srcu) < 0)
+		BUG();
 	nh->head = NULL;
 }