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

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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.

[akpm@osdl.org: avoid statement-with-side-effect in macro]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Alan Stern 2006-10-04 02:17:05 -07:00 committed by Linus Torvalds
parent eabc069401
commit e6a92013ba
3 changed files with 6 additions and 4 deletions
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2
include/linux/srcu.h
View file

@ -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);

5
kernel/srcu.c
View file

@ -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);
}
/*

3
kernel/sys.c
View file

@ -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;
}