taskstats: add_del_listener() shouldn't use the wrong node
1. Commit 26c4caea9d69 "don't allow duplicate entries in listener mode"
changed add_del_listener(REGISTER) so that "next_cpu:" can reuse the
listener allocated for the previous cpu, this doesn't look exactly
right even if minor.
Change the code to kfree() in the already-registered case, this case
is unlikely anyway so the extra kmalloc_node() shouldn't hurt but
looke more correct and clean.
2. use the plain list_for_each_entry() instead of _safe() to scan
listeners->list.
3. Remove the unneeded INIT_LIST_HEAD(&s->list), we are going to
list_add(&s->list).
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index d1db288..a09a549 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -291,30 +291,28 @@
if (!cpumask_subset(mask, cpu_possible_mask))
return -EINVAL;
- s = NULL;
if (isadd == REGISTER) {
for_each_cpu(cpu, mask) {
- if (!s)
- s = kmalloc_node(sizeof(struct listener),
- GFP_KERNEL, cpu_to_node(cpu));
+ s = kmalloc_node(sizeof(struct listener),
+ GFP_KERNEL, cpu_to_node(cpu));
if (!s)
goto cleanup;
+
s->pid = pid;
- INIT_LIST_HEAD(&s->list);
s->valid = 1;
listeners = &per_cpu(listener_array, cpu);
down_write(&listeners->sem);
- list_for_each_entry_safe(s2, tmp, &listeners->list, list) {
+ list_for_each_entry(s2, &listeners->list, list) {
if (s2->pid == pid)
- goto next_cpu;
+ goto exists;
}
list_add(&s->list, &listeners->list);
s = NULL;
-next_cpu:
+exists:
up_write(&listeners->sem);
+ kfree(s); /* nop if NULL */
}
- kfree(s);
return 0;
}