Commit dfc428b6 authored Aug 03, 2011 by Oleg Nesterov Committed by Linus Torvalds Aug 03, 2011

taskstats: add_del_listener() shouldn't use the wrong node



1. Commit 26c4caea "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>

parent 12b3e038

kernel/taskstats.c

+7 −9

Original line number	Diff line number	Diff line
		@@ -291,30 +291,28 @@ static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
		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));
		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;
		}