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

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1. Commit 26c4caea9d "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>
This commit is contained in:
Oleg Nesterov 2011-08-03 16:21:04 -07:00 committed by Linus Torvalds
parent 12b3e038e5
commit dfc428b656
1 changed files with 7 additions and 9 deletions
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16
kernel/taskstats.c
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@ -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)) if (!cpumask_subset(mask, cpu_possible_mask))
return -EINVAL; return -EINVAL;
s = NULL;
if (isadd == REGISTER) { if (isadd == REGISTER) {
for_each_cpu(cpu, mask) { for_each_cpu(cpu, mask) {
if (!s) s = kmalloc_node(sizeof(struct listener),
s = kmalloc_node(sizeof(struct listener), GFP_KERNEL, cpu_to_node(cpu));
GFP_KERNEL, cpu_to_node(cpu));
if (!s) if (!s)
goto cleanup; goto cleanup;
s->pid = pid; s->pid = pid;
INIT_LIST_HEAD(&s->list);
s->valid = 1; s->valid = 1;
listeners = &per_cpu(listener_array, cpu); listeners = &per_cpu(listener_array, cpu);
down_write(&listeners->sem); 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) if (s2->pid == pid)
goto next_cpu; goto exists;
} }
list_add(&s->list, &listeners->list); list_add(&s->list, &listeners->list);
s = NULL; s = NULL;
next_cpu: exists:
up_write(&listeners->sem); up_write(&listeners->sem);
kfree(s); /* nop if NULL */
} }
kfree(s);
return 0; return 0;
} }