[PATCH] elf_fdpic_core_dump: don't take tasklist_lock

Oleg Nesterov
2006-08-13T15:47:31Z

do_each_thread() is rcu-safe, and all tasks which use this ->mm must
sleep in wait_for_completion(&mm->core_done) at this point, so we can
use RCU locks.

Also, remove unneeded INIT_LIST_HEAD(new) before list_add(new, head).

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 2.6.18-rc3/fs/binfmt_elf_fdpic.c~fdpic 2006-07-16 01:53:08.000000000 +0400
+++ 2.6.18-rc3/fs/binfmt_elf_fdpic.c 2006-08-14 00:05:27.000000000 +0400
@@ -1597,20 +1597,19 @@ static int elf_fdpic_core_dump(long sign

if (signr) {
struct elf_thread_status *tmp;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
do_each_thread(g,p)
if (current->mm == p->mm && current != p) {
tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
if (!tmp) {
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
goto cleanup;
}
- INIT_LIST_HEAD(&tmp->list);
tmp->thread = p;
list_add(&tmp->list, &thread_list);
}
while_each_thread(g,p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
list_for_each(t, &thread_list) {
struct elf_thread_status *tmp;
int sz;