[PATCH] elf_fdpic_core_dump: don't take tasklist_lock
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> Acked-By: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -1597,20 +1597,19 @@ static int elf_fdpic_core_dump(long signr, struct pt_regs *regs,
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if (signr) {
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if (signr) {
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struct elf_thread_status *tmp;
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struct elf_thread_status *tmp;
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read_lock(&tasklist_lock);
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rcu_read_lock();
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do_each_thread(g,p)
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do_each_thread(g,p)
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if (current->mm == p->mm && current != p) {
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if (current->mm == p->mm && current != p) {
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tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
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tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
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if (!tmp) {
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if (!tmp) {
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read_unlock(&tasklist_lock);
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rcu_read_unlock();
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goto cleanup;
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goto cleanup;
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}
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}
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INIT_LIST_HEAD(&tmp->list);
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tmp->thread = p;
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tmp->thread = p;
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list_add(&tmp->list, &thread_list);
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list_add(&tmp->list, &thread_list);
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}
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}
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while_each_thread(g,p);
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while_each_thread(g,p);
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read_unlock(&tasklist_lock);
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rcu_read_unlock();
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list_for_each(t, &thread_list) {
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list_for_each(t, &thread_list) {
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struct elf_thread_status *tmp;
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struct elf_thread_status *tmp;
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int sz;
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int sz;
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