[PATCH] elf_core_dump: don't take tasklist_lock (486ccb05) · Commits · 戴 / test

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> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

fs/binfmt_elf.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -1479,20 +1479,19 @@ static int elf_core_dump(long signr, struct pt_regs regs, struct file file)

		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;

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