From 486ccb05fdbb7ca79784fdf0d07d2a86de48cf05 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 29 Sep 2006 02:00:24 -0700
Subject: [PATCH] [PATCH] elf_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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
fs/binfmt_elf.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index bb43da5cde5c3..6eb48e1446ecb 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -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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