From: "=?ISO-8859-1?B?cmVtYXBlcg==?=" <yp.fangdong@gmail.com>
To: "=?ISO-8859-1?B?bGludXgtZnNkZXZlbA==?=" 
	<linux-fsdevel@vger.kernel.org>,
        "=?ISO-8859-1?B?bGludXgta2VybmVs?=" <linux-kernel@vger.kernel.org>
Subject: generic_make_request not locked
Mime-Version: 1.0
Content-Type: text/plain;
	charset="ISO-8859-1"
Date: Tue, 30 Apr 2013 13:39:20 +0800
Message-ID: <tencent_0BD3EAC403C9DFE43143959B@qq.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Transfer-Encoding: 8bit
Content-Length: 1024
Lines: 24

/*
 * We only want one ->make_request_fn to be active at a time,
 * else stack usage with stacked devices could be a problem.
 * So use current->bio_list to keep a list of requests
 * submited by a make_request_fn function.
 * current->bio_list is also used as a flag to say if
 * generic_make_request is currently active in this task or not.
 * If it is NULL, then no make_request is active.  If it is non-NULL,
 * then a make_request is active, and new requests should be added
 * at the tail
 */
void generic_make_request(struct bio *bio)
{
...
    if (current->bio_list) {
        /* make_request is active */
        bio_list_add(current->bio_list, bio);
        return;
    }
...
}

current->bio_list is a global variable, and generic_make_request would run on multithread environment, so, i don't understand why here( bio_list_add ) not lock?
thx everybody.????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m????????????I?