On 2013/2/19 20:33, Zheng Liu wrote:

On Tue, Feb 19, 2013 at 09:22:40AM +0800, Li Zefan wrote:

quoted

There's a long long-standing bug...As long as I don't know when it dates
from.

I've written and attached a simple program to reproduce this bug, and it can
immediately trigger the bug in my box. It uses two threads, one keeps calling
read(), and the other calling readdir(), both on the same directory fd.

Hi Zefan,

Out of curiosity, why do you call read(2) on a directory fd?  I only
open(2) a directory in order to execute a flush operation to make sure
that a file is really created.

Because something wrong happened in userspace programs.

After a thread closed a socket, another thread is still reading data from
this socket, but the socket fd has been re-used for opening directory for
readdir()!