04c26faa51
On some host, a crash could be triggered simply by repeating these
commands several times:
# modprobe tipc
# tipc bearer enable media udp name UDP1 localip 127.0.0.1
# rmmod tipc
[] BUG: unable to handle kernel paging request at ffffffffc096bb00
[] Workqueue: events 0xffffffffc096bb00
[] Call Trace:
[] ? process_one_work+0x1a7/0x360
[] ? worker_thread+0x30/0x390
[] ? create_worker+0x1a0/0x1a0
[] ? kthread+0x116/0x130
[] ? kthread_flush_work_fn+0x10/0x10
[] ? ret_from_fork+0x35/0x40
When removing the TIPC module, the UDP tunnel sock will be delayed to
release in a work queue as sock_release() can't be done in rtnl_lock().
If the work queue is schedule to run after the TIPC module is removed,
kernel will crash as the work queue function cleanup_beareri() code no
longer exists when trying to invoke it.
To fix it, this patch introduce a member wq_count in tipc_net to track
the numbers of work queues in schedule, and wait and exit until all
work queues are done in tipc_exit_net().
Fixes: d0f91938bede ("tipc: add ip/udp media type")
Reported-by: Shuang Li <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.