From 04c26faa51d1e2fe71cf13c45791f5174c37f986 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 17 May 2021 02:28:58 +0800 Subject: tipc: wait and exit until all work queues are done 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 Signed-off-by: Xin Long Acked-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/core.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'net/tipc/core.h') diff --git a/net/tipc/core.h b/net/tipc/core.h index 03de7b213f55..5741ae488bb5 100644 --- a/net/tipc/core.h +++ b/net/tipc/core.h @@ -149,6 +149,8 @@ struct tipc_net { #endif /* Work item for net finalize */ struct tipc_net_work final_work; + /* The numbers of work queues in schedule */ + atomic_t wq_count; }; static inline struct tipc_net *tipc_net(struct net *net) -- cgit v1.2.3-59-g8ed1b