net/smc: no socket state changes in tasklet context

Several state changes occur during SMC socket closing. Currently
state changes triggered locally occur in process context with
lock_sock() taken while state changes triggered by peer occur in
tasklet context with bh_lock_sock() taken. bh_lock_sock() does not
wait till a lock_sock(() task in process context is finished. This
may lead to races in socket state transitions resulting in dangling
SMC-sockets, or it may lead to duplicate SMC socket freeing.
This patch introduces a closing worker to run all state changes under
lock_sock().

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/smc/smc_close.h b/net/smc/smc_close.h
index bc9a2df..4a3d99a 100644
--- a/net/smc/smc_close.h
+++ b/net/smc/smc_close.h
@@ -21,8 +21,8 @@
 void smc_close_wake_tx_prepared(struct smc_sock *smc);
 void smc_close_active_abort(struct smc_sock *smc);
 int smc_close_active(struct smc_sock *smc);
-void smc_close_passive_received(struct smc_sock *smc);
 void smc_close_sock_put_work(struct work_struct *work);
 int smc_close_shutdown_write(struct smc_sock *smc);
+void smc_close_init(struct smc_sock *smc);
 
 #endif /* SMC_CLOSE_H */