net/smc: wait for pending work before clcsock release_sock

[ Upstream commit fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 ]

When the clcsock is already released using sock_release() and a pending
smc_listen_work accesses the clcsock than that will fail. Solve this
by canceling and waiting for the work to complete first. Because the
work holds the sock_lock it must make sure that the lock is not hold
before the new helper smc_clcsock_release() is invoked. And before the
smc_listen_work starts working check if the parent listen socket is
still valid, otherwise stop the work early.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5211c9729484 ("net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT")
Signed-off-by: Sasha Levin <sashal@kernel.org>