RDMA/addr: Fix race with netevent_callback()/rdma_addr_cancel()

This three thread race can result in the work being run once the callback
becomes NULL:

       CPU1                 CPU2                   CPU3
 netevent_callback()
                     process_one_req()       rdma_addr_cancel()
                      [..]
     spin_lock_bh()
  	set_timeout()
     spin_unlock_bh()

						spin_lock_bh()
						list_del_init(&req->list);
						spin_unlock_bh()

		     req->callback = NULL
		     spin_lock_bh()
		       if (!list_empty(&req->list))
                         // Skipped!
		         // cancel_delayed_work(&req->work);
		     spin_unlock_bh()

		    process_one_req() // again
		     req->callback() // BOOM
						cancel_delayed_work_sync()

The solution is to always cancel the work once it is completed so any
in between set_timeout() does not result in it running again.

Cc: [email protected]
Fixes: 44e75052bc2a ("RDMA/rdma_cm: Make rdma_addr_cancel into a fence")
Link: https://lore.kernel.org/r/[email protected]
Reported-by: Dan Aloni <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

0 files changed, 0 insertions, 0 deletions