RDMA/hfi1: Prevent use of lock before it is initialized

If there is a failure during probe of hfi1 before the sdma_map_lock is
initialized, the call to hfi1_free_devdata() will attempt to use a lock
that has not been initialized. If the locking correctness validator is on
then an INFO message and stack trace resembling the following may be seen:

  INFO: trying to register non-static key.
  The code is fine but needs lockdep annotation, or maybe
  you didn't initialize this object before use?
  turning off the locking correctness validator.
  Call Trace:
  register_lock_class+0x11b/0x880
  __lock_acquire+0xf3/0x7930
  lock_acquire+0xff/0x2d0
  _raw_spin_lock_irq+0x46/0x60
  sdma_clean+0x42a/0x660 [hfi1]
  hfi1_free_devdata+0x3a7/0x420 [hfi1]
  init_one+0x867/0x11a0 [hfi1]
  pci_device_probe+0x40e/0x8d0

The use of sdma_map_lock in sdma_clean() is for freeing the sdma_map
memory, and sdma_map is not allocated/initialized until after
sdma_map_lock has been initialized. This code only needs to be run if
sdma_map is not NULL, and so checking for that condition will avoid trying
to use the lock before it is initialized.

Fixes: 473291b ("IB/hfi1: Fix for early release of sdma context")
Fixes: 7724105 ("IB/hfi1: add driver files")
Link: https://lore.kernel.org/r/[email protected]
Reported-by: Zheyu Ma <[email protected]>
Signed-off-by: Douglas Miller <[email protected]>
Signed-off-by: Dennis Dalessandro <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

Author: drmiller-cni

drivers/infiniband/hw/hfi1/sdma.c

@@ -1288,11 +1288,13 @@ void sdma_clean(struct hfi1_devdata *dd, size_t num_engines)
 		kvfree(sde->tx_ring);
 		sde->tx_ring = NULL;
 	}
-	spin_lock_irq(&dd->sde_map_lock);
-	sdma_map_free(rcu_access_pointer(dd->sdma_map));
-	RCU_INIT_POINTER(dd->sdma_map, NULL);
-	spin_unlock_irq(&dd->sde_map_lock);
-	synchronize_rcu();
+	if (rcu_access_pointer(dd->sdma_map)) {
+		spin_lock_irq(&dd->sde_map_lock);
+		sdma_map_free(rcu_access_pointer(dd->sdma_map));
+		RCU_INIT_POINTER(dd->sdma_map, NULL);
+		spin_unlock_irq(&dd->sde_map_lock);
+		synchronize_rcu();
+	}
 	kfree(dd->per_sdma);
 	dd->per_sdma = NULL;