[PATCH for-next 1/6] RDMA/hfi1: Prevent use of lock before it is initialized

[Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>]

From: Douglas Miller <doug.miller@cornelisnetworks.com>

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: 473291b3ea0e1 ("IB/hfi1: Fix for early release of sdma context")
Fixes: 7724105686e71 ("IB/hfi1: add driver files")

Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Douglas Miller <doug.miller@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
---
 drivers/infiniband/hw/hfi1/sdma.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index f07d328..a95b654 100644
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/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;