bnxt_en: Fix netdev locking in ULP IRQ functions

netdev_lock is already held when calling bnxt_ulp_irq_stop() and
bnxt_ulp_irq_restart().  When converting rtnl_lock to netdev_lock,
the original code was rtnl_dereference() to indicate that rtnl_lock
was already held.  rcu_dereference_protected() is the correct
conversion after replacing rtnl_lock with netdev_lock.

Add a new helper netdev_lock_dereference() similar to
rtnl_dereference().

Fixes: 004b500 ("eth: bnxt: remove most dependencies on RTNL")
Reviewed-by: Andy Gospodarek <[email protected]>
Reviewed-by: Pavan Chebbi <[email protected]>
Signed-off-by: Michael Chan <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Michael Chan

drivers/net/ethernet/broadcom/bnxt/bnxt_ulp.c

@@ -20,6 +20,7 @@
 #include <asm/byteorder.h>
 #include <linux/bitmap.h>
 #include <linux/auxiliary_bus.h>
+#include <net/netdev_lock.h>
 
 #include "bnxt_hsi.h"
 #include "bnxt.h"
@@ -309,14 +310,12 @@ void bnxt_ulp_irq_stop(struct bnxt *bp)
 		if (!ulp->msix_requested)
 			return;
 
-		netdev_lock(bp->dev);
-		ops = rcu_dereference(ulp->ulp_ops);
+		ops = netdev_lock_dereference(ulp->ulp_ops, bp->dev);
 		if (!ops || !ops->ulp_irq_stop)
 			return;
 		if (test_bit(BNXT_STATE_FW_RESET_DET, &bp->state))
 			reset = true;
 		ops->ulp_irq_stop(ulp->handle, reset);
-		netdev_unlock(bp->dev);
 	}
 }
 
@@ -335,8 +334,7 @@ void bnxt_ulp_irq_restart(struct bnxt *bp, int err)
 		if (!ulp->msix_requested)
 			return;
 
-		netdev_lock(bp->dev);
-		ops = rcu_dereference(ulp->ulp_ops);
+		ops = netdev_lock_dereference(ulp->ulp_ops, bp->dev);
 		if (!ops || !ops->ulp_irq_restart)
 			return;
 
@@ -348,7 +346,6 @@ void bnxt_ulp_irq_restart(struct bnxt *bp, int err)
 			bnxt_fill_msix_vecs(bp, ent);
 		}
 		ops->ulp_irq_restart(ulp->handle, ent);
-		netdev_unlock(bp->dev);
 		kfree(ent);
 	}
 }

include/net/netdev_lock.h

@@ -98,6 +98,9 @@ static inline int netdev_lock_cmp_fn(const struct lockdep_map *a,
 				  &qdisc_xmit_lock_key);	\
 }
 
+#define netdev_lock_dereference(p, dev)				\
+	rcu_dereference_protected(p, lockdep_is_held(&(dev)->lock))
+
 int netdev_debug_event(struct notifier_block *nb, unsigned long event,
 		       void *ptr);