[PATCH 4.9 42/42] SUNRPC: use _bh spinlocking on ->transport_lock

[Greg Kroah-Hartman]

From: "NeilBrown" <neilb@xxxxxxx>

Prior to Linux 5.3, ->transport_lock in sunrpc required the _bh style
spinlocks (when not called from a bottom-half handler).

When upstream 3848e96edf4788f772d83990022fa7023a233d83 was backported to
stable kernels, the spin_lock/unlock calls should have been changed to
the _bh version, but this wasn't noted in the patch and didn't happen.

So convert these lock/unlock calls to the _bh versions.

This patch is required for any stable kernel prior to 5.3 to which the
above mentioned patch was backported.  Namely 4.9.y, 4.14.y, 4.19.y.

Signed-off-by: NeilBrown <neilb@xxxxxxx>
Reported-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
Reviewed-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
Tested-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
---
 net/sunrpc/xprt.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1451,9 +1451,9 @@ static void xprt_destroy(struct rpc_xprt
 	 * is cleared.  We use ->transport_lock to ensure the mod_timer()
 	 * can only run *before* del_time_sync(), never after.
 	 */
-	spin_lock(&xprt->transport_lock);
+	spin_lock_bh(&xprt->transport_lock);
 	del_timer_sync(&xprt->timer);
-	spin_unlock(&xprt->transport_lock);
+	spin_unlock_bh(&xprt->transport_lock);
 
 	rpc_xprt_debugfs_unregister(xprt);
 	rpc_destroy_wait_queue(&xprt->binding);