IB/core: Fix two kernel warnings triggered by rxe registration

Eliminate the WARN_ONs that create following two warnings when
registering an rxe device:

WARNING: CPU: 2 PID: 1005 at drivers/infiniband/core/device.c:449 ib_register_device+0x591/0x640 [ib_core]
CPU: 2 PID: 1005 Comm: run_tests Not tainted 4.15.0-rc4-dbg+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:ib_register_device+0x591/0x640 [ib_core]
Call Trace:
 rxe_register_device+0x3c6/0x470 [rdma_rxe]
 rxe_add+0x543/0x5e0 [rdma_rxe]
 rxe_net_add+0x37/0xb0 [rdma_rxe]
 rxe_param_set_add+0x5a/0x120 [rdma_rxe]
 param_attr_store+0x5e/0xc0
 module_attr_store+0x19/0x30
 sysfs_kf_write+0x3d/0x50
 kernfs_fop_write+0x116/0x1a0
 __vfs_write+0x23/0x120
 vfs_write+0xbe/0x1b0
 SyS_write+0x44/0xa0
 entry_SYSCALL_64_fastpath+0x23/0x9a

WARNING: CPU: 2 PID: 1005 at drivers/infiniband/core/sysfs.c:1279 ib_device_register_sysfs+0x11d/0x160 [ib_core]
CPU: 2 PID: 1005 Comm: run_tests Tainted: G        W        4.15.0-rc4-dbg+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:ib_device_register_sysfs+0x11d/0x160 [ib_core]
Call Trace:
 ib_register_device+0x3f7/0x640 [ib_core]
 rxe_register_device+0x3c6/0x470 [rdma_rxe]
 rxe_add+0x543/0x5e0 [rdma_rxe]
 rxe_net_add+0x37/0xb0 [rdma_rxe]
 rxe_param_set_add+0x5a/0x120 [rdma_rxe]
 param_attr_store+0x5e/0xc0
 module_attr_store+0x19/0x30
 sysfs_kf_write+0x3d/0x50
 kernfs_fop_write+0x116/0x1a0
 __vfs_write+0x23/0x120
 vfs_write+0xbe/0x1b0
 SyS_write+0x44/0xa0
 entry_SYSCALL_64_fastpath+0x23/0x9a

The code should accept either a parent pointer or a fully specified DMA
specification without producing warnings.

Fixes: 99db949403 ("IB/core: Remove ib_device.dma_device")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: stable@vger.kernel.org # v4.11
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/device.c

@@ -446,7 +446,6 @@ int ib_register_device(struct ib_device *device,
 	struct ib_udata uhw = {.outlen = 0, .inlen = 0};
 	struct device *parent = device->dev.parent;
 
-	WARN_ON_ONCE(!parent);
 	WARN_ON_ONCE(device->dma_device);
 	if (device->dev.dma_ops) {
 		/*
@@ -455,16 +454,25 @@ int ib_register_device(struct ib_device *device,
 		 * into device->dev.
 		 */
 		device->dma_device = &device->dev;
-		if (!device->dev.dma_mask)
-			device->dev.dma_mask = parent->dma_mask;
-		if (!device->dev.coherent_dma_mask)
-			device->dev.coherent_dma_mask =
-				parent->coherent_dma_mask;
+		if (!device->dev.dma_mask) {
+			if (parent)
+				device->dev.dma_mask = parent->dma_mask;
+			else
+				WARN_ON_ONCE(true);
+		}
+		if (!device->dev.coherent_dma_mask) {
+			if (parent)
+				device->dev.coherent_dma_mask =
+					parent->coherent_dma_mask;
+			else
+				WARN_ON_ONCE(true);
+		}
 	} else {
 		/*
 		 * The caller did not provide custom DMA operations. Use the
 		 * DMA mapping operations of the parent device.
 		 */
+		WARN_ON_ONCE(!parent);
 		device->dma_device = parent;
 	}
 

drivers/infiniband/core/sysfs.c

@@ -1276,7 +1276,6 @@ int ib_device_register_sysfs(struct ib_device *device,
 	int ret;
 	int i;
 
-	WARN_ON_ONCE(!device->dev.parent);
 	ret = dev_set_name(class_dev, "%s", device->name);
 	if (ret)
 		return ret;