ipu6-isys: Fix crash when ipu_isys_csi2_init() fails

Calling isys_unregister_subdevices() on errors in
isys_register_subdevices() leads to not yet registered subdevs
getting unregistered resulting in a NULL pointer deref:

[  143.100638] BUG: kernel NULL pointer dereference, address: 0000000000000000
...
[  143.100655] RIP: 0010:__wake_up_common+0x2a/0xa0
...
[  143.100672] Call Trace:
[  143.100674]  <TASK>
[  143.100676]  ? __die+0x23/0x70
[  143.100680]  ? page_fault_oops+0x171/0x4e0
[  143.100684]  ? exc_page_fault+0x7f/0x180
[  143.100687]  ? asm_exc_page_fault+0x26/0x30
[  143.100690]  ? __wake_up_common+0x2a/0xa0
[  143.100692]  __wake_up+0x36/0x60
[  143.100697]  __vb2_queue_cancel+0xd2/0x290 [videobuf2_common]
[  143.100706]  vb2_core_queue_release+0x22/0x50 [videobuf2_common]
[  143.100714]  isys_unregister_subdevices+0x49/0xb0 [intel_ipu6_isys]
[  143.100723]  isys_probe+0x59c/0xa30 [intel_ipu6_isys]

Fix this by only cleaning up subdevs which have actually been registered.

Signed-off-by: Hans de Goede <[email protected]>

drivers/media/pci/intel/ipu-isys.c

@@ -382,15 +382,12 @@ static int isys_register_subdevices(struct ipu_isys *isys)
 	const struct ipu_isys_internal_csi2_pdata *csi2 =
 	    &isys->pdata->ipdata->csi2;
 	struct ipu_isys_csi2_be_soc *csi2_be_soc;
-	unsigned int i, k;
-	int rval;
+	int i = 0, k = 0, rval;
 
 	isys->csi2 = devm_kcalloc(&isys->adev->dev, csi2->nports,
 				  sizeof(*isys->csi2), GFP_KERNEL);
-	if (!isys->csi2) {
-		rval = -ENOMEM;
-		goto fail;
-	}
+	if (!isys->csi2)
+		return -ENOMEM;
 
 	for (i = 0; i < csi2->nports; i++) {
 		rval = ipu_isys_csi2_init(&isys->csi2[i], isys,
@@ -425,15 +422,25 @@ static int isys_register_subdevices(struct ipu_isys *isys)
 			if (rval) {
 				dev_info(&isys->adev->dev,
 					 "can't create link csi2->be_soc\n");
-				goto fail;
+				isys_unregister_subdevices(isys);
+				return rval;
 			}
 		}
 	}
 
 	return 0;
 
 fail:
-	isys_unregister_subdevices(isys);
+	while (--k >= 0) {
+		dev_info(&isys->adev->dev, "foo %d\n", k);
+		ipu_isys_csi2_be_soc_cleanup(&isys->csi2_be_soc[k]);
+	}
+
+	while (--i >= 0) {
+		dev_info(&isys->adev->dev, "bar %d\n", k);
+		ipu_isys_csi2_cleanup(&isys->csi2[i]);
+	}
+
 	return rval;
 }