On Fri, Jul 03, 2020 at 02:16:04AM +0800, kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > head: d37d57041350dff35dd17cbdf9aef4011acada38 > commit: 261463dbc34ff0acafe4d84df04535b48a15afea [2656/5054] media: rc: add support for Infrared Toy and IR Droid devices > compiler: gcc-9 (Debian 9.3.0-14) 9.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > cppcheck warnings: (new ones prefixed by >>) > > >> drivers/media/rc/ir_toy.c:410:6: warning: Variable 'err' is reassigned a value before the old one has been used. [redundantAssignment] > err = usb_submit_urb(irtoy->urb_in, GFP_KERNEL); > ^ > drivers/media/rc/ir_toy.c:352:0: note: Variable 'err' is reassigned a value before the old one has been used. > int i, pipe, err = -ENOMEM; > ^ > drivers/media/rc/ir_toy.c:410:6: note: Variable 'err' is reassigned a value before the old one has been used. > err = usb_submit_urb(irtoy->urb_in, GFP_KERNEL); > ^ > I think gcc is confused here. err does get used in an error path. On code path line 377, goto free_irtoy; err is returned from the function. Interestingly if you remove the err initializer (' = -ENOMEM') then gcc does not warn about uninitialized data being returned (gcc 10.1.1 on Fedora 32). clang on the other does the right thing. No warnings on the original code, and if you remove the err initializer then you get: drivers/media/rc/ir_toy.c:474:9: note: uninitialized use occurs here return err; ^~~ Sean > vim +/err +410 drivers/media/rc/ir_toy.c > > 340 > 341 static int irtoy_probe(struct usb_interface *intf, > 342 const struct usb_device_id *id) > 343 { > 344 struct usb_host_interface *idesc = intf->cur_altsetting; > 345 struct usb_device *usbdev = interface_to_usbdev(intf); > 346 struct usb_endpoint_descriptor *ep_in = NULL; > 347 struct usb_endpoint_descriptor *ep_out = NULL; > 348 struct usb_endpoint_descriptor *ep = NULL; > 349 struct irtoy *irtoy; > 350 struct rc_dev *rc; > 351 struct urb *urb; > 352 int i, pipe, err = -ENOMEM; > 353 > 354 for (i = 0; i < idesc->desc.bNumEndpoints; i++) { > 355 ep = &idesc->endpoint[i].desc; > 356 > 357 if (!ep_in && usb_endpoint_is_bulk_in(ep) && > 358 usb_endpoint_maxp(ep) == MAX_PACKET) > 359 ep_in = ep; > 360 > 361 if (!ep_out && usb_endpoint_is_bulk_out(ep) && > 362 usb_endpoint_maxp(ep) == MAX_PACKET) > 363 ep_out = ep; > 364 } > 365 > 366 if (!ep_in || !ep_out) { > 367 dev_err(&intf->dev, "required endpoints not found\n"); > 368 return -ENODEV; > 369 } > 370 > 371 irtoy = kzalloc(sizeof(*irtoy), GFP_KERNEL); > 372 if (!irtoy) > 373 return -ENOMEM; > 374 > 375 irtoy->in = kmalloc(MAX_PACKET, GFP_KERNEL); > 376 if (!irtoy->in) > 377 goto free_irtoy; > 378 > 379 irtoy->out = kmalloc(MAX_PACKET, GFP_KERNEL); > 380 if (!irtoy->out) > 381 goto free_irtoy; > 382 > 383 rc = rc_allocate_device(RC_DRIVER_IR_RAW); > 384 if (!rc) > 385 goto free_irtoy; > 386 > 387 urb = usb_alloc_urb(0, GFP_KERNEL); > 388 if (!urb) > 389 goto free_rcdev; > 390 > 391 pipe = usb_rcvbulkpipe(usbdev, ep_in->bEndpointAddress); > 392 usb_fill_bulk_urb(urb, usbdev, pipe, irtoy->in, MAX_PACKET, > 393 irtoy_in_callback, irtoy); > 394 irtoy->urb_in = urb; > 395 > 396 urb = usb_alloc_urb(0, GFP_KERNEL); > 397 if (!urb) > 398 goto free_rcdev; > 399 > 400 pipe = usb_sndbulkpipe(usbdev, ep_out->bEndpointAddress); > 401 usb_fill_bulk_urb(urb, usbdev, pipe, irtoy->out, MAX_PACKET, > 402 irtoy_out_callback, irtoy); > 403 > 404 irtoy->dev = &intf->dev; > 405 irtoy->usbdev = usbdev; > 406 irtoy->rc = rc; > 407 irtoy->urb_out = urb; > 408 irtoy->pulse = true; > 409 > > 410 err = usb_submit_urb(irtoy->urb_in, GFP_KERNEL); > 411 if (err != 0) { > 412 dev_err(irtoy->dev, "fail to submit in urb: %d\n", err); > 413 return err; > 414 } > 415 > 416 err = irtoy_setup(irtoy); > 417 if (err) > 418 goto free_rcdev; > 419 > 420 dev_info(irtoy->dev, "version: hardware %u, firmware %u, protocol %u", > 421 irtoy->hw_version, irtoy->sw_version, irtoy->proto_version); > 422 > 423 if (irtoy->sw_version < MIN_FW_VERSION) { > 424 dev_err(irtoy->dev, "need firmware V%02u or higher", > 425 MIN_FW_VERSION); > 426 err = -ENODEV; > 427 goto free_rcdev; > 428 } > 429 > 430 usb_make_path(usbdev, irtoy->phys, sizeof(irtoy->phys)); > 431 > 432 rc->device_name = "Infrared Toy"; > 433 rc->driver_name = KBUILD_MODNAME; > 434 rc->input_phys = irtoy->phys; > 435 usb_to_input_id(usbdev, &rc->input_id); > 436 rc->dev.parent = &intf->dev; > 437 rc->priv = irtoy; > 438 rc->tx_ir = irtoy_tx; > 439 rc->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER; > 440 rc->map_name = RC_MAP_RC6_MCE; > 441 rc->rx_resolution = UNIT_NS; > 442 rc->timeout = IR_DEFAULT_TIMEOUT; > 443 > 444 /* > 445 * end of transmission is detected by absence of a usb packet > 446 * with more pulse/spaces. However, each usb packet sent can > 447 * contain 32 pulse/spaces, which can be quite lengthy, so there > 448 * can be a delay between usb packets. For example with nec there is a > 449 * 17ms gap between packets. > 450 * > 451 * So, make timeout a largish minimum which works with most protocols. > 452 */ > 453 rc->min_timeout = MS_TO_NS(40); > 454 rc->max_timeout = MAX_TIMEOUT_NS; > 455 > 456 err = rc_register_device(rc); > 457 if (err) > 458 goto free_rcdev; > 459 > 460 usb_set_intfdata(intf, irtoy); > 461 > 462 return 0; > 463 > 464 free_rcdev: > 465 usb_kill_urb(irtoy->urb_out); > 466 usb_free_urb(irtoy->urb_out); > 467 usb_kill_urb(irtoy->urb_in); > 468 usb_free_urb(irtoy->urb_in); > 469 rc_free_device(rc); > 470 free_irtoy: > 471 kfree(irtoy->in); > 472 kfree(irtoy->out); > 473 kfree(irtoy); > 474 return err; > 475 } > 476 > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
