Cc Tianshu and others. Hi, Dan, Thanks a lot for the code review. > -----Original Message----- > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx] > Sent: Friday, January 4, 2019 6:29 AM > To: Zhi, Yong <yong.zhi@xxxxxxxxx> > Cc: linux-media@xxxxxxxxxxxxxxx > Subject: [bug report] media: staging/intel-ipu3: Add imgu top level pci device > driver > > Hello Yong Zhi, > > The patch 7fc7af649ca7: "media: staging/intel-ipu3: Add imgu top level pci > device driver" from Dec 6, 2018, leads to the following static checker warning: > > drivers/staging/media/ipu3/ipu3.c:493 imgu_isr_threaded() > warn: 'b' is an error pointer or valid > > drivers/staging/media/ipu3/ipu3.c > 472 static irqreturn_t imgu_isr_threaded(int irq, void *imgu_ptr) > 473 { > 474 struct imgu_device *imgu = imgu_ptr; > 475 struct imgu_media_pipe *imgu_pipe; > 476 int p; > 477 > 478 /* Dequeue / queue buffers */ > 479 do { > 480 u64 ns = ktime_get_ns(); > 481 struct ipu3_css_buffer *b; > 482 struct imgu_buffer *buf = NULL; > 483 unsigned int node, pipe; > 484 bool dummy; > 485 > 486 do { > 487 mutex_lock(&imgu->lock); > 488 b = ipu3_css_buf_dequeue(&imgu->css); > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > ipu3_css_buf_dequeue() doesn't return NULL. > > 489 mutex_unlock(&imgu->lock); > 490 } while (PTR_ERR(b) == -EAGAIN); > 491 > 492 if (IS_ERR_OR_NULL(b)) { > ^^^^^^^^^^^^^^^^^ > --> 493 if (!b || PTR_ERR(b) == -EBUSY) /* All done */ > ^^ > When a function returns both NULL and error pointers, then NULL is > considered a special case of success. Like perhaps you request a feature, but > that feature isn't enabled in the config. It's fine, because the user *chose* to > turn off the feature, so it's not an error but we also don't have a valid pointer > we can use. > > It looks like you were probably trying to do something like that but you > missed part of the commit? Otherwise we should delete the dead code. > Ack, with recent code changes the NULL check becomes useless, thanks for catching this. > 494 break; > 495 dev_err(&imgu->pci_dev->dev, > 496 "failed to dequeue buffers (%ld)\n", > 497 PTR_ERR(b)); > 498 break; > 499 } > 500 > > regards, > dan carpenter
