Re: [PATCH v2 02/25] ALSA: pcm: Add copy ops with iov_iter

On Tue, Aug 15, 2023 at 09:01:13PM +0200, Takashi Iwai wrote:

• if (copy_from_user(get_dma_ptr(substream->runtime, channel, hwoff),

• 	   (void __user *)buf, bytes))
  

• if (!copy_from_iter(get_dma_ptr(substream->runtime, channel, hwoff),

• 	    bytes, iter))
  

The former is "if not everything got copied", the latter - "if nothing got copied"; the same goes for other places like that.