On Thu, Apr 22, 2021 at 12:11:44PM +0300, Dan Carpenter wrote: > The intent here was to return negative error codes but it actually > returns positive values. The problem is that type promotion with > ternary operations is quite complicated. > > "ret" is an int. "copied" is a u32. And the snoop_file_read() function > returns long. What happens is that "ret" is cast to u32 and becomes > positive then it's cast to long and it's still positive. > > Fix this by removing the ternary so that "ret" is type promoted directly > to long. Hmm... Let's grep for kfifo_to_user() - smells like a possible recurring bug... Yup - samples/kfifo/bytestream-example.c:138: ret = kfifo_to_user(&test, buf, count, &copied); samples/kfifo/inttype-example.c:131: ret = kfifo_to_user(&test, buf, count, &copied); samples/kfifo/record-example.c:145: ret = kfifo_to_user(&test, buf, count, &copied); All three are exactly like that one.
