io_uring_cqe_shift comment.

[YoSTEALTH]

Testing io_uring_cqe_shift, The comment says:

• for standard CQE its 1
• for big CQE its 2

I am actually getting 0 for standard cqe, and 1 when using IORING_SETUP_CQE32. Comment should be fixed? Maybe a test?

[alviroiskandar]

That's used for bit shift operation in io_uring_cqe_index().

#define io_uring_cqe_index(ring,ptr,mask) \
	(((ptr) & (mask)) << io_uring_cqe_shift(ring))

n << 0 is the same as n * 1
n << 1 is the same as n * 2

So basically, 0 means multiply by 1, and 1 means multiply by 2.

[YoSTEALTH]

@alviroiskandar Makes sense. So the comment the should be above io_uring_cqe_index

[isilence]

Yes, the comment should change. The entire 2nd line can be killed, these 1/2 description tries to verbatim repeat what the code does.