Re: [PATCH 1/2] io_uring: switch struct io_ring_ctx internal bitfields to flags

[Gabriel Krisman Bertazi <krisman@suse.de>]

Jens Axboe <axboe@kernel.dk> writes:

> Bitfields cannot be set and checked atomically, and this makes it more
> clear that these are indeed in shared storage and must be checked and
> set in a sane fashion. This is in preparation for annotating a few of
> the known racy, but harmless, flags checking.
>
> No intended functional changes in this patch.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  include/linux/io_uring_types.h | 32 +++++++------
>  io_uring/eventfd.c             |  4 +-
>  io_uring/io_uring.c            | 82 +++++++++++++++++-----------------
>  io_uring/io_uring.h            |  9 ++--
>  io_uring/msg_ring.c            |  2 +-
>  io_uring/register.c            |  8 ++--
>  io_uring/rsrc.c                |  8 ++--
>  io_uring/tctx.c                |  2 +-
>  io_uring/timeout.c             |  4 +-
>  io_uring/tw.c                  |  2 +-
>  10 files changed, 80 insertions(+), 73 deletions(-)
>
> diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
> index dd1420bfcb73..b84576374c7b 100644
> --- a/include/linux/io_uring_types.h
> +++ b/include/linux/io_uring_types.h
> @@ -268,24 +268,28 @@ struct io_alloc_cache {
>  	unsigned int		init_clear;
>  };
>  
> +enum {
> +	IO_RING_F_DRAIN_NEXT		= BIT(0),
> +	IO_RING_F_OP_RESTRICTED		= BIT(1),
> +	IO_RING_F_REG_RESTRICTED	= BIT(2),
> +	IO_RING_F_OFF_TIMEOUT_USED	= BIT(3),
> +	IO_RING_F_DRAIN_ACTIVE		= BIT(4),
> +	IO_RING_F_HAS_EVFD		= BIT(5),
> +	/* all CQEs should be posted only by the submitter task */
> +	IO_RING_F_TASK_COMPLETE		= BIT(6),
> +	IO_RING_F_LOCKLESS_CQ		= BIT(7),
> +	IO_RING_F_SYSCALL_IOPOLL	= BIT(8),
> +	IO_RING_F_POLL_ACTIVATED	= BIT(9),
> +	IO_RING_F_DRAIN_DISABLED	= BIT(10),
> +	IO_RING_F_COMPAT		= BIT(11),
> +	IO_RING_F_IOWQ_LIMITS_SET	= BIT(12),
> +};
> +
>  struct io_ring_ctx {
>  	/* const or read-mostly hot data */
>  	struct {
>  		unsigned int		flags;
> -		unsigned int		drain_next: 1;
> -		unsigned int		op_restricted: 1;
> -		unsigned int		reg_restricted: 1;
> -		unsigned int		off_timeout_used: 1;
> -		unsigned int		drain_active: 1;
> -		unsigned int		has_evfd: 1;
> -		/* all CQEs should be posted only by the submitter task */
> -		unsigned int		task_complete: 1;
> -		unsigned int		lockless_cq: 1;
> -		unsigned int		syscall_iopoll: 1;
> -		unsigned int		poll_activated: 1;
> -		unsigned int		drain_disabled: 1;
> -		unsigned int		compat: 1;
> -		unsigned int		iowq_limits_set : 1;
> +		unsigned int		int_flags;

Jens,

What does the int prefix means in this context?

-- 
Gabriel Krisman Bertazi