Re: [PATCH 2/5] io_uring: bpf: add io_uring_ctx setup for BPF into one list

[Caleb Sander Mateos <csander@purestorage.com>]

On Tue, Nov 4, 2025 at 8:22 AM Ming Lei <ming.lei@redhat.com> wrote:
>
> Add io_uring_ctx setup for BPF into one list, and prepare for syncing
> bpf struct_ops register and un-register.
>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  include/linux/io_uring_types.h |  5 +++++
>  include/uapi/linux/io_uring.h  |  5 +++++
>  io_uring/bpf.c                 | 15 +++++++++++++++
>  io_uring/io_uring.c            |  7 +++++++
>  io_uring/io_uring.h            |  3 ++-
>  io_uring/uring_bpf.h           | 11 +++++++++++
>  6 files changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
> index 92780764d5fa..d2e098c3fd2c 100644
> --- a/include/linux/io_uring_types.h
> +++ b/include/linux/io_uring_types.h
> @@ -465,6 +465,11 @@ struct io_ring_ctx {
>         struct io_mapped_region         ring_region;
>         /* used for optimised request parameter and wait argument passing  */
>         struct io_mapped_region         param_region;
> +
> +#ifdef CONFIG_IO_URING_BPF
> +       /* added to uring_bpf_ctx_list */
> +       struct list_head                bpf_node;
> +#endif
>  };
>
>  /*
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index b167c1d4ce6e..b8c49813b4e5 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -237,6 +237,11 @@ enum io_uring_sqe_flags_bit {
>   */
>  #define IORING_SETUP_SQE_MIXED         (1U << 19)
>
> +/*
> + * Allow to submit bpf IO
> + */
> +#define IORING_SETUP_BPF               (1U << 20)

Is the setup flag really necessary? It doesn't look like there's much
overhead to allowing BPF programs to be used on any io_ring_ctx, so I
would be inclined to avoid needing to set an additional flag to use
it.

Best,
Caleb


> +
>  enum io_uring_op {
>         IORING_OP_NOP,
>         IORING_OP_READV,
> diff --git a/io_uring/bpf.c b/io_uring/bpf.c
> index 8c47df13c7b5..bb1e37d1e804 100644
> --- a/io_uring/bpf.c
> +++ b/io_uring/bpf.c
> @@ -7,6 +7,9 @@
>  #include "io_uring.h"
>  #include "uring_bpf.h"
>
> +static DEFINE_MUTEX(uring_bpf_ctx_lock);
> +static LIST_HEAD(uring_bpf_ctx_list);
> +
>  int io_uring_bpf_issue(struct io_kiocb *req, unsigned int issue_flags)
>  {
>         return -ECANCELED;
> @@ -24,3 +27,15 @@ void io_uring_bpf_fail(struct io_kiocb *req)
>  void io_uring_bpf_cleanup(struct io_kiocb *req)
>  {
>  }
> +
> +void uring_bpf_add_ctx(struct io_ring_ctx *ctx)
> +{
> +       guard(mutex)(&uring_bpf_ctx_lock);
> +       list_add(&ctx->bpf_node, &uring_bpf_ctx_list);
> +}
> +
> +void uring_bpf_del_ctx(struct io_ring_ctx *ctx)
> +{
> +       guard(mutex)(&uring_bpf_ctx_lock);
> +       list_del(&ctx->bpf_node);
> +}
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index 3f0489261d11..38f03f6c28cb 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -105,6 +105,7 @@
>  #include "rw.h"
>  #include "alloc_cache.h"
>  #include "eventfd.h"
> +#include "uring_bpf.h"
>
>  #define SQE_COMMON_FLAGS (IOSQE_FIXED_FILE | IOSQE_IO_LINK | \
>                           IOSQE_IO_HARDLINK | IOSQE_ASYNC)
> @@ -352,6 +353,9 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
>         io_napi_init(ctx);
>         mutex_init(&ctx->mmap_lock);
>
> +       if (ctx->flags & IORING_SETUP_BPF)
> +               uring_bpf_add_ctx(ctx);
> +
>         return ctx;
>
>  free_ref:
> @@ -2855,6 +2859,9 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
>         if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
>                 static_branch_dec(&io_key_has_sqarray);
>
> +       if (ctx->flags & IORING_SETUP_BPF)
> +               uring_bpf_del_ctx(ctx);
> +
>         percpu_ref_exit(&ctx->refs);
>         free_uid(ctx->user);
>         io_req_caches_free(ctx);
> diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
> index 23c268ab1c8f..4baf21a9e1ee 100644
> --- a/io_uring/io_uring.h
> +++ b/io_uring/io_uring.h
> @@ -55,7 +55,8 @@
>                         IORING_SETUP_NO_SQARRAY |\
>                         IORING_SETUP_HYBRID_IOPOLL |\
>                         IORING_SETUP_CQE_MIXED |\
> -                       IORING_SETUP_SQE_MIXED)
> +                       IORING_SETUP_SQE_MIXED |\
> +                       IORING_SETUP_BPF)
>
>  #define IORING_ENTER_FLAGS (IORING_ENTER_GETEVENTS |\
>                         IORING_ENTER_SQ_WAKEUP |\
> diff --git a/io_uring/uring_bpf.h b/io_uring/uring_bpf.h
> index bde774ce6ac0..b6cda6df99b1 100644
> --- a/io_uring/uring_bpf.h
> +++ b/io_uring/uring_bpf.h
> @@ -7,6 +7,10 @@ int io_uring_bpf_issue(struct io_kiocb *req, unsigned int issue_flags);
>  int io_uring_bpf_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
>  void io_uring_bpf_fail(struct io_kiocb *req);
>  void io_uring_bpf_cleanup(struct io_kiocb *req);
> +
> +void uring_bpf_add_ctx(struct io_ring_ctx *ctx);
> +void uring_bpf_del_ctx(struct io_ring_ctx *ctx);
> +
>  #else
>  static inline int io_uring_bpf_issue(struct io_kiocb *req, unsigned int issue_flags)
>  {
> @@ -22,5 +26,12 @@ static inline void io_uring_bpf_fail(struct io_kiocb *req)
>  static inline void io_uring_bpf_cleanup(struct io_kiocb *req)
>  {
>  }
> +
> +static inline void uring_bpf_add_ctx(struct io_ring_ctx *ctx)
> +{
> +}
> +static inline void uring_bpf_del_ctx(struct io_ring_ctx *ctx)
> +{
> +}
>  #endif
>  #endif
> --
> 2.47.0
>