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Date: Fri, 21 May 2021 01:42:57 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: io-uring@...r.kernel.org, netdev@...r.kernel.org,
bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Jens Axboe <axboe@...nel.dk>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Horst Schirmeier <horst.schirmeier@...dortmund.de>,
"Franz-B . Tuneke" <franz-bernhard.tuneke@...dortmund.de>,
Christian Dietrich <stettberger@...ucode.de>
Subject: Re: [PATCH 14/23] io_uring: add support for bpf requests
On 5/19/21 3:13 PM, Pavel Begunkov wrote:
> Wire up a new io_uring operation type IORING_OP_BPF, which executes a
> specified BPF program from the registered prog table. It doesn't allow
> to do anything useful for now, no BPF functions are allowed apart from
> basic ones.
>
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
> ---
> fs/io_uring.c | 92 +++++++++++++++++++++++++++++++++++
> include/uapi/linux/io_uring.h | 1 +
> 2 files changed, 93 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index b13cbcd5c47b..20fddc5945f2 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -682,6 +682,11 @@ struct io_unlink {
> struct filename *filename;
> };
>
> +struct io_bpf {
> + struct file *file;
> + struct bpf_prog *prog;
> +};
> +
> struct io_completion {
> struct file *file;
> struct list_head list;
> @@ -826,6 +831,7 @@ struct io_kiocb {
> struct io_shutdown shutdown;
> struct io_rename rename;
> struct io_unlink unlink;
> + struct io_bpf bpf;
> /* use only after cleaning per-op data, see io_clean_op() */
> struct io_completion compl;
> };
> @@ -875,6 +881,9 @@ struct io_defer_entry {
> u32 seq;
> };
>
> +struct io_bpf_ctx {
> +};
> +
> struct io_op_def {
> /* needs req->file assigned */
> unsigned needs_file : 1;
> @@ -1039,6 +1048,7 @@ static const struct io_op_def io_op_defs[] = {
> },
> [IORING_OP_RENAMEAT] = {},
> [IORING_OP_UNLINKAT] = {},
> + [IORING_OP_BPF] = {},
> };
>
> static bool io_disarm_next(struct io_kiocb *req);
> @@ -1070,6 +1080,7 @@ static void io_rsrc_put_work(struct work_struct *work);
> static void io_req_task_queue(struct io_kiocb *req);
> static void io_submit_flush_completions(struct io_comp_state *cs,
> struct io_ring_ctx *ctx);
> +static void io_bpf_run(struct io_kiocb *req, unsigned int issue_flags);
> static bool io_poll_remove_waitqs(struct io_kiocb *req);
> static int io_req_prep_async(struct io_kiocb *req);
>
> @@ -3931,6 +3942,53 @@ static int io_openat(struct io_kiocb *req, unsigned int issue_flags)
> return io_openat2(req, issue_flags);
> }
>
> +static int io_bpf_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> +{
> + struct io_ring_ctx *ctx = req->ctx;
> + struct bpf_prog *prog;
> + unsigned int idx;
> +
> + if (unlikely(ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
> + return -EINVAL;
> + if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
> + return -EINVAL;
> + if (sqe->ioprio || sqe->len || sqe->cancel_flags)
> + return -EINVAL;
> + if (sqe->addr)
> + return -EINVAL;
> +
> + idx = READ_ONCE(sqe->off);
> + if (unlikely(idx >= ctx->nr_bpf_progs))
> + return -EFAULT;
> + idx = array_index_nospec(idx, ctx->nr_bpf_progs);
> + prog = ctx->bpf_progs[idx].prog;
> + if (!prog)
> + return -EFAULT;
> +
> + req->bpf.prog = prog;
> + return 0;
> +}
> +
> +static void io_bpf_run_task_work(struct callback_head *cb)
> +{
> + struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work);
> + struct io_ring_ctx *ctx = req->ctx;
> +
> + mutex_lock(&ctx->uring_lock);
> + io_bpf_run(req, 0);
> + mutex_unlock(&ctx->uring_lock);
> +}
> +
> +static int io_bpf(struct io_kiocb *req, unsigned int issue_flags)
> +{
> + init_task_work(&req->task_work, io_bpf_run_task_work);
> + if (unlikely(io_req_task_work_add(req))) {
> + req_ref_get(req);
> + io_req_task_queue_fail(req, -ECANCELED);
> + }
> + return 0;
> +}
> +
> static int io_remove_buffers_prep(struct io_kiocb *req,
> const struct io_uring_sqe *sqe)
> {
> @@ -6002,6 +6060,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> return io_renameat_prep(req, sqe);
> case IORING_OP_UNLINKAT:
> return io_unlinkat_prep(req, sqe);
> + case IORING_OP_BPF:
> + return io_bpf_prep(req, sqe);
> }
>
> printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
> @@ -6269,6 +6329,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
> case IORING_OP_UNLINKAT:
> ret = io_unlinkat(req, issue_flags);
> break;
> + case IORING_OP_BPF:
> + ret = io_bpf(req, issue_flags);
> + break;
> default:
> ret = -EINVAL;
> break;
> @@ -10303,6 +10366,35 @@ const struct bpf_verifier_ops bpf_io_uring_verifier_ops = {
> .is_valid_access = io_bpf_is_valid_access,
> };
>
> +static void io_bpf_run(struct io_kiocb *req, unsigned int issue_flags)
> +{
> + struct io_ring_ctx *ctx = req->ctx;
> + struct io_bpf_ctx bpf_ctx;
> + struct bpf_prog *prog;
> + int ret = -EAGAIN;
> +
> + lockdep_assert_held(&req->ctx->uring_lock);
> +
> + if (unlikely(percpu_ref_is_dying(&ctx->refs) ||
> + atomic_read(&req->task->io_uring->in_idle)))
> + goto done;
> +
> + memset(&bpf_ctx, 0, sizeof(bpf_ctx));
> + prog = req->bpf.prog;
> +
> + if (prog->aux->sleepable) {
Looks forgot to amend, the condition should be inversed.
> + rcu_read_lock();
> + bpf_prog_run_pin_on_cpu(req->bpf.prog, &bpf_ctx);
> + rcu_read_unlock();
> + } else {
> + bpf_prog_run_pin_on_cpu(req->bpf.prog, &bpf_ctx);
> + }
> +
> + ret = 0;
> +done:
> + __io_req_complete(req, issue_flags, ret, 0);
> +}
> +
> SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
> void __user *, arg, unsigned int, nr_args)
> {
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index b450f41d7389..25ab804670e1 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -138,6 +138,7 @@ enum {
> IORING_OP_SHUTDOWN,
> IORING_OP_RENAMEAT,
> IORING_OP_UNLINKAT,
> + IORING_OP_BPF,
>
> /* this goes last, obviously */
> IORING_OP_LAST,
>
--
Pavel Begunkov
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