Re: [PATCH 3/5] io_uring: bpf: extend io_uring with bpf struct_ops

[Ming Lei <ming.lei@redhat.com>]

On Wed, Nov 19, 2025 at 07:39:12AM -0700, Jonathan Corbet wrote:
> Ming Lei <ming.lei@redhat.com> writes:
> 
> > io_uring can be extended with bpf struct_ops in the following ways:
> 
> So I have a probably dumb question I ran into as I tried to figure this
> stuff out.  You define this maximum here...
> 
> > +#define MAX_BPF_OPS_COUNT	(1 << IORING_BPF_OP_BITS)
> 
> ...which sizes the bpf_ops array:
> 
> > +static struct uring_bpf_ops bpf_ops[MAX_BPF_OPS_COUNT];
> 
> Later, you do registration here:
> 
> > +static int io_bpf_reg_unreg(struct uring_bpf_ops *ops, bool reg)
> > +{
> > +	struct io_ring_ctx *ctx;
> > +	int ret = 0;
> > +
> > +	guard(mutex)(&uring_bpf_ctx_lock);
> > +	list_for_each_entry(ctx, &uring_bpf_ctx_list, bpf_node)
> > +		mutex_lock(&ctx->uring_lock);
> > +
> > +	if (reg) {
> > +		if (bpf_ops[ops->id].issue_fn)
> > +			ret = -EBUSY;
> > +		else
> > +			bpf_ops[ops->id] = *ops;
> > +	} else {
> > +		bpf_ops[ops->id] = (struct uring_bpf_ops) {0};
> > +	}
> > +
> > +	synchronize_srcu(&uring_bpf_srcu);
> > +
> > +	list_for_each_entry(ctx, &uring_bpf_ctx_list, bpf_node)
> > +		mutex_unlock(&ctx->uring_lock);
> > +
> > +	return ret;
> > +}
> 
> Nowhere do I find a test ensuring that ops->id is within range;
> MAX_BPF_OPS_COUNT never appears in a test.  What am I missing?

bits of `ops->id` is limited by IORING_BPF_OP_BITS and it is stored in top
8bits of ->bpf_flags, so ops->id is within the range naturally.


Thanks,
Ming