Awaiting Read and Write Half concurrently causes spin lock.

[Frostie314159]

Version

│       └── tokio-io v0.1.13
│   └── tokio v1.36.0
│       └── tokio-macros v2.2.0 (proc-macro)
│   └── tokio v1.36.0 (*)
└── tokio v1.36.0 (*)
└── tokio v1.36.0 (*)

Platform
Linux simon-framework 6.1.80-1-MANJARO #1 SMP PREEMPT_DYNAMIC Fri Mar 1 18:09:53 UTC 2024 x86_64 GNU/Linux

Description
When using the split function and awaiting both the read and write half concurrently, a spin lock is triggered, which causes cpu usage to skyrocket. This is actually noted in the code at tokio/io/split.rs.

[Darksonn]

Thank you for the issue. We should probably fix the spinlock, I agree.