Re: [Devel] [PATCH hci-8.1] fs/fuse kio: start connect once per rpc_queue_work batch

[Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>]

On 9/22/26 17:01, Alexey Kuznetsov wrote:
> Hello!
> 
> On Tue, Sep 22, 2026 at 10:11 PM Vladimir Riabchun
> <vladimir.riabchun@virtuozzo.com> wrote:
>> Condition in BUG_ON(msg->rpc != (requeue ? ep: NULL)) was too hard
>> for me to process correctly in my head, while writing reply I decoded
>> it.
> 
> Exactly. As I said the code is too scary.
> 
>> What's wrong with tail calls? If it is inlined, we will just patch
>> the parent and stack checks would be performed for parent.
> 
> tail called functions are not on stack. at least they used to,
> probably with ORCA they are visible, I still did not learn this.
> 
> Return should not be an issue, old code remains executable and not corrupted,
> it can live forever if someobe sleeps in it.
> Or it does not?? I thought it uses __fentry__ placeholder to redirect.

I mentioned return sites to show that these stack trace checks might be
useful even if patching does stop_machine. But it is not the case for
ftrace-based livepatches.

There I think guys just want some additional guarantees on executed code
state, to think less about such problems.

-- 
Best regards, Riabchun Vladimir
Linux Kernel Developer, Virtuozzo

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