Re: [PATCH] gdb: use correct target in notify_thread_exited()

[Simon Marchi <simark@simark.ca>]

On 2026-05-05 03:56, Metzger, Markus T wrote:
>> This is unfortunately not correct, because target calls (annoyingly IMO)
>> use the target stack of the current inferior to find the target beneath.
>> If you are having to do this change, it means that this function is
>> called for a thread of inferior A, while inferior B is the current one.
>> What will happen is that you'll start with the top target of inferior A,
>> but if that target calls "target_ops::beneath()" to delegate to the
>> target beneath, that will jump to a target of inferior B.  If the
>> pid_to_str operation is handled by the top target of inferior A, it will
>> work, but not in the general case.
>>
>> As of today, the only fix for that would be to temporarily switch
>> inferior.
> 
> Those scoped_restore_foo are everywhere.  I tried to not rely on
> global state and instead use the arguments passed to the function,
> but I see now how this cannot work.  Makes you wonder why we
> even bother passing thread_info * and inferior *.

Indeed, if a random function takes an inferior parameter but also
requires that this inferior is the current one, it can be misleading.
It makes you think that it is global-context-agnostic, while it is not.
I try not to do this.

I would say that this "target calls rely on current inferior's target
stack" is the major blocker for continuing doing cleanups to pass
context through parameters, rather than global variables.

> I switch to the exited thread in v2.
> 
>> I once made a prototype [1] of passing down the target stack explicitly to
>> all target functions.  It would be quite invasive, but I don't see any
>> other solution if we want to lift that "target calls care about current
>> inferior" limitation.
>>
>> [1] https://review.lttng.org/c/binutils-gdb/+/5627
> 
> It's every call to inferior_thread() and current_inferior(), too.

I am not sure what you mean here, those are just simple getters.

Simon