Re: [PATCH] gdb: iterate over targets, not inferiors, to commit resumed

[Simon Marchi <simark@simark.ca>]

On 3/1/24 10:52, Tankut Baris Aktemur wrote:
> When committing resumed threads of targets, iterate over targets, not
> inferiors, so that we don't call commit_resumed multiple times for
> targets that have multiple inferiors.  This gives more concise code.
> 
> Similarly, iterate over targets when setting the commit_resumed_state
> of targets.
> 
> No behavioral change is expected or intended with this patch.

Hi Baris,

The change in maybe_call_commit_resumed_all_targets might not play well
with the amd-dbgapi target (and is probably the reason this code was
written like this in the first place).  Right now, it's kind of a hack,
but the amd-dbgapi target sits on top of the linux-nat target, in the
arch stratum layer.  It intercepts some target calls, and really acts as
a second process target for the inferior, without being an actual
process_stratum_target.

Imagine you have two inferiors, one debugging a plain Linux program and
the other a program using the GPU.  The target stacks will look like:

                  inf1       inf2
    arch stratum: <empty>    amd-dbgapi
 process stratum: linux-nat  linux-nat

By iterating only on process stratum targets, commit_resumed will only
be called on inferior 1, and therefore the amd-dbgapi target will never
see it.  The GPU threads will not effectively be resumed.

Our plan is to try to make amd-dbgapi a proper process_stratum_target
and allow inferiors to have more than one process target, in which case
your change would probably be fine.  We haven't started on that front
yet, unfortunately.

The change in maybe_set_commit_resumed_all_targets is probably fine
though.

Simon