Re: [Valgrind-developers] More updates

[Julian S. <js...@ac...>]

Ok, it was just a sanity check.  I'm assuming you've got this
all figured out and will clean up and/or nuke get_current_tid_1_if_root
as you see fit.

J


On Tuesday 22 October 2002 8:35 am, Jeremy Fitzhardinge wrote:
> On Mon, 2002-10-21 at 21:45, Julian Seward wrote:
>     Nick: I spotted the infamous (?) VG_(get_current_tid_1_if_root)
>     and specifically this:
>
>        if (0 == vg_tid_currently_in_baseBlock)
>           return 1;     /* root thread */
>
>     What's the meaning of the 0 here?  Where is it set?  AFAICS the only
>     valid values of vg_tid_currently_in_baseBlock are either 1 ..
> VG_N_THREADS or VG_INVALID_THREADID, so I guess I'm missing something here?
>
> No, I don't think so.  I don't think that function means anything at
> all.  I was very close to removing it altogether.
>
>     I don't feel like I'm seeing a consistent story I'm happy with re
>     vg_tid_currently_in_baseBlock -- can you two clarify?
>
> I put the stronger assert into save_thread_state() because I couldn't
> see any good reason why the tid argument should ever mismatch the value
> of vg_tid_currently_in_baseBlock.  The assertion failed on the first
> thread create, but I think my fix makes sense.  Thread creation copies
> the parent thread's context into the child via the baseBlock.  In a
> sense the ownership of the baseBlock changes during the copy, which is
> what the assignment to vg_tid_currently_in_baseBlock indicates:
>
>     VG_(load_thread_state)(parent_tid);		/* load parent thread state into
> baseBlock */ +   vg_tid_currently_in_baseBlock = tid;	/* give ownership of
> baseBlock to child */ VG_(save_thread_state)(tid);		/* save new state into
> new thread */
>
>
>     It seems like, with that change, it will be impossible to
>     know from the value of vg_tid_currently_in_baseBlock whether or
>     not baseBlock is "full".
>
> No, because save_thread_state() assigns vg_tid_currently_in_baseBlock
> withVG_INVALID_THREADID, so you know the baseBlock contains nothing
> afterwards.  It gets reassigned with a valid tid on load_thread_state().
>
>     J