Re: [commit/windows] Add thread ID in SuspendThread error warning message.

[Joel Brobecker <brobecker@adacore.com>]

> >That's interesting. I have the following patch in AdaCore's tree
> >which I have been uhming and ahming about. Would it apply to your
> >situation as well?
> >
> >-                   warning (_("SuspendThread failed. (winerr %u)"),
> >-                            (unsigned) err);
> >-                   return NULL;
> >+                   /* If SuspendThread failed with error 5 (access
> >+                      denied), then ignore the error.  It's unclear
> >+                      where this comes from and how to prevent it.
> >+                      But in the meantime, ignoring it seems to allow
> >+                      us to inspect the thread (including fetching
> >+                      registers) without apparent ill effect.  */
> >+                   if (err != 5)
> >+                     {
> >+                       warning (_("SuspendThread (tid=0x%x) failed."
> >+                                  " (winerr %d)"),
> >+                                (unsigned) id, (unsigned) err);
> >+                       return NULL;
> >+                     }
> 
> That's basically what I'm doing in the Cygwin release:
> 
>                 if (SuspendThread (th->h) == (DWORD) -1)
>                   {
>                     DWORD err = GetLastError ();
> -                   warning (_("SuspendThread failed. (winerr %u)"),
> -                            (unsigned) err);
> +                   /* Can get a ERROR_INVALID_HANDLE if the main thread has
> +                      exited. */
> +                   if (err != ERROR_INVALID_HANDLE)
> +                     warning (_("SuspendThread(%p) failed. (winerr %u)"),
> +                              (void *) th->h, (unsigned) err);
>                     return NULL;
>                   }
>                 th->suspended = 1;

That's interesting again. If I read MSDN right, ERROR_INVALID_HANDLE
is 6, whereas I ignore the error for code 5 (access denied). I say
that it's interesting, because the report we had was for the error
you ignore.

Someone was able to reproduce this issue consistently, and I wish
they had more time to help me investigate this. If we had more
details on the two error cases, I would not mind checking in
a merge of both our changes.

-- 
Joel