Re: [PATCH] Use "switch_to_thread" more thoroughly on gdbserver

[Pedro Alves <palves@redhat.com>]

On 09/15/2017 07:25 PM, Sergio Durigan Junior wrote:
> On Friday, September 15 2017, Pedro Alves wrote:
> 
>> Do you remember why that check is there in switch_to_thread in the
>> first place, as opposed to, say, an assertion?
> 
> I tried to do some archaeology here and find the patch that implemented
> this feature, and it seems to me that the patch always used 'if' instead
> of an 'assert'.  

Yeah, gdbserver's switch_to_thread was added with your fork
inferior sharing series.

> Maybe that's because GDB's version of switch_to_thread
> also doesn't assert that ptid != minus_one_ptid...

Except it does:

static void
switch_to_thread (thread_info *thr)
{
  gdb_assert (thr != NULL);
  ^^^^^^^^^^^^^^^^^^^^^^^^
...

Called from:

void
switch_to_thread (ptid_t ptid)
{
  if (ptid == null_ptid)
    switch_to_no_thread ();
  else
    switch_to_thread (find_thread_ptid (ptid));
}

... and find_thread_ptid returns NULL because there's
never a thread with ptid == minus_one_ptid.

Thanks,
Pedro Alves