On Friday 15 August 2008 18:37:31, Daniel Jacobowitz wrote:
> On Fri, Aug 08, 2008 at 02:37:57AM +0100, Pedro Alves wrote:
> > This patch adjusts the procfs target, so that it registers the main
> > thread in GDB's thread table.
>
> This looks OK to me (took me a couple of tries to convince myself it
> was right, but I'm convinced now).

I'm sorry to had convinced you wrong.  :-(

I noticed that before, when we went multi-threaded, we would keep
the main process listed with proc->tid == 0, and we would just
create a new procinfo for the main lwp, which is a little
redundant, but indeed simplifies things.

procfs_wait:
		  /* In addition, it's possible that this is the first
		   * new thread we've seen, in which case we may not
		   * have created entries for inferior_ptid yet.
		   */
		  if (TIDGET (inferior_ptid) != 0)
		    {
		      if (!in_thread_list (inferior_ptid))
			add_thread (inferior_ptid);
		      if (find_procinfo (PIDGET (inferior_ptid),
					 TIDGET (inferior_ptid)) == NULL)
			create_procinfo (PIDGET (inferior_ptid),
					 TIDGET (inferior_ptid));
		    }

If I instead do that right on target_create_inferior and target_attach,
we're done -- there's always a thread, and there's always a procinfo for
it too.

You asked me on IRC if the main lwp is also available in
the /proc tree, and although I somehow missed it, indeed it is there.

Here, 5642 is a single-threaded app:

 pedro@opensolaris:~/orlando/gdb/baseline/build-solaris/gdb$ ls /proc/5642/lwp/
 1

Here, 5613 is a multi-threaded app:

 pedro@opensolaris:~/orlando/gdb/baseline/build-solaris/gdb$ ls /proc/5613/lwp/
 1  2  3

We still have to use the main process procinfo entry, to get at
/proc/<pid>/map /proc/<pid>/as, because as expected, those are
not found under the lwp/1 directory:

 pedro@opensolaris:~/orlando/gdb/baseline/build-solaris/gdb$  ls /proc/5613/lwp/1/
 lwpctl  lwpsinfo  lwpstatus  lwpusage  templates  xregs

My previous path had broken creating core dumps in multi-threaded apps,
as iterating over thread procinfo's would miss the main process.

Please find attached a new patch.  This one's much simpler.

Only procfs.c changed.

-- 
Pedro Alves