Re: settrans

[Neal H Walfield]

On Wed, Jan 17, 2001 at 10:00:43PM -0500, Neal H Walfield wrote:
> On Wed, Jan 17, 2001 at 06:21:40PM -0500, Roland McGrath wrote:
> > I don't see anything obviously wrong (other than your spelling of 
> > "semantics").
> 
> Do you think it might be an error elsewhere, e.g. in gdb or the proc
> server?

Here is (hopefully) a clearer presentation of the problem.

After adding the aforementioned code to a clean tree, translators fail
to retreive their port to the proc server if one attaches to the
translator with gdb _during_ the pause.

Here are the different scenarios:

 * Just settrans it works fine:

        tty1 (0)$ settrans -acfg fs /hurd/ext2fs part/7
        tty1 (0)$ ls fs
        lost+found

 * The same goes if one attaches gdb later:

        tty1 (0)$ settrans -acfg fs /hurd/ext2fs part/7
        tty1 (0)$ ls fs
        lost+found

        tty2 (0)$ gdb /hurd/diskpart 808
        GNU gdb 5.0
        ...
        [Switching to thread 808.1]
        (gdb) c
        Continuing.

        tty1 (0)$ ls fs
        lost+found

 * If one pauses yet does not attach gdb, all still goes well:

        tty1 (0)$ settrans -acfgP fs /hurd/ext2fs part/7
        Translator pid: 845
        Pausing...
        tty1 (0)$ ls fs
        lost+found

 * Pausing and attaching gdb after hitting enter is also fine:

        tty2 (0)$ gdb /hurd/ext2fs 845
        GNU gdb 5.0
        ...
        (gdb) c
        Continuing.

        tty1 (0)$ ls fs
        lost+found

 * However, if fails when attaching during the pause:

        tty1 (0)$ settrans -acfgP fs /hurd/ext2fs part/7
        Translator pid: 851
        Pausing...

        tty2 (0)$ gdb /hurd/ext2fs 851
        GNU gdb 5.0
        ...
        (gdb)

        Now, hitting enter at the prompt followed by continuing in gdb:

        (gdb) c
        Continuing.
        from gdb:
        warning: Pid 851 died with unknown exit status, using SIGKILL.

        Program terminated with signal SIGKILL, Killed.
        The program no longer exists.

        And from termianl 1:

        tty1 (0)$ Translator startup failure: fsys_startup: (ipc/send)
        invalid destination port

 * It also dies if one connects gdb and continues before hitting enter;
   This has slightly different output:

        tty1 (0)$ settrans -acfgP fs /hurd/ext2fs part/7
        Translator pid: 876
        Pausing...


        tty2 (0)$ gdb /hurd/ext2fs 851
        GNU gdb 5.0
        ...
        (gdb) c
        Continuing.

        Back to terminal 1 and hit enter:

        ext2fs: ../../project/hurd/hurd-build/libdiskfs/init-startup.c:178:
        _diskfs_init_completed: Assertion `proc' failed.


Taking a look at init-startup.c shows the following:

        /* This is called when we have an ordinary environment, complete
           with proc and auth ports. */
        void
        _diskfs_init_completed ()
        {
          /* Some variables followed by the first lines of code: */

          /* Contact the startup server and register our shutdown request.
             If we get an error, print an informational message. */

          proc = getproc ();
          assert (proc);       <--  Line 178

        ...

Which was called by either diskfs_S_fsys_init (boot-start.c) or 
diskfs_startup_diskfs (init-startup.c).

Attaching to settrans during the pause shows that it is waiting for
a key:

        (gdb) up
        #8  0x8048ca9 in open_node (flags=0, underlying=0x11dfcd0, 
        underlying_type=0x11dfca8, task=62, cookie=0x0) at
        /include/stdio.h:545
        545       return __getc (stdin);

Breaking at the next line and hitting enter shows that everything
here is (relatively) sane:

        (gdb) n
        Cannot find bounds of current function
        (gdb) b 184
        Breakpoint 1 at 0x8048c85: file /include/stdio.h, line 184.
        (gdb) b settrans.c:184
        Breakpoint 2 at 0x8048cac: file
        ../../project/hurd/hurd-build/utils/settrans.c, line 184.
        (gdb) c
        Continuing.
        warning: Can't wait for pid 897: No child processes

        Breakpoint 2, open_node (flags=0, underlying=0x11dfcd0, 
        underlying_type=0x11dfca8, task=62, cookie=0x0)
            at ../../project/hurd/hurd-build/utils/settrans.c:184
        184               node = file_name_lookup (node_name, flags |
        lookup_flags, 0666);
        (gdb) n
        185               if (node == MACH_PORT_NULL)
        (gdb) 
        191               *underlying = node;
        (gdb) 
        192               *underlying_type = MACH_MSG_TYPE_COPY_SEND;
        (gdb) 
        194               return 0;
        (gdb) 
        service_fsys_startup (underlying_open_fn=0x11dfe4c, cookie=0x0, 
port=61, 
        timeout=60000, control=0x11dfe48, task=62)
        at ../../project/hurd/hurd-build/libfshelp/start-translator-long.c:152
        152           reply.realnodeType = realnodeType;
        (gdb) c
        Continuing.
        warning: Pid 897 died with unknown exit status, using SIGKILL.

That is all for now.

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