Re: [PATCH hurd 7/7] proc: call `startup_essential_task' earlier

[Samuel Thibault]

Justus Winter, le Sat 17 Jan 2015 18:26:46 +0100, a écrit :
> Previously, the proc server did not call `startup_essential_task'
> until it got the message port of the startup server using
> `proc_setmsgport'.
> 
> Now that we have `/servers/startup', we can do this in main, before we
> start our message service loop.
> 
> A complication arises because the traditional startup server is
> single-threaded.  Handle this by tweaking startup not to bind itself
> to `/servers/startup' before it is ready.

Ack, thanks!

> * proc/main.c (main): Try to lookup `/servers/startup' and send the
> message here, or...
> * proc/msg.c (S_proc_setmsgport): ... fall back to the old way here.
> * proc/proc.h (startup_fallback): New variable.
> * startup/startup.c (main): Move code installing ourself on `/servers/startup'
> (install_as_translator): ... here.
> (launch_core_servers): And use it here, just before we reply to `/hurd/auth'.
> ---
>  proc/main.c       | 23 +++++++++++++++++++++++
>  proc/msg.c        |  2 +-
>  proc/proc.h       |  2 ++
>  startup/startup.c | 44 ++++++++++++++++++++++++++++++++------------
>  4 files changed, 58 insertions(+), 13 deletions(-)
> 
> diff --git a/proc/main.c b/proc/main.c
> index b4288fb..6df4141 100644
> --- a/proc/main.c
> +++ b/proc/main.c
> @@ -22,6 +22,7 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 
> 02139, USA.  */
>  #include <mach.h>
>  #include <hurd/hurd_types.h>
>  #include <hurd.h>
> +#include <hurd/paths.h>
>  #include <hurd/startup.h>
>  #include <device/device.h>
>  #include <assert.h>
> @@ -62,6 +63,7 @@ message_demuxer (mach_msg_header_t *inp,
>  }
>  
>  pthread_mutex_t global_lock = PTHREAD_MUTEX_INITIALIZER;
> +int startup_fallback;
>  
>  error_t
>  increase_priority (void)
> @@ -99,6 +101,7 @@ main (int argc, char **argv, char **envp)
>    error_t err;
>    void *genport;
>    process_t startup_port;
> +  mach_port_t startup;
>    struct argp argp = { 0, 0, 0, "Hurd process server" };
>  
>    argp_parse (&argp, argc, argv, 0, 0, 0);
> @@ -173,6 +176,26 @@ main (int argc, char **argv, char **envp)
>      mach_port_deallocate (mach_task_self (), cons);
>    }
>  
> +  startup = file_name_lookup (_SERVERS_STARTUP, 0, 0);
> +  if (MACH_PORT_VALID (startup))
> +    {
> +      err = startup_essential_task (startup, mach_task_self (),
> +                                 MACH_PORT_NULL, "proc", _hurd_host_priv);
> +      if (err)
> +     /* Due to the single-threaded nature of /hurd/startup, it can
> +        only handle requests once the core server bootstrap has
> +        completed.  Therefore, it does not bind itself to
> +        /servers/startup until it is ready.  */
> +     /* Fall back to abusing the message port lookup.  */
> +     startup_fallback = 1;
> +
> +      err = mach_port_deallocate (mach_task_self (), startup);
> +      assert_perror (err);
> +    }
> +  else
> +    /* Fall back to abusing the message port lookup. */
> +    startup_fallback = 1;
> +
>    while (1)
>      ports_manage_port_operations_multithread (proc_bucket,
>                                             message_demuxer,
> diff --git a/proc/msg.c b/proc/msg.c
> index 796cae3..c7bab99 100644
> --- a/proc/msg.c
> +++ b/proc/msg.c
> @@ -63,7 +63,7 @@ S_proc_setmsgport (struct proc *p,
>      prociterate (check_message_return, p);
>    p->p_checkmsghangs = 0;
>  
> -  if (p == startup_proc)
> +  if (p == startup_proc && startup_fallback)
>      {
>      /* Init is single threaded, so we can't delay our reply for
>         the essential task RPC; spawn a thread to do it. */
> diff --git a/proc/proc.h b/proc/proc.h
> index a056d18..4be1de4 100644
> --- a/proc/proc.h
> +++ b/proc/proc.h
> @@ -151,6 +151,8 @@ mach_port_t generic_port; /* messages not related to a 
> specific proc */
>  
>  pthread_mutex_t global_lock;
>  
> +extern int startup_fallback; /* (ab)use /hurd/startup's message port */
> +
>  /* Forward declarations */
>  void complete_wait (struct proc *, int);
>  int check_uid (struct proc *, uid_t);
> diff --git a/startup/startup.c b/startup/startup.c
> index c9fe215..e01d2a8 100644
> --- a/startup/startup.c
> +++ b/startup/startup.c
> @@ -514,6 +514,32 @@ demuxer (mach_msg_header_t *inp,
>         startup_server (inp, outp));
>  }
>  
> +error_t
> +install_as_translator (void)
> +{
> +  error_t err;
> +  file_t node;
> +
> +  node = file_name_lookup (_SERVERS_STARTUP, O_NOTRANS, 0);
> +  if (! MACH_PORT_VALID (node))
> +    {
> +      if (errno == ENOENT)
> +     {
> +       /* Degrade gracefully if the node does not exist.  */
> +       error (0, errno, "%s", _SERVERS_STARTUP);
> +       return 0;
> +     }
> +      return errno;
> +    }
> +
> +  err = file_set_translator (node,
> +                          0, FS_TRANS_SET, 0,
> +                          NULL, 0,
> +                          startup, MACH_MSG_TYPE_COPY_SEND);
> +  mach_port_deallocate (mach_task_self (), node);
> +  return err;
> +}
> +
>  static int
>  parse_opt (int key, char *arg, struct argp_state *state)
>  {
> @@ -587,18 +613,6 @@ main (int argc, char **argv, char **envp)
>    /* Crash if the boot filesystem task dies.  */
>    request_dead_name (fstask);
>  
> -  file_t node = file_name_lookup (_SERVERS_STARTUP, O_NOTRANS, 0);
> -  if (node == MACH_PORT_NULL)
> -    error (0, errno, "%s", _SERVERS_STARTUP);
> -  else
> -    {
> -      file_set_translator (node,
> -                        0, FS_TRANS_SET, 0,
> -                        NULL, 0,
> -                        startup, MACH_MSG_TYPE_COPY_SEND);
> -      mach_port_deallocate (mach_task_self (), node);
> -    }
> -
>    /* Set up the set of ports we will pass to the programs we exec.  */
>    for (i = 0; i < INIT_PORT_MAX; i++)
>      switch (i)
> @@ -672,6 +686,12 @@ launch_core_servers (void)
>    proc_task2proc (procserver, authtask, &authproc);
>    proc_mark_important (authproc);
>    proc_mark_exec (authproc);
> +
> +  err = install_as_translator ();
> +  if (err)
> +    /* Good luck.  Who knows, maybe it's an old installation.  */
> +    error (0, err, "Failed to bind to " _SERVERS_STARTUP);
> +
>    startup_authinit_reply (authreply, authreplytype, 0, authproc,
>                         MACH_MSG_TYPE_COPY_SEND);
>    mach_port_deallocate (mach_task_self (), authproc);
> -- 
> 2.1.4
> 

-- 
Samuel
* x remarque qu'avec un peu de volonté, on peut faire du code de porc
dans d'importe quel langage Turing-complet
 -+- x sur #ens-mim - codons porc -+-