diff options
| -rw-r--r-- | hurd/dtable.c | 46 |
1 files changed, 39 insertions, 7 deletions
diff --git a/hurd/dtable.c b/hurd/dtable.c index 5dd0413191..41f4d7afef 100644 --- a/hurd/dtable.c +++ b/hurd/dtable.c @@ -60,18 +60,50 @@ init_dtable (void) _hurd_dtable[i] = NULL; else { + int copy; /* Allocate a new file descriptor structure. */ struct hurd_fd *new = malloc (sizeof (struct hurd_fd)); if (new == NULL) __libc_fatal ("hurd: Can't allocate initial file descriptors\n"); - /* Initialize the port cells. */ - _hurd_port_init (&new->port, MACH_PORT_NULL); - _hurd_port_init (&new->ctty, MACH_PORT_NULL); - - /* Install the port in the descriptor. - This sets up all the ctty magic. */ - _hurd_port2fd (new, _hurd_init_dtable[i], 0); + /* See if this file descriptor is the same as a previous one we have + already installed. In this case, we can just copy over the same + ctty port without making any more RPCs. We only check the the + immediately preceding fd and fd 0 -- this should be enough to + handle the common cases while not requiring quadratic + complexity. */ + if (i > 0 && _hurd_init_dtable[i] == _hurd_init_dtable[i - 1]) + copy = i - 1; + else if (i > 0 && _hurd_init_dtable[i] == _hurd_init_dtable[0]) + copy = 0; + else + copy = -1; + + if (copy < 0) + { + /* Initialize the port cells. */ + _hurd_port_init (&new->port, MACH_PORT_NULL); + _hurd_port_init (&new->ctty, MACH_PORT_NULL); + + /* Install the port in the descriptor. + This sets up all the ctty magic. */ + _hurd_port2fd (new, _hurd_init_dtable[i], 0); + } + else + { + /* Copy over ctty from the already set up file descriptor that + contains the same port. We can access the contents of the + cell without any locking since no one could have seen it + yet. */ + mach_port_t ctty = _hurd_dtable[copy]->ctty.port; + + if (MACH_PORT_VALID (ctty)) + __mach_port_mod_refs (__mach_task_self (), ctty, + MACH_PORT_RIGHT_SEND, +1); + + _hurd_port_init (&new->port, _hurd_init_dtable[i]); + _hurd_port_init (&new->ctty, ctty); + } _hurd_dtable[i] = new; } |