Add io_select_timeout to the io interface

This change fixes a problem that can occur with non-blocking (and also
blocking for very short times) select/poll calls. The problem occurs because
the timeout is implemented at the client side. For a non-blocking call, this
means that (depending on the code path taken in the C library) the client
could get a timeout without a full RPC round-trip to the server. Moving the
implementation of the timeout to the servers guarantees a full round-trip,
and correct results for non-blocking calls.

The modifications in this change depend on the availability of the recently
added pthread_hurd_cond_timedwait_np function in libpthread.

* boot/boot.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* console-client/kbd-repeat.c (repeater_select): Add a timeout parameter.
* console-client/pc-mouse.c (repeater_select): Likewise.
* console-client/trans.c (io_select_common): New static function.
(netfs_S_io_select): Use io_select_common.
(netfs_S_io_select_timeout): New function which makes use of io_select_common.
* console-client/trans.h (struct consnode): Add a timeout parameter.
* hurd/io.defs (io_select_timeout): New MIG routine.
* hurd/io_reply.defs (io_select_timeout_reply): New MIG simpleroutine.
* hurd/io_request.defs (io_select_timeout_request): Likewise.
* libdiskfs/io-select.c (diskfs_S_io_select_timeout): New function.
* libnetfs/io-select.c (netfs_S_io_select_timeout): Likewise.
* libpipe/pipe.c (pipe_pair_select): Add a timeout parameter.
* libpipe/pipe.h (pipe_select_readable): Likewise.
(pipe_select_writable): Likewise.
(pipe_pair_select): Likewise.
* libpipe/pq.h: Include <hurd/hurd_types.h>.
* libtrivfs/io-select.c (trivfs_S_io_select_timeout): New function.
* pfinet/glue-include/linux/sched.h: Include <errno.h>.
(interruptible_sleep_on): Function removed, replaced with ...
(interruptible_sleep_on_timeout): New function.
(schedule): Update to use interruptible_sleep_on_timeout.
(schedule_timeout): Likewise.
* pfinet/io-ops.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* pfinet/tunnel.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* pflocal/connq.c (connq_listen): Replace noblock with a timeout parameter.
* pflocal/connq.h: Include <hurd/hurd_types.h>.
(connq_listen): Update declaration to replace noblock with a timeout parameter.
* pflocal/io.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* pflocal/socket.c (S_socket_accept): Update call to connq_listen to match new
declaration.
* storeio/io.c (trivfs_S_io_select_timeout): New function.
* term/ptyio.c (pty_io_select): Add a timeout parameter.
* term/term.h (pty_io_select): Likewise.
* term/users.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/fifo.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/firmlink.c (trivfs_S_io_select_timeout): New function.
* trans/new-fifo.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/null.c (trivfs_S_io_select_timeout): New function.
* trans/streamio.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.

1 files changed, 35 insertions, 9 deletions

diff --git a/pfinet/io-ops.c b/pfinet/io-ops.c
index 5f3b1e90..69bd93c5 100644
--- a/pfinet/io-ops.c
+++ b/pfinet/io-ops.c
@@ -251,14 +251,14 @@ S_io_clear_some_openmodes (struct sock_user *user,
   return 0;
 }
 
-error_t
-S_io_select (struct sock_user *user,
-	     mach_port_t reply,
-	     mach_msg_type_name_t reply_type,
-	     int *select_type)
+static error_t
+io_select_common (struct sock_user *user,
+		  mach_port_t reply,
+		  mach_msg_type_name_t reply_type,
+		  struct timespec *tsp, int *select_type)
 {
   const int want = *select_type | POLLERR;
-  int avail;
+  int avail, timedout;
   int ret = 0;
 
   if (!user)
@@ -281,9 +281,16 @@ S_io_select (struct sock_user *user,
 
       do
 	{
-	  /* Block until we are woken or cancelled.  */
-	  interruptible_sleep_on (user->sock->sk->sleep);
-	  if (signal_pending (current)) /* This means we were cancelled.  */
+	  /* Block until we time out, are woken or cancelled.  */
+	  timedout = interruptible_sleep_on_timeout (user->sock->sk->sleep,
+						     tsp);
+	  if (timedout)
+	    {
+	      __mutex_unlock (&global_lock);
+	      *select_type = 0;
+	      return 0;
+	    }
+	  else if (signal_pending (current)) /* This means we were cancelled.  */
 	    {
 	      pthread_mutex_unlock (&global_lock);
 	      return EINTR;
@@ -307,6 +314,25 @@ S_io_select (struct sock_user *user,
 }
 
 error_t
+S_io_select (struct sock_user *user,
+	     mach_port_t reply,
+	     mach_msg_type_name_t reply_type,
+	     int *select_type)
+{
+  return io_select_common (user, reply, reply_type, NULL, select_type);
+}
+
+error_t
+S_io_select_timeout (struct sock_user *user,
+		     mach_port_t reply,
+		     mach_msg_type_name_t reply_type,
+		     struct timespec ts,
+		     int *select_type)
+{
+  return io_select_common (user, reply, reply_type, &ts, select_type);
+}
+
+error_t
 S_io_stat (struct sock_user *user,
 	   struct stat *st)
 {