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.

4 files changed, 45 insertions, 12 deletions

diff --git a/console-client/kbd-repeat.c b/console-client/kbd-repeat.c
index 641520ca..d3a39d07 100644
--- a/console-client/kbd-repeat.c
+++ b/console-client/kbd-repeat.c
@@ -86,8 +86,11 @@ kbd_repeat_key (kd_event *key)
 
 static error_t
 repeater_select (struct protid *cred, mach_port_t reply,
-		 mach_msg_type_name_t replytype, int *type)
+		 mach_msg_type_name_t replytype,
+		 struct timespec *tsp, int *type)
 {
+  error_t err;
+
   if (!cred)
     return EOPNOTSUPP;
 
@@ -109,12 +112,16 @@ repeater_select (struct protid *cred, mach_port_t reply,
 	}
       
       ports_interrupt_self_on_port_death (cred, reply);
-      if (pthread_hurd_cond_wait_np (&select_alert, &global_lock))
+      err = pthread_hurd_cond_timedwait_np (&select_alert, &global_lock, tsp);
+      if (err)
 	{
 	  *type = 0;
 	  pthread_mutex_unlock (&global_lock);
 
-	  return EINTR;
+	  if (err == ETIMEDOUT)
+	    err = 0;
+
+	  return err;
 	}
     }
 }
diff --git a/console-client/pc-mouse.c b/console-client/pc-mouse.c
index 2cec2042..8be7ff1c 100644
--- a/console-client/pc-mouse.c
+++ b/console-client/pc-mouse.c
@@ -110,8 +110,11 @@ repeat_event (kd_event *evt)
 
 static error_t
 repeater_select (struct protid *cred, mach_port_t reply,
-		 mach_msg_type_name_t replytype, int *type)
+		 mach_msg_type_name_t replytype,
+		 struct timespec *tsp, int *type)
 {
+  error_t err;
+
   if (!cred)
     return EOPNOTSUPP;
 
@@ -133,12 +136,16 @@ repeater_select (struct protid *cred, mach_port_t reply,
 	}
 
       ports_interrupt_self_on_port_death (cred, reply);
-      if (pthread_hurd_cond_wait_np (&select_alert, &global_lock))
+      err = pthread_hurd_cond_timedwait_np (&select_alert, &global_lock, tsp);
+      if (err)
 	{
 	  *type = 0;
 	  pthread_mutex_unlock (&global_lock);
 
-	  return EINTR;
+	  if (err == ETIMEDOUT)
+	    err = 0;
+
+	  return err;
 	}
     }
 }
diff --git a/console-client/trans.c b/console-client/trans.c
index 67c84b4e..6949af5e 100644
--- a/console-client/trans.c
+++ b/console-client/trans.c
@@ -332,9 +332,10 @@ netfs_S_io_seek (struct protid *user, off_t offset,
 }
 
 
-error_t
-netfs_S_io_select (struct protid *user, mach_port_t reply,
-		   mach_msg_type_name_t replytype, int *type)
+static error_t
+io_select_common (struct protid *user, mach_port_t reply,
+		  mach_msg_type_name_t replytype,
+		  struct timespec *tsp, int *type)
 {
   struct node *np;
   
@@ -344,11 +345,28 @@ netfs_S_io_select (struct protid *user, mach_port_t reply,
   np = user->po->np;
   
   if (np->nn->node && np->nn->node->select)
-    return np->nn->node->select (user, reply, replytype, type);
+    return np->nn->node->select (user, reply, replytype, tsp, type);
   return EOPNOTSUPP;
 }
 
 
+error_t
+netfs_S_io_select (struct protid *user, mach_port_t reply,
+		   mach_msg_type_name_t replytype, int *type)
+{
+  return io_select_common (user, reply, replytype, NULL, type);
+}
+
+
+error_t
+netfs_S_io_select_timeout (struct protid *user, mach_port_t reply,
+			   mach_msg_type_name_t replytype,
+			   struct timespec ts, int *type)
+{
+  return io_select_common (user, reply, replytype, &ts, type);
+}
+
+
 /* Delete NAME in DIR (which is locked) for USER.  */
 error_t
 netfs_attempt_unlink (struct iouser *user, struct node *dir,
diff --git a/console-client/trans.h b/console-client/trans.h
index f781e31f..9891cf3f 100644
--- a/console-client/trans.h
+++ b/console-client/trans.h
@@ -41,9 +41,10 @@ struct consnode
 		    mach_msg_type_number_t datalen, off_t offset,
 		    mach_msg_type_number_t *amount);
 
-  /* This is exactly the same as io_select does.  */
+  /* This is exactly the same as io_select{,_timeout} do.  */
   error_t (*select) (struct protid *user, mach_port_t reply,
-		     mach_msg_type_name_t replytype, int *type);
+		     mach_msg_type_name_t replytype,
+		     struct timespec *tsp, int *type);
 
   /* Called when the node is opened.  */
   void (*open) (void);