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.

3 files changed, 77 insertions, 22 deletions

diff --git a/pfinet/glue-include/linux/sched.h b/pfinet/glue-include/linux/sched.h
index aea6c47a..26ab10a8 100644
--- a/pfinet/glue-include/linux/sched.h
+++ b/pfinet/glue-include/linux/sched.h
@@ -8,6 +8,7 @@
 #include <limits.h>
 #include <assert.h>
 #include <pthread.h>
+#include <errno.h>
 
 #include "mapped-time.h"
 
@@ -92,12 +93,13 @@ capable(int cap)
 
 extern pthread_mutex_t global_lock;
 
-static inline void
-interruptible_sleep_on (struct wait_queue **p)
+static inline int
+interruptible_sleep_on_timeout (struct wait_queue **p, struct timespec *tsp)
 {
   pthread_cond_t **condp = (void *) p, *c;
   int isroot;
   struct wait_queue **next_wait;
+  error_t err;
 
   c = *condp;
   if (c == 0)
@@ -111,12 +113,13 @@ interruptible_sleep_on (struct wait_queue **p)
   isroot = current->isroot;	/* This is our context that needs switched.  */
   next_wait = current->next_wait; /* This too, for multiple schedule calls.  */
   current->next_wait = 0;
-  if (pthread_hurd_cond_wait_np (c, &global_lock))
+  err = pthread_hurd_cond_timedwait_np(c, &global_lock, tsp);
+  if (err == EINTR)
     current->signal = 1;	/* We got cancelled, mark it for later.  */
   current->isroot = isroot;	/* Switch back to our context.  */
   current->next_wait = next_wait;
+  return (err == ETIMEDOUT);
 }
-#define sleep_on	interruptible_sleep_on
 
 static inline void
 wake_up_interruptible (struct wait_queue **p)
@@ -146,7 +149,7 @@ static inline void
 schedule (void)
 {
   assert (current->next_wait);
-  interruptible_sleep_on (current->next_wait);
+  interruptible_sleep_on_timeout (current->next_wait, NULL);
 }
 
 static inline void
@@ -171,7 +174,7 @@ schedule_timeout (long timeout)
   timer.function = process_schedule_timeout;
   add_timer (&timer);
 
-  interruptible_sleep_on (&sleep);
+  interruptible_sleep_on_timeout (&sleep, NULL);
   if (signal_pending (current))
     {
       /* We were canceled.  */
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)
 {
diff --git a/pfinet/tunnel.c b/pfinet/tunnel.c
index 5d2544b2..4a6f616a 100644
--- a/pfinet/tunnel.c
+++ b/pfinet/tunnel.c
@@ -462,13 +462,14 @@ trivfs_S_io_readable (struct trivfs_protid *cred,
    return the types that are then available.  ID_TAG is returned as passed; it
    is just for the convenience of the user in matching up reply messages with
    specific requests sent.  */
-error_t
-trivfs_S_io_select (struct trivfs_protid *cred,
-                    mach_port_t reply,
-                    mach_msg_type_name_t reply_type,
-                    int *type)
+static error_t
+io_select_common (struct trivfs_protid *cred,
+		  mach_port_t reply,
+		  mach_msg_type_name_t reply_type,
+		  struct timespec *tsp, int *type)
 {
   struct tunnel_device *tdev;
+  error_t err;
 
   if (!cred)
     return EOPNOTSUPP;
@@ -497,15 +498,40 @@ trivfs_S_io_select (struct trivfs_protid *cred,
 
       ports_interrupt_self_on_port_death (cred, reply);
       tdev->read_blocked = 1;
-      if (pthread_hurd_cond_wait_np (&tdev->select_alert, &tdev->lock))
+      err = pthread_hurd_cond_timedwait_np (&tdev->select_alert, &tdev->lock,
+					    tsp);
+      if (err)
         {
           *type = 0;
           pthread_mutex_unlock (&tdev->lock);
-          return EINTR;
+
+          if (err == ETIMEDOUT)
+            err = 0;
+
+          return err;
         }
     }
 }
 
+error_t
+trivfs_S_io_select (struct trivfs_protid *cred,
+                    mach_port_t reply,
+                    mach_msg_type_name_t reply_type,
+                    int *type)
+{
+  return io_select_common (cred, reply, reply_type, NULL, type);
+}
+
+error_t
+trivfs_S_io_select_timeout (struct trivfs_protid *cred,
+			    mach_port_t reply,
+			    mach_msg_type_name_t reply_type,
+			    struct timespec ts,
+			    int *type)
+{
+  return io_select_common (cred, reply, reply_type, &ts, type);
+}
+
 /* Change current read/write offset */
 error_t
 trivfs_S_io_seek (struct trivfs_protid *cred,