diff -rdN -bB -U 3 linux/fs/fcntl.c linux-2.4.4.onesigfd/fs/fcntl.c
--- linux/fs/fcntl.c	Wed Nov 15 22:50:25 2000
+++ linux-2.4.4.onesigfd/fs/fcntl.c	Fri May 18 16:02:17 2001
@@ -300,6 +300,13 @@
 		case F_NOTIFY:
 			err = fcntl_dirnotify(fd, filp, arg);
 			break;
+                case F_GETAUXFL:
+                        err = filp->f_auxflags;
+                        break;
+                case F_SETAUXFL:
+                        filp->f_auxflags = arg;
+                        err = 0;
+                        break;
 		default:
 			/* sockets need a few special fcntls. */
 			err = -EINVAL;
diff -rdN -bB -U 3 linux/fs/file_table.c linux-2.4.4.onesigfd/fs/file_table.c
--- linux/fs/file_table.c	Wed Apr 18 11:49:12 2001
+++ linux-2.4.4.onesigfd/fs/file_table.c	Fri May 18 16:02:17 2001
@@ -109,6 +109,8 @@
 		fops_put(file->f_op);
 		file->f_dentry = NULL;
 		file->f_vfsmnt = NULL;
+                file->f_auxflags = 0;
+                file->f_infoptr  = NULL; /* Should this be dequeued ? */
 		if (file->f_mode & FMODE_WRITE)
 			put_write_access(inode);
 		dput(dentry);
diff -rdN -bB -U 3 linux/include/linux/fcntl.h linux-2.4.4.onesigfd/include/linux/fcntl.h
--- linux/include/linux/fcntl.h	Fri Sep 22 14:21:22 2000
+++ linux-2.4.4.onesigfd/include/linux/fcntl.h	Fri May 18 16:02:17 2001
@@ -12,6 +12,11 @@
  */
 #define F_NOTIFY	(F_LINUX_SPECIFIC_BASE+2)
 
+/* Request only one rt-signal per fd discipline
+ */
+#define F_SETAUXFL      (F_LINUX_SPECIFIC_BASE+3)
+#define F_GETAUXFL      (F_LINUX_SPECIFIC_BASE+4)
+
 /*
  * Types of directory notifications that may be requested.
  */
@@ -22,5 +27,11 @@
 #define DN_RENAME	0x00000010	/* File renamed */
 #define DN_ATTRIB	0x00000020	/* File changed attibutes */
 #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
+
+/*
+ * Auxillary flags
+ */
+#define O_ONESIGFD      (2<<17)         /* Allow only one rt signal */
+                                        /* per fd in sigqueue       */
 
 #endif
diff -rdN -bB -U 3 linux/include/linux/fs.h linux-2.4.4.onesigfd/include/linux/fs.h
--- linux/include/linux/fs.h	Fri Apr 27 15:48:28 2001
+++ linux-2.4.4.onesigfd/include/linux/fs.h	Fri May 18 16:02:17 2001
@@ -486,6 +486,8 @@
 	int			f_error;
 
 	unsigned long		f_version;
+        unsigned int            f_auxflags;
+        void                    *f_infoptr;
 
 	/* needed for tty driver, and maybe others */
 	void			*private_data;
diff -rdN -bB -U 3 linux/kernel/signal.c linux-2.4.4.onesigfd/kernel/signal.c
--- linux/kernel/signal.c	Wed Jan  3 20:45:26 2001
+++ linux-2.4.4.onesigfd/kernel/signal.c	Fri May 18 16:02:17 2001
@@ -13,6 +13,7 @@
 #include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/sched.h>
+#include <linux/file.h>
 
 #include <asm/uaccess.h>
 
@@ -203,6 +204,17 @@
 		if ((*pp = q->next) == NULL)
 			list->tail = pp;
 
+                /* For one signal per fd discipline, indicate signal
+                 * delivery so a new one can be queued
+                 */
+                if (sig >= SIGRTMIN) {
+                    struct file *filep = fcheck( q->info.si_fd );
+
+                    if( filep && (filep->f_auxflags & O_ONESIGFD) &&
+                        ( q == (siginfo_t *) filep->f_infoptr ) )
+                        filep->f_infoptr = NULL;
+                }
+
 		/* Copy the sigqueue information and free the queue entry */
 		copy_siginfo(info, &q->info);
 		kmem_cache_free(sigqueue_cachep,q);
@@ -399,9 +411,31 @@
 	}
 }
 
-static int send_signal(int sig, struct siginfo *info, struct sigpending *signals)
+static int send_signal(int sig, struct siginfo *info, struct task_struct *t)
 {
-	struct sigqueue * q = NULL;
+        struct sigqueue   *q         = NULL;
+        struct sigpending *signals   = &t->pending ;
+        unsigned int       newsignal = 0;
+        struct file       *filep     = NULL;
+
+        if( (sig >= SIGRTMIN) && ( (unsigned long) info > 1) ) {
+            struct files_struct * files = t->files;
+
+            if( (info->si_fd < files->max_fds) &&
+                ( filep = files->fd[ info->si_fd ] ) &&
+                ( filep->f_auxflags & O_ONESIGFD ) ) {
+                if( filep->f_infoptr ){
+                    /* signal is already queued for this fd
+                       but the reason for signal may be different*/
+                    q = ( struct sigqueue *) filep->f_infoptr;
+                    q->info.si_band |= info->si_band;
+                    return 0; 
+                }
+                else
+                    newsignal = 1;
+            }
+        }
+
 
 	/* Real-time signals must be queued if sent by sigqueue, or
 	   some other real-time mechanism.  It is implementation
@@ -415,6 +449,11 @@
 		q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
 	}
 
+        /* Set a reference for signal queued in fd for
+           one-signal-per-fd discipline */
+        if( newsignal && q )
+            filep->f_infoptr = q;
+
 	if (q) {
 		atomic_inc(&nr_queued_signals);
 		q->next = NULL;
@@ -492,7 +531,7 @@
 
 static int deliver_signal(int sig, struct siginfo *info, struct task_struct *t)
 {
-	int retval = send_signal(sig, info, &t->pending);
+	int retval = send_signal(sig, info, t);
 
 	if (!retval && !sigismember(&t->blocked, sig))
 		signal_wake_up(t);