From 1d19665b79fcbc99d90d3a660a43a1c5dc6a2365 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Mon, 22 Oct 2012 13:55:49 -0700
Subject: [PATCH] tapset: Add the macro @choose_defined and use it

This returns the first parameter if it's @defined, otherwise it returns
the second parameter, replacing the common @defined(x)?x:y pattern.

I only updated the tapsets to use this, as I feel that's where we should
show off good code practice.  There are opportunities in the testsuite
that could use it too, but it's not necessary, and probably better to
leave existing tests undisturbed when possible.
---
 tapset/choose_defined.stpm       |   4 ++
 tapset/linux/dentry.stp          |  10 ++--
 tapset/linux/i386/syscalls.stp   |   4 +-
 tapset/linux/inet_sock.stp       |   8 +--
 tapset/linux/ioblock.stp         |   8 +--
 tapset/linux/ioscheduler.stp     |  89 +++++++++++++--------------
 tapset/linux/ip.stp              |  22 +++----
 tapset/linux/ipmib.stp           |  16 ++---
 tapset/linux/irq.stp             |  12 ++--
 tapset/linux/linuxmib.stp        |   2 +-
 tapset/linux/memory.stp          |   8 +--
 tapset/linux/networking.stp      |   2 +-
 tapset/linux/nfs.stp             |  14 ++---
 tapset/linux/nfs_proc.stp        |  11 ++--
 tapset/linux/nfsd.stp            |  14 ++---
 tapset/linux/rpc.stp             |  45 +++++---------
 tapset/linux/scheduler.stp       |   4 +-
 tapset/linux/scsi.stp            |  15 +++--
 tapset/linux/signal.stp          |   8 +--
 tapset/linux/socket.stp          |   4 +-
 tapset/linux/syscalls.stp        | 100 +++++++++++++++----------------
 tapset/linux/syscalls2.stp       |  54 ++++++++---------
 tapset/linux/task.stp            |  12 ++--
 tapset/linux/tcp.stp             |  20 +++----
 tapset/linux/tcpmib.stp          |   2 +-
 tapset/linux/tty.stp             |  24 ++++----
 tapset/linux/vfs.stp             |  13 ++--
 tapset/linux/x86_64/syscalls.stp |   2 +-
 28 files changed, 237 insertions(+), 290 deletions(-)
 create mode 100644 tapset/choose_defined.stpm

diff --git a/tapset/choose_defined.stpm b/tapset/choose_defined.stpm
new file mode 100644
index 000000000..60800951d
--- /dev/null
+++ b/tapset/choose_defined.stpm
@@ -0,0 +1,4 @@
+// Use the first parameter if it's @defined, otherwise use the second parameter
+@define choose_defined(value_if_defined, alternate) %(
+	( @defined(@value_if_defined) ? (@value_if_defined) : (@alternate) )
+%)
diff --git a/tapset/linux/dentry.stp b/tapset/linux/dentry.stp
index 7b4bfdb99..035bbe39e 100644
--- a/tapset/linux/dentry.stp
+++ b/tapset/linux/dentry.stp
@@ -181,12 +181,10 @@ function task_dentry_path:string(task:long,dentry:long,vfsmnt:long)
  */
 function d_path:string(nd:long)
 {
-	dentry = (@defined(@cast(nd,"nameidata")->path->dentry)
-	    ? @cast(nd,"nameidata")->path->dentry
-	    : @cast(nd,"nameidata")->dentry)
-	vfsmnt = (@defined(@cast(nd,"nameidata")->path->mnt)
-	    ? @cast(nd,"nameidata")->path->mnt
-	    : @cast(nd,"nameidata")->mnt)
+	dentry = @choose_defined(@cast(nd,"nameidata")->path->dentry,
+			         @cast(nd,"nameidata")->dentry)
+	vfsmnt = @choose_defined(@cast(nd,"nameidata")->path->mnt,
+			         @cast(nd,"nameidata")->mnt)
 
 	return sprintf("%s/", task_dentry_path(task_current(), dentry, vfsmnt))
 }
diff --git a/tapset/linux/i386/syscalls.stp b/tapset/linux/i386/syscalls.stp
index e1990bdb9..9be16d5b8 100644
--- a/tapset/linux/i386/syscalls.stp
+++ b/tapset/linux/i386/syscalls.stp
@@ -139,8 +139,8 @@ probe syscall.sigaltstack = kernel.function("sys_sigaltstack")
 	ussp = %( kernel_vr < "2.6.25" %? $ebx %: %( kernel_vr < "2.6.30" %? $bx %: $regs->bx %) %)
 %)
 	if (@defined($regs)) {
-		uss_uaddr = (@defined($uss) ? $uss : $regs->bx)
-		uoss_uaddr = (@defined($uoss) ? $uoss : $regs->cx)
+		uss_uaddr = @choose_defined($uss, $regs->bx)
+		uoss_uaddr = @choose_defined($uoss, $regs->cx)
 		regs = $regs
 	}
 	else if (@defined($bx)) {	# kernels < "2.6.30"
diff --git a/tapset/linux/inet_sock.stp b/tapset/linux/inet_sock.stp
index fda46fb63..72b2be7de 100644
--- a/tapset/linux/inet_sock.stp
+++ b/tapset/linux/inet_sock.stp
@@ -14,11 +14,9 @@
  */
 function inet_get_local_port:long(sock:long)
 {
-    return (@defined(@cast(sock, "inet_sock")->inet_num)
-	    ? @cast(sock, "inet_sock")->inet_num # kernel >= 2.6.33
-	    : (@defined(@cast(sock, "inet_sock")->num)
-	       ? @cast(sock, "inet_sock", "kernel")->num # kernel >= 2.6.11
-	       : @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->num))
+    return @choose_defined(@cast(sock, "inet_sock")->inet_num, # kernel >= 2.6.33
+            @choose_defined(@cast(sock, "inet_sock")->num, # kernel >= 2.6.11
+                @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->num))
 }
 
 /**
diff --git a/tapset/linux/ioblock.stp b/tapset/linux/ioblock.stp
index 40bfd1a82..2d1577fe2 100644
--- a/tapset/linux/ioblock.stp
+++ b/tapset/linux/ioblock.stp
@@ -109,8 +109,7 @@ probe ioblock.request = kernel.function ("generic_make_request")
         vcnt = $bio->bi_vcnt
         idx = $bio->bi_idx
         phys_segments = $bio->bi_phys_segments
-	hw_segments = (@defined($bio->bi_hw_segments)
-		       ? $bio->bi_hw_segments : 0)
+	hw_segments = @choose_defined($bio->bi_hw_segments, 0)
         size = $bio->bi_size
 
         bdev = $bio->bi_bdev
@@ -152,7 +151,7 @@ probe ioblock.end = kernel.function("bio_endio")
         devname = __bio_devname($bio)
         ino = __bio_ino($bio)
 
-        bytes_done = (@defined($bytes_done) ? $bytes_done : $bio->bi_size)
+        bytes_done = @choose_defined($bytes_done, $bio->bi_size)
         error = $error
 
         sector = $bio->bi_sector
@@ -161,8 +160,7 @@ probe ioblock.end = kernel.function("bio_endio")
         vcnt = $bio->bi_vcnt
         idx = $bio->bi_idx
         phys_segments = $bio->bi_phys_segments
-	hw_segments = (@defined($bio->bi_hw_segments)
-		       ? $bio->bi_hw_segments : 0)
+	hw_segments = @choose_defined($bio->bi_hw_segments, 0)
         size = $bio->bi_size
 }
 
diff --git a/tapset/linux/ioscheduler.stp b/tapset/linux/ioscheduler.stp
index e90bf7aee..842e27e6a 100644
--- a/tapset/linux/ioscheduler.stp
+++ b/tapset/linux/ioscheduler.stp
@@ -23,11 +23,10 @@ probe ioscheduler.elv_next_request = kernel.function("blk_peek_request") !,
 				     kernel.function("elv_next_request")
 {
 	name = "elv_next_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 }
 
 /**
@@ -50,8 +49,7 @@ probe ioscheduler.elv_next_request.return =
 		disk_minor = -1
 	} else {
 		rq = $return
-		rq_flags = (@defined($return->cmd_flags) ? $return->cmd_flags
-			: $return->flags)
+		rq_flags = @choose_defined($return->cmd_flags, $return->flags)
 		if ($return->rq_disk == 0)  {
 			disk_major = -1
 			disk_minor = -1
@@ -75,11 +73,10 @@ probe ioscheduler.elv_completed_request
 	= kernel.function("elv_completed_request")
 {
 	name = "elv_completed_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	if($rq == 0)  {
 		disk_major = -1
 		disk_minor = -1
@@ -95,7 +92,7 @@ probe ioscheduler.elv_completed_request
 
 	rq = $rq
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -114,11 +111,10 @@ probe ioscheduler.elv_add_request.kp =
 		kernel.function("__elv_add_request")
 {
 	name = "elv_add_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	q = $q
 	if($rq == 0)  {
 		disk_major = -1
@@ -135,7 +131,7 @@ probe ioscheduler.elv_add_request.kp =
 
 	rq = $rq
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -153,11 +149,10 @@ probe ioscheduler.elv_add_request.tp = kernel.trace("block_rq_insert") ?
 {
 	name = "elv_add_request"
 	q =  $q
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	rq = $rq
 
 	if ($rq == 0 || $rq->rq_disk ==0) {
@@ -170,7 +165,7 @@ probe ioscheduler.elv_add_request.tp = kernel.trace("block_rq_insert") ?
 	}
 
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -202,11 +197,10 @@ probe ioscheduler_trace.elv_completed_request
 			= kernel.trace("block_rq_complete") ?
 {
 	name = "elv_completed_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	rq = $rq
 
 	if ($rq == 0 || $rq->rq_disk ==0) {
@@ -219,7 +213,7 @@ probe ioscheduler_trace.elv_completed_request
 	}
 
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -237,11 +231,10 @@ probe ioscheduler_trace.elv_issue_request
 			= kernel.trace("block_rq_issue") ?
 {
 	name = "elv_issue_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	rq = $rq
 
 	if ($rq == 0 || $rq->rq_disk ==0) {
@@ -254,7 +247,7 @@ probe ioscheduler_trace.elv_issue_request
 	}
 
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -272,11 +265,10 @@ probe ioscheduler_trace.elv_requeue_request
 			= kernel.trace("block_rq_requeue") ?
 {
 	name = "elv_requeue_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	rq = $rq
 
 	if ($rq == 0 || $rq->rq_disk ==0) {
@@ -289,7 +281,7 @@ probe ioscheduler_trace.elv_requeue_request
 	}
 
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
@@ -306,11 +298,10 @@ probe ioscheduler_trace.elv_abort_request
 			= kernel.trace("block_rq_abort") ?
 {
 	name = "elv_abort_request"
-	elevator_name = kernel_string(@defined($q->elevator->type)
-		? $q->elevator->type->elevator_name 
-		: (@defined($q->elevator->elevator_type)
-		   ? $q->elevator->elevator_type->elevator_name
-		   : $q->elevator->elevator_name))
+	elevator_name = kernel_string(
+		@choose_defined($q->elevator->type->elevator_name,
+			@choose_defined($q->elevator->elevator_type->elevator_name,
+				$q->elevator->elevator_name)))
 	rq = $rq
 
 	if ($rq == 0 || $rq->rq_disk ==0) {
@@ -323,7 +314,7 @@ probe ioscheduler_trace.elv_abort_request
 	}
 
 	rq_flags = ($rq == 0) ? 0
-		: (@defined($rq->cmd_flags) ? $rq->cmd_flags : $rq->flags)
+		: @choose_defined($rq->cmd_flags, $rq->flags)
 }
 
 /**
diff --git a/tapset/linux/ip.stp b/tapset/linux/ip.stp
index 133790e91..b1eea666d 100644
--- a/tapset/linux/ip.stp
+++ b/tapset/linux/ip.stp
@@ -84,12 +84,9 @@ function __ip_sock_saddr:long (sock:long)
 {
     family = @cast(sock, "inet_sock", "kernel<net/ip.h>")->sk->__sk_common->skc_family
     if (family == %{ /* pure */ /* unprivileged */ AF_INET %}) {
-	return (@defined(@cast(sock, "inet_sock")->inet_saddr)
-		? @cast(sock, "inet_sock")->inet_saddr # kernel >= 2.6.33
-		: (@defined(@cast(sock, "inet_sock")->saddr)
-		  ? # kernel >= 2.6.11
-		    @cast(sock, "inet_sock", "kernel")->saddr
-		  : @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->saddr))
+	return @choose_defined(@cast(sock, "inet_sock")->inet_saddr, # kernel >= 2.6.33
+		@choose_defined(@cast(sock, "inet_sock")->saddr, # kernel >= 2.6.11
+		    @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->saddr))
     }
 %( CONFIG_IPV6 == "[ym]" %?
     else if (family == %{ /* pure */ /* unprivileged */ AF_INET6 %}) {
@@ -104,15 +101,10 @@ function __ip_sock_daddr:long (sock:long)
 {
     family = @cast(sock, "inet_sock", "kernel<net/ip.h>")->sk->__sk_common->skc_family
     if (family == %{ /* pure */ /* unprivileged */ AF_INET %}) {
-	return (@defined(@cast(sock, "inet_sock")->sk->__sk_common->skc_daddr)
-		? # kernel >= 2.6.38
-		  @cast(sock, "inet_sock")->sk->__sk_common->skc_daddr
-		: (@defined(@cast(sock, "inet_sock")->inet_daddr)
-		  ? @cast(sock, "inet_sock")->inet_daddr # kernel >= 2.6.33
-		  : (@defined(@cast(sock, "inet_sock")->daddr)
-		    ? # kernel >= 2.6.11
-		      @cast(sock, "inet_sock", "kernel")->daddr
-		    : @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->daddr)))
+	return @choose_defined(@cast(sock, "inet_sock")->sk->__sk_common->skc_daddr, # kernel >= 2.6.38
+		@choose_defined(@cast(sock, "inet_sock")->inet_daddr, # kernel >= 2.6.33
+		    @choose_defined(@cast(sock, "inet_sock")->daddr, # kernel >= 2.6.11
+			@cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->daddr)))
     }
 %( CONFIG_IPV6 == "[ym]" %?
     else if (family == %{ /* pure */ /* unprivileged */ AF_INET6 %}) {
diff --git a/tapset/linux/ipmib.stp b/tapset/linux/ipmib.stp
index 1ccb3bfd0..7de3ef1fd 100644
--- a/tapset/linux/ipmib.stp
+++ b/tapset/linux/ipmib.stp
@@ -335,7 +335,7 @@ probe ipmib.ForwDatagrams=kernel.function("ip_forward_finish")
 probe ipmib.OutRequests=kernel.function("ip_output"),
 			kernel.function("ip_mc_output")
 {
-	skb = @defined($skb) ? $skb : kernel_pointer($pskb);
+	skb = @choose_defined($skb, kernel_pointer($pskb));
 	op = 1;
 	SourceIsLocal = 1;
 	key = ipmib_filter_key(skb,op,SourceIsLocal);
@@ -429,20 +429,14 @@ function _rtn_unspec:long ()
 
 function _input_route_type:long (skb:long)
 {
-	rt = (@defined(@cast(skb, "sk_buff")->_skb_dst)
-	      ? @cast(skb, "sk_buff")->_skb_dst
-	      : (@defined(@cast(skb, "sk_buff")->rtable)
-	         ? @cast(skb, "sk_buff")->rtable
-		 : 0))
+	rt = @choose_defined(@cast(skb, "sk_buff")->_skb_dst,
+		@choose_defined(@cast(skb, "sk_buff")->rtable, 0))
 	return rt ? @cast(rt, "rtable")->rt_type : _rtn_unspec()
 }
 
 function _output_route_type:long (skb:long)
 {
-	rt = (@defined(@cast(skb, "sk_buff")->_skb_dst)
-	      ? @cast(skb, "sk_buff")->_skb_dst
-	      : (@defined(@cast(skb, "sk_buff")->dst)
-	         ? @cast(skb, "sk_buff")->dst
-		 : 0))
+	rt = @choose_defined(@cast(skb, "sk_buff")->_skb_dst,
+		@choose_defined(@cast(skb, "sk_buff")->dst, 0))
 	return rt ? @cast(rt, "rtable")->rt_type : _rtn_unspec()
 }
diff --git a/tapset/linux/irq.stp b/tapset/linux/irq.stp
index 3f13cf406..984325328 100644
--- a/tapset/linux/irq.stp
+++ b/tapset/linux/irq.stp
@@ -136,11 +136,11 @@ probe softirq.entry = kernel.trace("irq_softirq_entry") !,
      		      kernel.trace("softirq_entry") ?
 {
 	# kernels < 2.6.37
-	h = (@defined($h) ? $h : 0)
-	vec = (@defined($vec) ? $vec : 0)
+	h = @choose_defined($h, 0)
+	vec = @choose_defined($vec, 0)
 	action = (@defined($h) ? @cast($h,"softirq_action","kernel<linux/interrupt.h>")->action : 0)
 	# kernels >= 2.6.37
-	vec_nr = (@defined($vec_nr) ? $vec_nr : 0)
+	vec_nr = @choose_defined($vec_nr, 0)
 }
 
 /**
@@ -154,9 +154,9 @@ probe softirq.exit = kernel.trace("irq_softirq_exit") !,
 		     kernel.trace("softirq_exit") ?
 {
 	# kernels < 2.6.37
-	h = (@defined($h) ? $h : 0)
-	vec = (@defined($vec) ? $vec : 0)
+	h = @choose_defined($h, 0)
+	vec = @choose_defined($vec, 0)
 	action = (@defined($h) ? @cast($h,"softirq_action","kernel<linux/interrupt.h>")->action : 0)
 	# kernels >= 2.6.37
-	vec_nr = (@defined($vec_nr) ? $vec_nr : 0)
+	vec_nr = @choose_defined($vec_nr, 0)
 }
diff --git a/tapset/linux/linuxmib.stp b/tapset/linux/linuxmib.stp
index eabc8e7e8..8f87da3bd 100644
--- a/tapset/linux/linuxmib.stp
+++ b/tapset/linux/linuxmib.stp
@@ -102,7 +102,7 @@ probe linuxmib.ListenDrops=kernel.function("tcp_v4_syn_recv_sock").return
  */
 probe linuxmib.TCPMemoryPressures=kernel.function("tcp_enter_memory_pressure")
 {
-	sk = (@defined($sk) ? $sk : 0)
+	sk = @choose_defined($sk, 0)
 	op = 1;
 	if ( $tcp_memory_pressure ) next
 	key = linuxmib_filter_key(sk,op);
diff --git a/tapset/linux/memory.stp b/tapset/linux/memory.stp
index 825430079..ad878da64 100644
--- a/tapset/linux/memory.stp
+++ b/tapset/linux/memory.stp
@@ -519,8 +519,8 @@ probe __vm.kmalloc_node.kp = kernel.function("kmalloc_node").return ?
 	# '$size' argument above).  Note that we can see the '$flags'
 	# argument on x86_64 f11 (2.6.29.4-167.fc11.x86_64).  So, the
 	# best we can do here is just use 0 when $flags isn't defined.
-	gfp_flags = (@defined($flags) ? $flags : 0)
-	gfp_flag_name = __gfp_flag_str(@defined($flags) ? $flags : 0)
+	gfp_flags = @choose_defined($flags, 0)
+	gfp_flag_name = __gfp_flag_str(@choose_defined($flags, 0))
 
 	ptr = $return
 }
@@ -610,7 +610,7 @@ probe __vm.kfree.kp = kernel.function("kfree").return
 {
 	call_site = 0
 	caller_function = "unknown"
-	ptr = (@defined($x) ? $x : $objp)
+	ptr = @choose_defined($x, $objp)
 }
 
 /**
@@ -636,7 +636,7 @@ probe __vm.kmem_cache_free.kp = kernel.function("kmem_cache_free").return
 {
 	call_site = 0
 	caller_function = "unknown"
-	ptr = (@defined($x) ? $x : $objp)
+	ptr = @choose_defined($x, $objp)
 }
 
 /**
diff --git a/tapset/linux/networking.stp b/tapset/linux/networking.stp
index cf78586ee..27f4c62ae 100644
--- a/tapset/linux/networking.stp
+++ b/tapset/linux/networking.stp
@@ -157,7 +157,7 @@ probe netdev.change_rx_flag
 	= kernel.function("dev_change_rx_flags") ?
 {
 	dev_name = (@defined($dev) ? get_netdev_name($dev) : "unknown")
-	flags = (@defined($flags) ? $flags : 0)
+	flags = @choose_defined($flags, 0)
 }
 
 /**
diff --git a/tapset/linux/nfs.stp b/tapset/linux/nfs.stp
index 87a25f8c9..f6ca2d71e 100644
--- a/tapset/linux/nfs.stp
+++ b/tapset/linux/nfs.stp
@@ -43,9 +43,7 @@ function __nfsi_ndirty:long (inode:long)
 {
     if (inode == 0)	
         return -1
-    return (@defined(@cast(NFS_I(inode), "nfs_inode", "kernel:nfs")->ndirty)
-	    ? @cast(NFS_I(inode), "nfs_inode", "kernel:nfs")->ndirty
-	    : -1)
+    return @choose_defined(@cast(NFS_I(inode), "nfs_inode", "kernel:nfs")->ndirty, -1)
 }
 
 /* Get rsize from struct inode */
@@ -137,9 +135,8 @@ function __p2sb_flag:long (page:long)
 function __file_inode:long (file:long)
 {
     dentry = file
-	? (@defined(@cast(file, "file", "kernel:nfs")->f_path->dentry)
-	   ? @cast(file, "file", "kernel:nfs")->f_path->dentry
-	   : @cast(file, "file", "kernel:nfs")->f_dentry)
+	? @choose_defined(@cast(file, "file", "kernel:nfs")->f_path->dentry,
+		@cast(file, "file", "kernel:nfs")->f_dentry)
 	: 0
     if (dentry == 0)
         return 0
@@ -165,9 +162,8 @@ function __file_mode:long (file:long)
 function __file_parentname:string (file:long)
 {
     dentry = file
-	? (@defined(@cast(file, "file", "kernel:nfs")->f_path->dentry)
-	   ? @cast(file, "file", "kernel:nfs")->f_path->dentry
-	   : @cast(file, "file", "kernel:nfs")->f_dentry)
+	? @choose_defined(@cast(file, "file", "kernel:nfs")->f_path->dentry,
+		@cast(file, "file", "kernel:nfs")->f_dentry)
 	: 0
     d_parent = dentry? @cast(dentry, "dentry", "kernel:nfs")->d_parent : 0
     if (d_parent == 0)
diff --git a/tapset/linux/nfs_proc.stp b/tapset/linux/nfs_proc.stp
index b84509265..19078b14f 100644
--- a/tapset/linux/nfs_proc.stp
+++ b/tapset/linux/nfs_proc.stp
@@ -59,9 +59,8 @@ function stap_NFS_CLIENT:long(inode:long)
 function NFS_PROTO:long(inode:long)
 {
     nfsserver = NFS_SERVER(inode)
-    return (@defined(@cast(nfsserver, "nfs_server", "kernel:nfs")->nfs_client)
-	    ? @cast(nfsserver, "nfs_server", "kernel:nfs")->nfs_client->rpc_ops
-	    : @cast(nfsserver, "nfs_server", "kernel:nfs")->rpc_ops)
+    return @choose_defined(@cast(nfsserver, "nfs_server", "kernel:nfs")->nfs_client->rpc_ops,
+	    @cast(nfsserver, "nfs_server", "kernel:nfs")->rpc_ops)
 }
 
 
@@ -929,7 +928,7 @@ probe nfs.proc2.write_setup = kernel.function("nfs_proc_write_setup") !,
 
         count = $data->args->count
         offset = $data->args->offset
-	how = (@defined($how) ? $how : $data->args->stable)
+	how = @choose_defined($how, $data->args->stable)
         bitmask0 = 0
         bitmask1 = 0
 
@@ -958,7 +957,7 @@ probe nfs.proc3.write_setup = kernel.function("nfs3_proc_write_setup") !,
 
         count = $data->args->count
         offset = $data->args->offset
-	how = (@defined($how) ? $how : $data->args->stable)
+	how = @choose_defined($how, $data->args->stable)
         bitmask0 = 0
         bitmask1 = 0
 
@@ -986,7 +985,7 @@ probe nfs.proc4.write_setup = kernel.function("nfs4_proc_write_setup") !,
 
         count = $data->args->count
         offset = $data->args->offset
-	how = (@defined($how) ? $how : $data->args->stable)
+	how = @choose_defined($how, $data->args->stable)
         bitmask0 = __nfsv4_bitmask($data->inode,0)
         bitmask1 = __nfsv4_bitmask($data->inode,1)
 	//timestamp = $jiffies
diff --git a/tapset/linux/nfsd.stp b/tapset/linux/nfsd.stp
index 3db2d70cf..579139ab5 100644
--- a/tapset/linux/nfsd.stp
+++ b/tapset/linux/nfsd.stp
@@ -348,7 +348,7 @@ probe nfsd.proc2.read = kernel.function("nfsd_proc_read") !,
 
 	count = $argp->count 
 	offset = $argp->offset 
-	vec = (@defined($rqstp->rq_vec) ? $rqstp->rq_vec : $argp->vec)
+	vec = @choose_defined($rqstp->rq_vec, $argp->vec)
 	vlen = $argp->vlen
 
 	name = "nfsd.proc2.read"
@@ -379,7 +379,7 @@ probe nfsd.proc3.read = kernel.function("nfsd3_proc_read") !,
 
 	count = $argp->count 
 	offset = $argp->offset 
-	vec = (@defined($rqstp->rq_vec) ? $rqstp->rq_vec : $argp->vec)
+	vec = @choose_defined($rqstp->rq_vec, $argp->vec)
 	vlen = $argp->vlen
 
 	name = "nfsd.proc3.read"
@@ -466,7 +466,7 @@ probe nfsd.proc2.write = kernel.function("nfsd_proc_write") !,
 
 	count = $argp->len
 	offset = $argp->offset 
-	vec = (@defined($rqstp->rq_vec) ? $rqstp->rq_vec : $argp->vec)
+	vec = @choose_defined($rqstp->rq_vec, $argp->vec)
 	vlen = $argp->vlen
 	stable = 1			# hardcoded in nfsd_proc_write()
 
@@ -500,7 +500,7 @@ probe nfsd.proc3.write = kernel.function("nfsd3_proc_write") !,
 
 	count = $argp->count 
 	offset = $argp->offset 
-	vec = (@defined($rqstp->rq_vec) ? $rqstp->rq_vec : $argp->vec)
+	vec = @choose_defined($rqstp->rq_vec, $argp->vec)
 	vlen = $argp->vlen
 	stable = $argp->stable
 
@@ -996,7 +996,7 @@ probe nfsd.open = kernel.function("nfsd_open") !,
 	client_ip = addr_from_rqst_str($rqstp)
 	fh = __svc_fh($fhp)
 
-	access = (@defined($access) ? $access : $may_flags)
+	access = @choose_defined($access, $may_flags)
 	type = $type
 
 	name = "nfsd.open"
@@ -1053,7 +1053,7 @@ probe nfsd.read = kernel.function("nfsd_read") !,
 	client_ip = addr_from_rqst_str($rqstp)
 	fh = __svc_fh($fhp)
 
-	file = (@defined($file) ? $file : 0)
+	file = @choose_defined($file, 0)
 	count = kernel_long($count)
 	offset = $offset
 	vec = $vec
@@ -1094,7 +1094,7 @@ probe nfsd.write = kernel.function("nfsd_write") !,
 	client_ip = addr_from_rqst_str($rqstp)
 	fh = __svc_fh($fhp)
 
-	file = (@defined($file) ? $file : 0)
+	file = @choose_defined($file, 0)
 %( kernel_v >= "2.6.30" %?
 	count = kernel_long($cnt)
 %:
diff --git a/tapset/linux/rpc.stp b/tapset/linux/rpc.stp
index d29b7bf8f..1aff639d3 100644
--- a/tapset/linux/rpc.stp
+++ b/tapset/linux/rpc.stp
@@ -172,8 +172,7 @@ probe _sunrpc.clnt.create_client.rpc_new_client_inline =
 		authflavor = $args->authflavor
 
 		prot = $xprt->prot
-		port = (@defined($xprt->port)
-			? $xprt->port : port_from_xprt($xprt))
+		port = @choose_defined($xprt->port, port_from_xprt($xprt))
 	}
 	else {				# kernel > 2.6.18 (with bad debuginfo)
 %(systemtap_v <= "1.7" %?
@@ -204,8 +203,7 @@ probe _sunrpc.clnt.create_client.rpc_new_client =
 	authflavor = $flavor
 
 	prot = $xprt->prot
-	port = (@defined($xprt->port)
-		? $xprt->port : port_from_xprt($xprt))
+	port = @choose_defined($xprt->port, port_from_xprt($xprt))
 }
 
 probe _sunrpc.clnt.create_client.rpc_create_client =
@@ -227,8 +225,7 @@ probe _sunrpc.clnt.create_client.rpc_create_client =
 	}
 
 	prot = $xprt->prot
-	port = (@defined($xprt->port)
-		? $xprt->port : port_from_xprt($xprt))
+	port = @choose_defined($xprt->port, port_from_xprt($xprt))
 }
 
 /*
@@ -441,16 +438,12 @@ probe sunrpc.clnt.call_sync = kernel.function("rpc_call_sync") !,
 	prot = prot_from_clnt($clnt)
 	port = port_from_clnt($clnt)
 	xid  = xid_from_clnt($clnt)
-	dead = (@defined($clnt->cl_dead) ? $clnt->cl_dead
-		: (@defined(&$clnt->cl_kref->refcount)
-		   ? (atomic_read(&$clnt->cl_kref->refcount) == 0)
-		   : (atomic_read(&$clnt->cl_count) == 0)))
+	dead = @choose_defined($clnt->cl_dead,
+		atomic_read(@choose_defined(&$clnt->cl_kref->refcount,
+					    &$clnt->cl_count)) == 0)
 
 	proc = proc_from_msg($msg)
-	procname = (@defined($msg->rpc_proc->p_name)
-		    ? ($msg->rpc_proc->p_name
-		       ? kernel_string($msg->rpc_proc->p_name) : "NULL")
-		    : "NULL")
+	procname = kernel_string2(@choose_defined($msg->rpc_proc->p_name, 0), "NULL")
 	flags = $flags
 	
 	name = "sunrpc.clnt.call_sync"
@@ -490,16 +483,12 @@ probe sunrpc.clnt.call_async = kernel.function("rpc_call_async") !,
 	prot = prot_from_clnt($clnt)
 	port = port_from_clnt($clnt)
 	xid  = xid_from_clnt($clnt)
-	dead = (@defined($clnt->cl_dead) ? $clnt->cl_dead
-		: (@defined(&$clnt->cl_kref->refcount)
-		   ? (atomic_read(&$clnt->cl_kref->refcount) == 0)
-		   : (atomic_read(&$clnt->cl_count) == 0)))
+	dead = @choose_defined($clnt->cl_dead,
+		atomic_read(@choose_defined(&$clnt->cl_kref->refcount,
+					    &$clnt->cl_count)) == 0)
 
 	proc = proc_from_msg($msg)
-	procname = (@defined($msg->rpc_proc->p_name)
-		    ? ($msg->rpc_proc->p_name
-		       ? kernel_string($msg->rpc_proc->p_name) : "NULL")
-		    : "NULL")
+	procname = kernel_string2(@choose_defined($msg->rpc_proc->p_name, 0), "NULL")
 	flags = $flags
 	
 	name = "sunrpc.clnt.call_async"
@@ -1043,20 +1032,16 @@ function prog_from_clnt:long(clnt:long)
 {
 	if (clnt == 0)
 		return 0
-	if (@defined(@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_prog))
-		return @cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_prog
-	else
-		return @cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_pmap->pm_prog
+	return @choose_defined(@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_prog,
+		@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_pmap->pm_prog)
 }
 
 function vers_from_clnt:long(clnt:long)
 {
 	if (clnt == 0)
 		return 0
-	if (@defined(@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_vers))
-		return @cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_vers
-	else
-		return @cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_pmap->pm_vers
+	return @choose_defined(@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_vers,
+		@cast(clnt, "rpc_clnt", "kernel:sunrpc")->cl_pmap->pm_vers)
 }
 
 function prot_from_clnt:long(clnt:long)
diff --git a/tapset/linux/scheduler.stp b/tapset/linux/scheduler.stp
index afce4eea7..7596a4670 100644
--- a/tapset/linux/scheduler.stp
+++ b/tapset/linux/scheduler.stp
@@ -297,8 +297,8 @@ probe __scheduler.migrate.kp =
 	kernel.function("set_task_cpu") !,
 	kernel.function("pull_task") ?
 {
-	cpu_to = (@defined($new_cpu) ? $new_cpu
-		  : @defined($cpu) ? $cpu : $this_cpu)
+	cpu_to = @choose_defined($new_cpu,
+                @choose_defined($cpu, $this_cpu))
 }
 probe __scheduler.migrate.tp = kernel.trace("sched_migrate_task")
 {
diff --git a/tapset/linux/scsi.stp b/tapset/linux/scsi.stp
index dafb70feb..b8f0c2cc2 100644
--- a/tapset/linux/scsi.stp
+++ b/tapset/linux/scsi.stp
@@ -64,7 +64,7 @@ probe scsi.ioentry.sr =
 
 probe scsi.ioentry = scsi.ioentry.* ?
 {
-        req_addr = @defined($req) ? $req : $rq;
+        req_addr = @choose_defined($req, $rq);
 	if(@cast(req_addr,"request")->rq_disk == 0)  {
 		disk_major = -1
 		disk_minor = -1
@@ -104,10 +104,10 @@ probe scsi.iodispatching
 	device_state_str = describe_device_state(device_state)
 	data_direction = $cmd->sc_data_direction
 	data_direction_str = describe_data_direction(data_direction)
-	request_buffer = (@defined($cmd->sdb->table->sgl)
-	    ? $cmd->sdb->table->sgl : $cmd->request_buffer)
-	request_bufflen = (@defined($cmd->sdb->length)
-	    ? $cmd->sdb->length : $cmd->request_bufflen)
+	request_buffer = @choose_defined($cmd->sdb->table->sgl,
+					 $cmd->request_buffer)
+	request_bufflen = @choose_defined($cmd->sdb->length,
+					  $cmd->request_bufflen)
 	req_addr = $cmd->request
 }
 
@@ -175,9 +175,8 @@ probe scsi.iocompleted
 
 function timer_pending:long(timer:long)
 {
-	return (@defined(@cast(timer, "timer_list")->entry->next)
-		? (@cast(timer, "timer_list")->entry->next != 0)
-		: (@cast(timer, "timer_list")->base != 0))
+	return (@choose_defined(@cast(timer, "timer_list")->entry->next,
+				@cast(timer, "timer_list")->base) != 0)
 }
 
 function scsi_timer_pending:long(cmd:long)
diff --git a/tapset/linux/signal.stp b/tapset/linux/signal.stp
index e9a5b94fc..f0cfbbc44 100644
--- a/tapset/linux/signal.stp
+++ b/tapset/linux/signal.stp
@@ -60,9 +60,9 @@ probe signal.send = __signal.send.send_sigqueue,
 probe __signal.send.send_sigqueue = kernel.function("send_sigqueue")
 {
     name = "send_sigqueue"
-    task = (@defined($t) ? $t : $p)
-    sig = (@defined($q->info->si_signo) ? $q->info->si_signo : $sig)
-    sinfo = (@defined($q->info) ? $q->info : 0)
+    task = @choose_defined($t, $p)
+    sig = @choose_defined($q->info->si_signo, $sig)
+    sinfo = @choose_defined($q->info, 0)
     shared = 0
     send2queue = 1
 }
@@ -609,7 +609,7 @@ probe signal.handle = kernel.function("handle_rt_signal64") ?,
     sinfo = $info
     sig_code = $info->si_code
     ka_addr = $ka
-    oldset_addr = (@defined($oldset) ? $oldset : $set)
+    oldset_addr = @choose_defined($oldset, $set)
     regs = $regs
 
     // Check whether the signal is a User Mode or Kernel mode Signal.
diff --git a/tapset/linux/socket.stp b/tapset/linux/socket.stp
index 080f9559c..fa0b18d63 100644
--- a/tapset/linux/socket.stp
+++ b/tapset/linux/socket.stp
@@ -208,7 +208,7 @@ probe socket.aio_write = kernel.function ("sock_aio_write")
 	name = "socket.aio_write"
 	_sock = _get_sock_addr ($iocb->ki_filp)
 	size = (@defined($iov) ? _get_sock_size ($iov, $nr_segs)
-		: @defined($count) ?$count : $size)
+		: @choose_defined($count, $size))
 	protocol = _sock_prot_num (_sock)
 	family = _sock_fam_num (_sock)
 	state = _sock_state_num (_sock)
@@ -275,7 +275,7 @@ probe socket.aio_read = kernel.function ("sock_aio_read")
 	name = "socket.aio_read"
 	_sock = _get_sock_addr ($iocb->ki_filp)
 	size = (@defined($iov) ? _get_sock_size ($iov, $nr_segs)
-		: @defined($count) ?$count : $size)
+		: @choose_defined($count, $size))
 	protocol = _sock_prot_num (_sock)
 	family = _sock_fam_num (_sock)
 	state = _sock_state_num (_sock)
diff --git a/tapset/linux/syscalls.stp b/tapset/linux/syscalls.stp
index 37f8629ad..121097c21 100644
--- a/tapset/linux/syscalls.stp
+++ b/tapset/linux/syscalls.stp
@@ -557,7 +557,7 @@ probe syscall.dup2 = kernel.function("sys_dup3").call !,
 {
 	oldfd = $oldfd
 	newfd = $newfd
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 
 	# Corner case handled by dup2
 	if ($oldfd == $newfd && flags == 0) next
@@ -574,7 +574,7 @@ probe syscall.dup2 = kernel.function("sys_dup3").call !,
 probe syscall.dup2.return = kernel.function("sys_dup3").return !,
                             kernel.function("sys_dup2").return
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 
 	# Corner case handled by dup2
 	if ($oldfd == $newfd && flags == 0) next
@@ -589,8 +589,8 @@ probe syscall.dup2.return = kernel.function("sys_dup3").return !,
 probe syscall.epoll_create = kernel.function("sys_epoll_create1").call !,
                              kernel.function("sys_epoll_create").call ?
 {
-	size = @defined($size) ? $size : 0;
-	flags = @defined($flags) ? $flags : 0;
+	size = @choose_defined($size, 0);
+	flags = @choose_defined($flags, 0);
 	if (flags == 0) {
 		name = "epoll_create";
 		argstr = sprint(size);
@@ -602,7 +602,7 @@ probe syscall.epoll_create = kernel.function("sys_epoll_create1").call !,
 probe syscall.epoll_create.return = kernel.function("sys_epoll_create1").return !,
                                     kernel.function("sys_epoll_create").return ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	name = (flags == 0) ? "epoll_create" : "epoll_create1";
 	retstr = return_str(1, $return)
 }
@@ -687,7 +687,7 @@ probe syscall.epoll_wait.return = kernel.function("compat_sys_epoll_wait").retur
 probe syscall.eventfd = kernel.function("sys_eventfd2").call !,
                         kernel.function("sys_eventfd").call ?
 {
-	flags = @defined($flags) ? $flags : 0
+	flags = @choose_defined($flags, 0)
 	if (flags == 0) {
 		name = "eventfd"
 		argstr = sprint($count)
@@ -699,7 +699,7 @@ probe syscall.eventfd = kernel.function("sys_eventfd2").call !,
 probe syscall.eventfd.return = kernel.function("sys_eventfd2").return !,
                                kernel.function("sys_eventfd").return ?
 {
-	flags = @defined($flags) ? $flags : 0
+	flags = @choose_defined($flags, 0)
 	name = flags == 0 ? "eventfd" : "eventfd2"
 	retstr = return_str(1, $return)
 }
@@ -716,7 +716,7 @@ probe syscall.execve = kernel.function("do_execve").call
 	name = "execve"
 	filename = kernel_string($filename)
 	# kernel 3.0 changed the pointer's name to __argv
-	__argv = @defined($__argv) ? $__argv : $argv
+	__argv = @choose_defined($__argv, $argv)
 	args = __get_argv(__argv, 0)
 	argstr = sprintf("%s %s", filename, __get_argv(__argv, 1))
 }
@@ -736,7 +736,7 @@ probe syscall.compat_execve = kernel.function("compat_do_execve").call ?
 	name = "compat_execve"
 	filename = kernel_string($filename)
 	# kernel 3.0 changed the pointer's name to __argv
-	__argv = @defined($__argv) ? $__argv : $argv
+	__argv = @choose_defined($__argv, $argv)
 	args = __get_compat_argv(__argv, 0)
 	argstr = sprintf("%s %s", filename, __get_compat_argv(__argv, 1))
 }
@@ -794,10 +794,10 @@ probe syscall.faccessat.return = kernel.function("sys_faccessat").return ?
 probe syscall.fadvise64 = kernel.function("sys_fadvise64").call ?
 {
 	name = "fadvise64"
-	fd = (@defined($fd) ? $fd : 0)
-	offset = (@defined($offset) ? $offset : 0)
-	len = (@defined($len) ? $len : 0)
-	advice = (@defined($advice) ? $advice : 0)
+	fd = @choose_defined($fd, 0)
+	offset = @choose_defined($offset, 0)
+	len = @choose_defined($len, 0)
+	advice = @choose_defined($advice, 0)
 	argstr = sprintf("%d, %d, %d, %s", $fd, $offset, $len, _fadvice_advice_str($advice))
 }
 probe syscall.fadvise64.return = kernel.function("sys_fadvise64").return ?
@@ -812,10 +812,10 @@ probe syscall.fadvise64.return = kernel.function("sys_fadvise64").return ?
 probe syscall.fadvise64_64 = kernel.function("sys_fadvise64_64").call ?
 {
 	name = "fadvise64_64"
-	fd = (@defined($fd) ? $fd : 0)
-	offset = (@defined($offset) ? $offset : 0)
-	len = (@defined($len) ? $len : 0)
-	advice = (@defined($advice) ? $advice : 0)
+	fd = @choose_defined($fd, 0)
+	offset = @choose_defined($offset, 0)
+	len = @choose_defined($len, 0)
+	advice = @choose_defined($advice, 0)
 	argstr = sprintf("%d, %d, %d, %s", $fd, $offset, $len, _fadvice_advice_str($advice))
 }
 probe syscall.fadvise64_64.return = kernel.function("sys_fadvise64_64").return ?
@@ -1620,12 +1620,12 @@ probe syscall.getresgid = kernel.function("sys_getresgid16").call ?,
                           kernel.function("sys_getresgid").call
 {
 	name = "getresgid"
-	rgid_uaddr = @defined($rgidp) ? $rgidp : $rgid
-	egid_uaddr = @defined($egidp) ? $egidp : $egid
-	sgid_uaddr = @defined($sgidp) ? $sgidp : $sgid
-	argstr = sprintf("%p, %p, %p", (@defined($rgidp) ? $rgidp : $rgid),
-			 (@defined($egidp) ? $egidp : $egid),
-			 (@defined($sgidp) ? $sgidp : $sgid))
+	rgid_uaddr = @choose_defined($rgidp, $rgid)
+	egid_uaddr = @choose_defined($egidp, $egid)
+	sgid_uaddr = @choose_defined($sgidp, $sgid)
+	argstr = sprintf("%p, %p, %p", @choose_defined($rgidp, $rgid),
+			 @choose_defined($egidp, $egid),
+			 @choose_defined($sgidp, $sgid))
 }
 probe syscall.getresgid.return = kernel.function("sys_getresgid16").return ?,
                                  kernel.function("sys_getresgid").return
@@ -1642,12 +1642,12 @@ probe syscall.getresuid = kernel.function("sys_getresuid16").call ?,
                           kernel.function("sys_getresuid").call
 {
 	name = "getresuid"
-	ruid_uaddr = @defined($ruidp) ? $ruidp : $ruid
-	euid_uaddr = @defined($euidp) ? $euidp : $euid
-	suid_uaddr = @defined($suidp) ? $suidp : $suid
-	argstr = sprintf("%p, %p, %p", (@defined($ruidp) ? $ruidp : $ruid),
-			 (@defined($euidp) ? $euidp : $euid),
-			 (@defined($suidp) ? $suidp : $suid))
+	ruid_uaddr = @choose_defined($ruidp, $ruid)
+	euid_uaddr = @choose_defined($euidp, $euid)
+	suid_uaddr = @choose_defined($suidp, $suid)
+	argstr = sprintf("%p, %p, %p", @choose_defined($ruidp, $ruid),
+			 @choose_defined($euidp, $euid),
+			 @choose_defined($suidp, $suid))
 }
 probe syscall.getresuid.return = kernel.function("sys_getresuid16").return ?,
                                  kernel.function("sys_getresuid").return
@@ -1821,7 +1821,7 @@ probe syscall.getuid.return = kernel.function("sys_getuid16").return ?,
 probe syscall.getxattr = kernel.function("sys_getxattr").call
 {
 	name = "getxattr"
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 # 'name2' should have been 'name_str'.  Deprecate the old name.
 %(systemtap_v <= "1.4" %?
 	name2 = user_string($name)
@@ -1830,7 +1830,7 @@ probe syscall.getxattr = kernel.function("sys_getxattr").call
 	value_uaddr = $value
 	size = $size
 	argstr = sprintf("%s, %s, %p, %d",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		user_string_quoted($name),
 		$value, $size)
 }
@@ -1868,10 +1868,10 @@ probe syscall.inotify_add_watch = kernel.function("sys_inotify_add_watch").call
 	name = "inotify_add_watch"
 	fd = $fd
 	mask = $mask
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%d, %s, %s", $fd,
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		_inotify_watch_mask_str($mask))
 }
 
@@ -1888,7 +1888,7 @@ probe syscall.inotify_add_watch.return = kernel.function("sys_inotify_add_watch"
 probe syscall.inotify_init = kernel.function("sys_inotify_init1").call !,
                              kernel.function("sys_inotify_init").call ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	if (flags == 0) {
 		name = "inotify_init"
 		argstr = ""
@@ -1900,7 +1900,7 @@ probe syscall.inotify_init = kernel.function("sys_inotify_init1").call !,
 probe syscall.inotify_init.return = kernel.function("sys_inotify_init1").return !,
                                     kernel.function("sys_inotify_init").return ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	name = (flags == 0) ? "inotify_init" : "inotify_init1"
 	retstr = return_str(1, $return)
 }
@@ -2228,7 +2228,7 @@ probe syscall.lchown16.return = kernel.function("sys_lchown16").return ?
 probe syscall.lgetxattr = kernel.function("sys_lgetxattr").call
 {
 	name = "lgetxattr"
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 # 'name2' should have been 'name_str'.  Deprecate the old name.
 %(systemtap_v <= "1.4" %?
 	name2 = user_string($name)
@@ -2237,7 +2237,7 @@ probe syscall.lgetxattr = kernel.function("sys_lgetxattr").call
 	value_uaddr = $value
 	size = $size
 	argstr = sprintf("%s, %s, %p, %d",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		user_string_quoted($name),
 		value_uaddr, size)
 }
@@ -2314,10 +2314,10 @@ probe syscall.listxattr = kernel.function("sys_listxattr").call
 	name = "listxattr"
 	list_uaddr = $list
 	size = $size
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %p, %d",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		$list, $size)
 }
 probe syscall.listxattr.return = kernel.function("sys_listxattr").return
@@ -2334,10 +2334,10 @@ probe syscall.llistxattr = kernel.function("sys_llistxattr").call
 	name = "llistxattr"
 	list_uaddr = $list
 	size = $size
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %p, %d",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		$list, $size)
 }
 probe syscall.llistxattr.return = kernel.function("sys_llistxattr").return
@@ -2399,10 +2399,10 @@ probe syscall.lremovexattr = kernel.function("sys_lremovexattr").call
 	name2 = user_string($name)
 %)
 	name_str = user_string($name)
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %s",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		user_string_quoted($name))
 }
 probe syscall.lremovexattr.return = kernel.function("sys_lremovexattr").return
@@ -2439,15 +2439,15 @@ probe syscall.lseek.return = kernel.function("sys_lseek").return
 probe syscall.lsetxattr = kernel.function("sys_lsetxattr").call
 {
 	name = "lsetxattr"
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	name_uaddr = $name
 	name_str = user_string($name)
 	value_uaddr = $value
 	size = $size
 	flags = $flags
 	argstr = sprintf("%s, %s, %p, %d, %d",
-			user_string_quoted(@defined($pathname) ? $pathname : $path),
+			user_string_quoted(@choose_defined($pathname, $path)),
 			user_string_quoted($name),
 			value_uaddr, $size, $flags)
 }
diff --git a/tapset/linux/syscalls2.stp b/tapset/linux/syscalls2.stp
index 63faae4ee..c12adadd2 100644
--- a/tapset/linux/syscalls2.stp
+++ b/tapset/linux/syscalls2.stp
@@ -407,9 +407,9 @@ probe syscall.poll = kernel.function("sys_poll").call
 	name = "poll"
 	ufds_uaddr = $ufds
 	nfds = $nfds
-	timeout = (@defined($timeout_msecs) ? $timeout_msecs : $timeout)
+	timeout = @choose_defined($timeout_msecs, $timeout)
 	argstr = sprintf("%p, %d, %d", $ufds, $nfds,
-		(@defined($timeout_msecs) ? $timeout_msecs : $timeout))
+		@choose_defined($timeout_msecs, $timeout))
 }
 probe syscall.poll.return = kernel.function("sys_poll").return
 {
@@ -759,9 +759,9 @@ probe syscall.readlinkat = kernel.function("sys_readlinkat").call ?
 	dfd = $dfd
 	buf_uaddr = $buf
 	bufsiz = $bufsiz
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %s, %p, %d", _dfd_str($dfd),
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		$buf, $bufsiz)
 }
 
@@ -974,7 +974,7 @@ probe syscall.remap_file_pages = kernel.function("sys_remap_file_pages").call ?
 	name = "remap_file_pages"
 	start = $start
 	size = $size
-	prot = (@defined($prot) ? $prot : $__prot)
+	prot = @choose_defined($prot, $__prot)
 	pgoff = $pgoff
 	flags = $flags
 	argstr = sprintf("%p, %p, %p, %p, %p", start, size, prot,
@@ -997,9 +997,9 @@ probe syscall.removexattr = kernel.function("sys_removexattr").call
 	name = "removexattr"
 	name_str = user_string($name)
 
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %s",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		user_string_quoted($name))
 }
 probe syscall.removexattr.return = kernel.function("sys_removexattr").return
@@ -1188,7 +1188,7 @@ probe syscall.rt_sigprocmask = kernel.function("sys32_rt_sigprocmask").call ?,
 	name = "rt_sigprocmask"
 	how  = $how
 	how_str = _sigprocmask_how_str($how)
-	set_uaddr    = @defined($set) ? $set : $nset
+	set_uaddr    = @choose_defined($set, $nset)
 	oldset_uaddr = $oset
 	argstr = sprintf("%s, [%s], %p, %d", how_str, _stp_sigset_u(set_uaddr),
 		$oset, $sigsetsize)
@@ -1392,7 +1392,7 @@ probe syscall.sched_setaffinity = kernel.function("sys_sched_setaffinity").call
 {
 	name = "sched_setaffinity"
 	pid = $pid
-	len = (@defined($len) ? $len : 0)
+	len = @choose_defined($len, 0)
 	mask_uaddr = $user_mask_ptr
 	argstr = sprintf("%d, %d, %p", $pid, $len, $user_mask_ptr)
 }
@@ -2225,15 +2225,15 @@ probe syscall.setuid.return = kernel.function("sys_setuid16").return ?,
 probe syscall.setxattr = kernel.function("sys_setxattr").call
 {
 	name = "setxattr"
-	path_uaddr = (@defined($pathname) ? $pathname : $path)
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path_uaddr = @choose_defined($pathname, $path)
+	path = user_string(@choose_defined($pathname, $path))
 	name_uaddr = $name
 	name_str = user_string($name)
 	value_uaddr = $value
 	size = $size
 	flags = $flags
 	argstr = sprintf("%s, %s, %p, %d, %d",
-			user_string_quoted(@defined($pathname) ? $pathname : $path),
+			user_string_quoted(@choose_defined($pathname, $path)),
 			user_string_quoted($name),
 			value_uaddr, $size, $flags)
 }
@@ -2447,7 +2447,7 @@ probe syscall.signal.return = kernel.function("sys_signal").return ?
 probe syscall.signalfd = kernel.function("sys_signalfd4").call !,
                          kernel.function("sys_signalfd").call ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	if (flags == 0) {
 		name = "signalfd"
 		argstr = sprintf("%d, %p, %d", $ufd, $user_mask, $sizemask)
@@ -2460,14 +2460,14 @@ probe syscall.signalfd = kernel.function("sys_signalfd4").call !,
 probe syscall.signalfd.return = kernel.function("sys_signalfd4").return !,
                                 kernel.function("sys_signalfd").return ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	name = (flags == 0) ? "signalfd" : "signalfd4"
 	retstr = return_str(1, $return)
 }
 probe syscall.compat_signalfd = kernel.function("compat_sys_signalfd4").call !,
                                 kernel.function("compat_sys_signalfd").call ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	if (flags == 0) {
 		name = "compat_signalfd"
 		argstr = sprintf("%d, %p, %d", $ufd, $sigmask, $sigsetsize)
@@ -2481,7 +2481,7 @@ probe syscall.compat_signalfd.return =
 		kernel.function("compat_sys_signalfd4").return !,
 		kernel.function("compat_sys_signalfd").return ?
 {
-	flags = @defined($flags) ? $flags : 0;
+	flags = @choose_defined($flags, 0);
 	name = (flags == 0) ? "compat_signalfd" : "compat_signalfd4"
 	retstr = return_str(1, $return)
 }
@@ -2512,7 +2512,7 @@ probe syscall.sigprocmask = kernel.function("sys_sigprocmask").call ?,
 	name = "sigprocmask"
 	how  = $how
 	how_str = _sigprocmask_how_str($how)
-	set_uaddr    = @defined($set) ? $set : $nset
+	set_uaddr    = @choose_defined($set, $nset)
 	oldset_uaddr = $oset
 	argstr = sprintf("%s, %p, %p", how_str, set_uaddr, $oset)
 }
@@ -2688,9 +2688,9 @@ probe syscall.statfs = kernel.function("compat_sys_statfs").call ?,
 {
 	name = "statfs"
 	buf_uaddr = $buf
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %p",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		$buf)
 }
 
@@ -2713,9 +2713,9 @@ probe syscall.statfs64 = kernel.function("compat_sys_statfs64").call ?,
 	sz = $sz
 	buf_uaddr = $buf
 
-	path = user_string(@defined($pathname) ? $pathname : $path)
+	path = user_string(@choose_defined($pathname, $path))
 	argstr = sprintf("%s, %d, %p",
-		user_string_quoted(@defined($pathname) ? $pathname : $path),
+		user_string_quoted(@choose_defined($pathname, $path)),
 		$sz, $buf)
 }
 
@@ -3313,8 +3313,8 @@ probe syscall.ustat32 = kernel.function("compat_sys_ustat").call ?,
 {
 	name = "ustat"
 	dev = $dev
-	ubuf_uaddr = (@defined($u) ? $u : $u32p)
-	argstr = sprintf("%d, %p", $dev, (@defined($u) ? $u : $u32p))
+	ubuf_uaddr = @choose_defined($u, $u32p)
+	argstr = sprintf("%d, %p", $dev, @choose_defined($u, $u32p))
 }
 
 probe syscall.ustat.return = kernel.function("sys_ustat").return ?,
@@ -3479,13 +3479,13 @@ probe syscall.compat_vmsplice.return = kernel.function("compat_sys_vmsplice").re
 probe syscall.wait4 = kernel.function("sys_wait4").call
 {
 	name = "wait4"
-	pid = (@defined($upid) ? $upid : $pid)
+	pid = @choose_defined($upid, $pid)
 	status_uaddr = $stat_addr
 	options = $options & 0xffffffff
 	options_str = _wait4_opt_str(options)
 	rusage_uaddr = $ru
 	argstr = sprintf("%d, %p, %s, %p",
-		(@defined($upid) ? $upid : $pid),
+		@choose_defined($upid, $pid),
 		$stat_addr, options_str, $ru)
 }
 probe syscall.wait4.return = kernel.function("sys_wait4").return
@@ -3512,7 +3512,7 @@ probe syscall.wait4.return = kernel.function("sys_wait4").return
 probe syscall.waitid = kernel.function("sys_waitid").call
 {
 	name = "waitid"
-	pid = (@defined($upid) ? $upid : $pid)
+	pid = @choose_defined($upid, $pid)
 	which = $which
 	which_str = _waitid_which_str($which)
 	infop_uaddr = $infop
@@ -3520,7 +3520,7 @@ probe syscall.waitid = kernel.function("sys_waitid").call
 	options_str = _waitid_opt_str($options)
 	rusage_uaddr = $ru
 	argstr = sprintf("%d, %d, %p, %s, %p", $which,
-		(@defined($upid) ? $upid : $pid), $infop,
+		@choose_defined($upid, $pid), $infop,
 		_waitid_opt_str($options), $ru)
 }
 probe syscall.waitid.return = kernel.function("sys_waitid").return
diff --git a/tapset/linux/task.stp b/tapset/linux/task.stp
index 8322a83eb..df4a44a73 100644
--- a/tapset/linux/task.stp
+++ b/tapset/linux/task.stp
@@ -40,10 +40,9 @@ function task_current:long () %{ /* pure */
  */
 function task_parent:long(task:long)
 {
-    return (@defined(@cast(task, "task_struct",
-			   "kernel<linux/sched.h>")->real_parent)
-	    ? @cast(task, "task_struct", "kernel<linux/sched.h>")->real_parent
-	    : @cast(task, "task_struct", "kernel<linux/sched.h>")->parent)
+    return @choose_defined(
+	    @cast(task, "task_struct", "kernel<linux/sched.h>")->real_parent,
+	    @cast(task, "task_struct", "kernel<linux/sched.h>")->parent)
 }
 
 /**
@@ -256,9 +255,8 @@ function task_nice:long (task:long) %{ /* pure */
  */
 function task_cpu:long (task:long)
 {
-    ti = (@defined(@cast(task, "task_struct", "kernel<linux/sched.h>")->stack)
-	  ? @cast(task, "task_struct", "kernel<linux/sched.h>")->stack
-	  : @cast(task, "task_struct", "kernel<linux/sched.h>")->thread_info);
+    ti = @choose_defined(@cast(task, "task_struct", "kernel<linux/sched.h>")->stack,
+	  @cast(task, "task_struct", "kernel<linux/sched.h>")->thread_info);
     return @cast(ti, "thread_info", "kernel<linux/sched.h>")->cpu
 }
 
diff --git a/tapset/linux/tcp.stp b/tapset/linux/tcp.stp
index cf9b4f55a..7737a2c3f 100644
--- a/tapset/linux/tcp.stp
+++ b/tapset/linux/tcp.stp
@@ -77,11 +77,9 @@ function tcp_ts_get_info_state:long(sock:long)
 /* return the TCP destination port for a given sock */
 function __tcp_sock_dport:long (sock:long)
 {
-    return (@defined(@cast(sock, "inet_sock")->inet_dport)
-	    ? @cast(sock, "inet_sock")->inet_dport # kernel >= 2.6.33
-	    : (@defined(@cast(sock, "inet_sock")->dport)
-	       ? @cast(sock, "inet_sock", "kernel")->dport # kernel >= 2.6.11
-	       : @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->dport))
+    return @choose_defined(@cast(sock, "inet_sock")->inet_dport, # kernel >= 2.6.33
+	    @choose_defined(@cast(sock, "inet_sock", "kernel")->dport, # kernel >= 2.6.11
+		@cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->dport))
 }
 
 /* returns the TCP header for recent (<2.6.21) kernel */
@@ -159,11 +157,9 @@ function __tcp_skb_dport:long (tcphdr:long){
 /* return the TCP source port for a given sock */
 function __tcp_sock_sport:long (sock:long)
 {
-    return (@defined(@cast(sock, "inet_sock")->inet_sport)
-	    ? @cast(sock, "inet_sock")->inet_sport # kernel >= 2.6.33
-	    : (@defined(@cast(sock, "inet_sock")->sport)
-	       ? @cast(sock, "inet_sock", "kernel")->sport # kernel >= 2.6.11
-	       : @cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->sport))
+    return @choose_defined(@cast(sock, "inet_sock")->inet_sport, # kernel >= 2.6.33
+	    @choose_defined(@cast(sock, "inet_sock", "kernel")->sport, # kernel >= 2.6.11
+		@cast(sock, "inet_sock", "kernel<net/ip.h>")->inet->sport))
 }
 
 global sockstate[13], sockstate_init_p
@@ -686,7 +682,7 @@ probe tcp.ipv6.receive = kernel.function("tcp_v6_rcv")!,
 	module("ipv6").function("tcp_v6_rcv")
 {
 	name = "tcp.ipv6.receive"
-	iphdr = __get_skb_iphdr(@defined($skb) ? $skb : kernel_pointer($pskb))
+	iphdr = __get_skb_iphdr(@choose_defined($skb, kernel_pointer($pskb)))
 	# If we're here, by definition we're doing AF_INET6, not AF_INET.
 	family = %{ /* pure */ AF_INET6 %}
 	saddr = format_ipaddr(&@cast(iphdr, "ipv6hdr")->saddr,
@@ -699,7 +695,7 @@ probe tcp.ipv6.receive = kernel.function("tcp_v6_rcv")!,
 	# Procol ID (ETH_P_*), not an IP protocol ID (IPPROTO_*).
 	protocol = %{ /* pure */ IPPROTO_TCP %}
 
-	tcphdr = __get_skb_tcphdr(@defined($skb) ? $skb : kernel_pointer($pskb))
+	tcphdr = __get_skb_tcphdr(@choose_defined($skb, kernel_pointer($pskb)))
 	dport = __tcp_skb_dport(tcphdr)
 	sport = __tcp_skb_sport(tcphdr)
 	urg = __tcp_skb_urg(tcphdr)
diff --git a/tapset/linux/tcpmib.stp b/tapset/linux/tcpmib.stp
index dfc94c3af..dc2a639dc 100644
--- a/tapset/linux/tcpmib.stp
+++ b/tapset/linux/tcpmib.stp
@@ -296,7 +296,7 @@ function _tcpmib_input_route_type:long (skb:long)
 probe
 __tcpmib.OutRsts.tcp_v4_send_reset = kernel.function("tcp_v4_send_reset")
 {
-        sk = (@defined($sk) ? $sk : 0)
+        sk = @choose_defined($sk, 0)
         op = 1;
         if ( _is_reset($skb) ) next
         if (_tcpmib_input_route_type($skb) != _rtn_local() )
diff --git a/tapset/linux/tty.stp b/tapset/linux/tty.stp
index 1f67fc03e..582d23814 100644
--- a/tapset/linux/tty.stp
+++ b/tapset/linux/tty.stp
@@ -24,8 +24,8 @@ probe tty.open = kernel.function("tty_open")
 	inode_state = $inode->i_state
 	inode_flags = $inode->i_flags
 
-	file_name = d_name(@defined($filp->f_path->dentry)
-		? $filp->f_path->dentry : $filp->f_dentry)
+	file_name = d_name(@choose_defined($filp->f_path->dentry,
+					   $filp->f_dentry))
 	file_mode = $filp->f_mode
 	file_flags = $filp->f_flags
 }
@@ -55,8 +55,8 @@ probe tty.release = kernel.function("tty_release")
 		inode_flags = -1
 	}
 
-	file_name = d_name(@defined($filp->f_path->dentry)
-		? $filp->f_path->dentry : $filp->f_dentry)
+	file_name = d_name(@choose_defined($filp->f_path->dentry,
+					   $filp->f_dentry))
 	file_mode = $filp->f_mode
 	file_flags = $filp->f_flags
 }
@@ -103,8 +103,8 @@ probe tty.resize = kernel.function("tiocswinsz")
  */
 probe tty.ioctl = kernel.function("tty_ioctl")
 {
-	name = kernel_string(@defined($file->f_path->dentry->d_iname)
-		? $file->f_path->dentry->d_iname : $file->f_dentry->d_iname)
+	name = kernel_string(@choose_defined($file->f_path->dentry->d_iname,
+					     $file->f_dentry->d_iname))
 	cmd = $cmd
 	arg = $arg
 }
@@ -160,8 +160,8 @@ probe tty.unregister = kernel.function("tty_unregister_device")
  */
 probe tty.poll = kernel.function("tty_poll")
 {
-	file_name = d_name(@defined($filp->f_path->dentry)
-		? $filp->f_path->dentry : $filp->f_dentry)
+	file_name = d_name(@choose_defined($filp->f_path->dentry,
+					   $filp->f_dentry))
 
 	wait_key = (@defined($wait->key) ? ($wait ? $wait->key : 0) : 0)
 }
@@ -201,8 +201,8 @@ probe tty.write = kernel.function("n_tty_write") !,
 	buffer = kernel_string($buf)
 	nr = $nr
 
-	file_name = d_name(@defined($file->f_path->dentry)
-		? $file->f_path->dentry : $file->f_dentry)
+	file_name = d_name(@choose_defined($file->f_path->dentry,
+					   $file->f_dentry))
 	driver_name = kernel_string($tty->driver->driver_name)
 }
 
@@ -218,7 +218,7 @@ probe tty.read = kernel.function("n_tty_read") !,
 {
 	buffer = kernel_string($buf)
 	nr = $nr
-	file_name = d_name(@defined($file->f_path->dentry)
-		? $file->f_path->dentry : $file->f_dentry)
+	file_name = d_name(@choose_defined($file->f_path->dentry,
+					   $file->f_dentry))
 	driver_name = kernel_string($tty->driver->driver_name)
 }
diff --git a/tapset/linux/vfs.stp b/tapset/linux/vfs.stp
index 6ca330190..f2cbc9291 100644
--- a/tapset/linux/vfs.stp
+++ b/tapset/linux/vfs.stp
@@ -105,9 +105,8 @@ function __file_maxbytes:long (file:long)
 function __file_filename:string (file:long)
 {
 	dentry = file
-		? (@defined(@cast(file, "file", "kernel")->f_path->dentry)
-			? @cast(file, "file", "kernel")->f_path->dentry
-			: @cast(file, "file", "kernel")->f_dentry)
+		? @choose_defined(@cast(file, "file", "kernel")->f_path->dentry,
+				  @cast(file, "file", "kernel")->f_dentry)
 		: 0
 	name = dentry? @cast(dentry, "dentry", "kernel")->d_name->name : 0
 	if (name == 0)
@@ -174,7 +173,7 @@ probe generic.fop.aio_read =
 	devname = __find_bdevname(dev, __file_bdev($iocb->ki_filp))
 	ino = __file_ino($iocb->ki_filp)
         
-	pos = (@defined($pos) ? $pos : kernel_pointer($ppos))
+	pos = @choose_defined($pos, kernel_pointer($ppos))
 	buf = $iov->iov_base
 	count = __iov_length($iov,$nr_segs,1,1) /*FIX ME: should be VERIFY_WRITE instead of 1*/
 	name = "generic_file_aio_read"
@@ -215,7 +214,7 @@ probe generic.fop.aio_write = kernel.function("generic_file_aio_write")
         count = (@defined($iov)
 		? __iov_length($iov,$nr_segs,1,0) /*FIX ME: should be VERIFY_READ instead of 0*/
 		: $count)
-	buf = (@defined($iov->iov_base) ? $iov->iov_base : $buf)
+	buf = @choose_defined($iov->iov_base, $buf)
 	name = "generic_file_aio_write"
 	argstr = sprintf("%d, %d, %p", count, pos, buf)
 
@@ -988,7 +987,7 @@ probe _vfs.block_prepare_write.return =
 
 probe _vfs.block_write_begin = kernel.function("block_write_begin") ?
 {
-	file = (@defined($file) ? $file : 0)
+	file = @choose_defined($file, 0)
 	pos = $pos
 	len = $len
 	flags = $flags
@@ -1005,7 +1004,7 @@ probe _vfs.block_write_begin.return =
 	name = "_vfs.block_write_begin"
 	retstr = sprintf("%d", $return)
 
-	file = (@defined($file) ? $file : 0)
+	file = @choose_defined($file, 0)
 	pos = $pos
 	len = $len
 	flags = $flags
diff --git a/tapset/linux/x86_64/syscalls.stp b/tapset/linux/x86_64/syscalls.stp
index ddc24ea7f..4cd741f9f 100644
--- a/tapset/linux/x86_64/syscalls.stp
+++ b/tapset/linux/x86_64/syscalls.stp
@@ -26,7 +26,7 @@ probe syscall.arch_prctl.return = kernel.function("sys_arch_prctl").return
 probe syscall.iopl = kernel.function("sys_iopl")
 {
 	name = "iopl"
-	level = (@defined($level) ? $level : $new_iopl)
+	level = @choose_defined($level, $new_iopl)
 	argstr = sprint(level)
 }
 probe syscall.iopl.return = kernel.function("sys_iopl").return
-- 
2.43.5