[PATCH] initscript: automatically detect uprobes dependency

[Stefan Hajnoczi <stefanha at redhat dot com>]

systemtap-initscript scripts that rely on uprobes must be configured
with the --save-uprobes option.  This option saves the generated
uprobes.ko module and loads it when running the script.

The uprobes dependency information is actually available at compile time
so we can autodetect as follows:
1. Check if uprobes.ko was generated during compile
2. When uprobes.ko was generated, touch <name>.uprobes in the cache
   directory.
3. Add the staprun -u option if <name>.uprobes exists

It is no longer necessary to specify the --save-uprobes option in the
initscript configuration file, although doing so allowed.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 initscript/systemtap.in | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/initscript/systemtap.in b/initscript/systemtap.in
index 683734d..c8219cb 100755
--- a/initscript/systemtap.in
+++ b/initscript/systemtap.in
@@ -495,13 +495,16 @@ compile_script () { # script checkcache
     return 1
   fi
   pushd "$tmpdir" &> /dev/null
-  logex $STAP -m "$1" -p4 -r $KRELEASE $opts "$f"
+  logex $STAP -m "$1" -p4 -r $KRELEASE --save-uprobes $opts "$f"
   ret=$?
   if [ $ret -eq 0 ]; then
     if [ -f "uprobes/uprobes.ko" ]; then
+      logex touch "$CACHE_PATH/$1.uprobes"
       logex mkdir -p "$CACHE_PATH/uprobes"
       logex mv "uprobes/uprobes.ko" "$CACHE_PATH/uprobes/"
       ret=$?
+    elif [ -f "$CACHE_PATH/$1.uprobes" ]; then
+      rm "$CACHE_PATH/$1.uprobes"
     fi
   fi
   if [ $ret -eq 0 ]; then
@@ -575,6 +578,10 @@ start_script () { # script
   mode=$?
   [ $mode -eq 0 ] && return 2
 
+  if [ -f "$CACHE_PATH/$s.uprobes" ]; then
+    opts="$opts -u$CACHE_PATH/uprobes/uprobes.ko"
+  fi
+
   clog " Starting $1 ... " -n
   tmpdir=`mktemp -d -p "$TEMP_PATH" cache.XXXXXXXX`  # bz7097
   if [ $? -ne 0 ]; then
@@ -767,7 +774,7 @@ compile () {
     return 1
   fi
   for s in $SCRIPTS; do
-    ss="$ss "`ls "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts" 2> /dev/null`
+    ss="$ss "`ls "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts" "$CACHE_PATH/$s.uprobes" 2> /dev/null`
   done
   ss=`echo -n $ss`
   if [ "$ss" ]; then
@@ -960,7 +967,7 @@ cleanup () {
   fi
 
   for s in $SCRIPTS; do
-    ss="$ss "`ls "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts" 2> /dev/null`
+    ss="$ss "`ls "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts" "$CACHE_PATH/$s.uprobes" 2> /dev/null`
   done
   ss=`echo -n $ss`
   if [ "$ss" ]; then
@@ -968,7 +975,7 @@ cleanup () {
     ask_yesno "Do you really want to remove above caches"
     [ $? -eq 0 ] && return 0
     for s in $SCRIPTS; do
-      logex rm -f "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts"
+      logex rm -f "$CACHE_PATH/$s.ko" "$CACHE_PATH/$s.opts" "$CACHE_PATH/$s.uprobes"
       [ $? -ne 0 ] && might_fail $"failed to clean cache $s.ko"
     done
     might_success "done"
-- 
1.9.3