tools/bootconfig: Fix tracing script filters and histogram dependencies

Hi Masami,

Thanks for the reviews and for picking up the previous fixes. Here are five more script fixes, based on bootconfig/core as you suggested.

They address:
- The documented ftrace.notraces setting being ignored by bconf2ftrace.sh.
- Single quotes in event actions producing invalid exported bootconfig.
- Literal filter text being mistaken for histogram variable syntax.
- Valid histogram dependency chains exceeding the exporter's retry limit.
- Helper key lookups matching unrelated bootconfig keys.

The action-quoting patch follows up on the trigger-filter fix you picked up. It uses the same warning approach for unrepresentable values that you suggested for event filters. The histogram scan uses POSIX sed.

I tested the conversion and export fixes in temporary tracefs instances on my Ubuntu machine, running kernel 7.0.0-38-generic, with recording disabled. The tests cover each relevant step and the combined series. The helper fix has focused checks, and all 81 combined fixture checks also pass with POSIX sed.

Feedback is welcome.

Thanks,
Eduardo

Eduardo Mucelli Rezende Oliveira (5):
tools/bootconfig: Read the documented ftrace.notraces key tools/bootconfig: Preserve quotes in exported event actions tools/bootconfig: Ignore filter strings when resolving histogram
variables
tools/bootconfig: Resolve histogram dependencies until no progress is
made
tools/bootconfig: Match literal keys in tracing script helpers

 tools/bootconfig/scripts/bconf2ftrace.sh |  2 +-
 tools/bootconfig/scripts/ftrace2bconf.sh | 27 ++++++++++++++++++------
 tools/bootconfig/scripts/xbc.sh          | 13 ++++++++----
 3 files changed, 31 insertions(+), 11 deletions(-)

base-commit: a52ceed51e9bf8f1ca9c2c868b14bf6861986c65

2.53.0

The boot-time tracing documentation and trace_boot_set_ftrace_filter() use ftrace.notraces for function exclusions. bconf2ftrace.sh instead looks up ftrace.notrace, so the documented option produces no writes to set_ftrace_notrace. This affects both the root instance and named ones.

Read the documented key so that the script applies the same exclusions as the in-kernel bootconfig consumer.

---
I tested the documented ftrace.notraces setting with one and two function names in a temporary tracefs instance on my Ubuntu machine, running kernel 7.0.0-38-generic, with recording disabled. The original script installed neither exclusion; the fixed script installed both exactly. Fixture checks also cover the root instance, named instances, arrays, an absent setting and the unchanged positive-filter path.

 tools/bootconfig/scripts/bconf2ftrace.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 7745c97e7abd..e5a833171b57 100755
@@ -258,7 +258,7 @@ setup_instance() { # [instance]
 	set_value_of ${instance}.tracer ${instancedir}/current_tracer
 	set_array_of ${instance}.ftrace.filters \
 		${instancedir}/set_ftrace_filter
-	set_array_of ${instance}.ftrace.notrace \
+	set_array_of ${instance}.ftrace.notraces \
 		${instancedir}/set_ftrace_notrace
 
 	if xbc_has_key ${instance}.alloc_snapshot; then

2.53.0

Reading complete trigger lines preserves filters that can contain single quotes. Enclosing every action in single bootconfig quotes then produces invalid output for a valid trigger such as traceoff if prev_comm == 'abc'.

Use double quotes for actions containing only single quotes. Actions with both quote types can be emitted without enclosing quotes when they have no bootconfig delimiters. Warn and skip unrepresentable actions containing both quote types and delimiters, following the event-filter handling.

---
I reproduced this with valid traceoff triggers using single-quoted filters in a temporary tracefs instance on my Ubuntu machine, running kernel 7.0.0-38-generic, with recording disabled.

The original export failed bootconfig parsing. With the fix, supported single-quoted actions parsed and their decoded commands could be restored unchanged to tracefs. Unrepresentable mixed-quote actions produced a warning and were skipped. Mixed quotes without delimiters and ordinary double-quoted filters were checked as well.

 tools/bootconfig/scripts/ftrace2bconf.sh | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

index 31702be0c68d..77ec17c94a17 100755
@@ -126,7 +126,22 @@ per_event_options() { # event-dir
 		*:count=*)
 			action="${action_cmd%:count=*}:${action_cmd##*:count=}$action_rest";;
 		esac
-		emit_kv $PREFIX.event.$group.$event.actions += "'$action'"
+		case "$action" in
+		*\'*)
+			case "$action" in
+			*\"*)
+				case "$action" in
+				*[,\;\#\}]*)
+					cat 1>&2 << EOF
+# WARN: $PREFIX.event.$group.$event.actions cannot be quoted for bootconfig. Skip it.
+EOF
+					continue;;
+				esac;;
+			*) action="\"$action\"";;
+			esac;;
+		*) action="'$action'";;
+		esac
+		emit_kv $PREFIX.event.$group.$event.actions += "$action"
 	done
 
 	if [ $GROUP_ENABLED -eq 0 ] && event_is_enabled $evdir/enable; then

2.53.0

The histogram variable resolver scans the entire trigger line, including its filter. A literal string such as "$not_a_variable" is consequently read as a variable reference and the histogram is deferred and omitted. Conversely, a filter containing ":dep0=" looks like a definition and can cause a consumer to be exported before its real provider.

Remove the filter portion before looking for variable definitions and references. Leave the complete filter intact when exporting the action.

---
I tested literal dollar signs and assignment-looking strings in histogram filters in a temporary tracefs instance on my Ubuntu machine, running kernel 7.0.0-38-generic, with recording disabled.

The original exporter omitted the dollar-sign cases and treated text inside another filter as a provider, putting a consumer first. With the fix, the literal filters were retained and the real provider was exported before its consumer.

 tools/bootconfig/scripts/ftrace2bconf.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 77ec17c94a17..8ba1a698611e 100755
@@ -86,10 +86,10 @@ synth_event_options() {
 # Variables resolver
 
 defined_vars() { # event-dir
-	grep "^hist" $1/trigger | grep -o ':[a-zA-Z0-9_]*='
+	grep "^hist" $1/trigger | sed 's/ if .*//' | grep -o ':[a-zA-Z0-9_]*='
 }
 referred_vars() {
-	grep "^hist" $1/trigger | grep -o '$[a-zA-Z0-9_]*'
+	grep "^hist" $1/trigger | sed 's/ if .*//' | grep -o '$[a-zA-Z0-9_]*'
 }
 
 event_is_enabled() { # enable-file

2.53.0

The exporter retries unresolved events only three times. A valid chain of eight histogram dependencies in reverse traversal order therefore exports only four histograms and reports the others as undefined, even though all their providers are present.

Retry while the unresolved event list changes. Stop when all events have been exported or a pass makes no progress, preserving the diagnostic for missing variables and dependency cycles.

---
I installed a valid chain of eight dependent histograms in a temporary tracefs instance on my Ubuntu machine, running kernel 7.0.0-38-generic, with recording disabled.

The original exporter emitted only four histograms, so replay restored half the configuration. With the fix, all eight were exported in provider order and restored correctly. Fixture checks cover shorter and longer chains, missing variables and cycles that must stop without looping.

 tools/bootconfig/scripts/ftrace2bconf.sh | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 8ba1a698611e..b3c976bc98c8 100755
@@ -203,10 +203,10 @@ event_options() {
 			per_event_options $INSTANCE/events/$group/$event
 		done
 	done
-	retry=0
-	while [ $retry -lt 3 ]; do
+	while [ "$UNRESOLVED_EVENTS" ]; do
+		prev_unresolved=$UNRESOLVED_EVENTS
 		retry_unresolved
-		retry=$((retry + 1))
+		[ "$prev_unresolved" = "$UNRESOLVED_EVENTS" ] && break
 	done
 	if [ "$UNRESOLVED_EVENTS" ]; then
 		cat 1>&2 << EOF

2.53.0

The xbc shell helpers interpolate bootconfig keys into regular expressions. Dots in keys consequently match arbitrary characters: asking for ftrace.options can also return ftraceXoptions. Branch and subkey lookups also match unrelated keys that merely share the requested prefix.

Compare complete keys literally and require a dot at descendant boundaries. Keep the optional subkey pattern operating on the suffix only.

---
The helper checks cover literal dotted keys, missing keys, branch boundaries and subkey selection. The original helpers passed one of five checks; the fixed helpers pass all five. These checks also pass when combined with the other fixes in this series.

 tools/bootconfig/scripts/xbc.sh | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

index 1f0ebf50dd2d..16ee590661b4 100644
@@ -36,21 +36,26 @@ xbc_get_val() { # key [maxnum]
 	if [ "$2" ]; then
 		MAXOPT="-L $2"
 	fi
-	grep "^$1 =" $XBC_TMPFILE | cut -d= -f2- | \
+	awk -v key="$1" '$1 == key && $2 == "="' "$XBC_TMPFILE" | cut -d= -f2- | \
 		sed -e 's/", /" /g' -e "s/',/' /g" | \
 		xargs $MAXOPT -n 1 echo
 }
 
 xbc_has_key() { # key
-	grep -q "^$1 =" $XBC_TMPFILE
+	awk -v key="$1" '$1 == key && $2 == "=" { found = 1 }
+		END { exit !found }' "$XBC_TMPFILE"
 }
 
 xbc_has_branch() { # prefix-key
-	grep -q "^$1" $XBC_TMPFILE
+	awk -v key="$1" '$1 == key || index($1, key ".") == 1 { found = 1 }
+		END { exit !found }' "$XBC_TMPFILE"
 }
 
 xbc_subkeys() { # prefix-key depth [subkey-pattern]
 	__keys=`echo $1 | sed "s/\./ /g"`
 	__s=`nr_args $__keys`
-	grep "^$1$3" $XBC_TMPFILE | cut -d= -f1| cut -d. -f$((__s + 1))-$((__s + $2)) | uniq
+	awk -v key="$1" -v pattern="$3" '
+		index($1, key ".") == 1 &&
+		substr($1, length(key) + 1) ~ ("^" pattern) { print $1 }
+	' "$XBC_TMPFILE" | cut -d. -f$((__s + 1))-$((__s + $2)) | uniq
 }

2.53.0