[PATCH] tools/bootconfig: Preserve event trigger filters in ftrace2bconf.sh

[PATCH] tools/bootconfig: Preserve event trigger filters in ftrace2bconf.sh

[Eduardo Mucelli Rezende Oliveira]

ftrace2bconf.sh reads each trigger line into "action active", keeping
only its first whitespace-separated word. For example, a histogram with
"if common_pid > 0" is exported without its filter. Reapplying that
configuration installs an unconditional histogram instead.

Read the whole trigger line and remove only the trailing histogram state
marker. Quote the resulting action so that whitespace in a filter is
preserved in the exported configuration.

Fixes: 2b86062a34a8 ("tools/bootconfig: Add a script to generates bootconfig from ftrace")
Signed-off-by: Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>
---
Hi Masami,

This is my third submission to the kernel. Feedback is welcome.

I tested this in a temporary tracefs instance on my Ubuntu machine,
running kernel 7.0.0-38-generic, with recording disabled. I installed
histograms with "if common_pid > 0" and 'if comm == "a b"', exported
them, then restored that instance's actions with bconf2ftrace.sh --apply.
The original exporter lost both filters. With this patch, both were
restored correctly. An unfiltered histogram worked in both cases.

Thanks,
Eduardo

 tools/bootconfig/scripts/ftrace2bconf.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/bootconfig/scripts/ftrace2bconf.sh b/tools/bootconfig/scripts/ftrace2bconf.sh
index f8f288f90c..0a066094f5 100755
--- a/tools/bootconfig/scripts/ftrace2bconf.sh
+++ b/tools/bootconfig/scripts/ftrace2bconf.sh
@@ -115,8 +115,10 @@ per_event_options() { # event-dir
 		done
 		DEFINED_VARS="$DEFINED_VARS "`defined_vars $evdir`
 	fi
-	grep -v "^#" $evdir/trigger | while read action active; do
-		emit_kv $PREFIX.event.$group.$event.actions += \'$action\'
+	grep -v "^#" $evdir/trigger |
+		sed 's/ \[\(active\|paused\)\]$//' |
+		while IFS= read -r action; do
+		emit_kv $PREFIX.event.$group.$event.actions += "'$action'"
 	done
 
 	if [ $GROUP_ENABLED -eq 0 ] && event_is_enabled $evdir/enable; then

base-commit: 22ab3094befd6ef37135e4a252c0da9cd755f75a
-- 
2.53.0

Re: [PATCH] tools/bootconfig: Preserve event trigger filters in ftrace2bconf.sh

[Masami Hiramatsu]

Hi Eduardo,

On Fri, 23 Oct 2026 10:49:46 +0200, Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com> wrote:
> ftrace2bconf.sh reads each trigger line into "action active", keeping
> only its first whitespace-separated word. For example, a histogram with
> "if common_pid > 0" is exported without its filter. Reapplying that
> configuration installs an unconditional histogram instead.
> 
> Read the whole trigger line and remove only the trailing histogram state
> marker. Quote the resulting action so that whitespace in a filter is
> preserved in the exported configuration.
> 
> Fixes: 2b86062a34a8 ("tools/bootconfig: Add a script to generates bootconfig from ftrace")
> Signed-off-by: Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>
> ---
> Hi Masami,
> 
> This is my third submission to the kernel. Feedback is welcome.

Please make your patches as a series of patches. You have sent the below patch
on the similar topic. Those should be one series.

https://lore.kernel.org/all/20261024110837.696216-1-edumucelli@gmail.com/

Also, the \[\(foo\|bar\)\] seems gnu extension. Can you consider using
more posix style like below?

-		sed 's/ \[\(active\|paused\)\]$//' |
+		sed -e 's/ \[active\]$//' -e 's/ \[paused\]$//' |

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

[PATCH v2 0/2] tools/bootconfig: Fix histogram filters and variable names

[Eduardo Mucelli Rezende Oliveira]

Hi Masami,

Thanks for the review. I've combined the two fixes into a series and
used the two sed expressions you suggested.

The first patch keeps filters when exporting event triggers. The second
handles underscores in histogram variable names, so the exporter keeps
histograms that depend on them.

Changes in v2:
- Send the two previously separate patches as one series.
- Use separate sed -e expressions for [active] and [paused], avoiding
  GNU sed's alternation extension in patch 1.
- No code changes to patch 2.

The original submissions are here:
https://lore.kernel.org/all/20261023084947.3264289-1-edumucelli@gmail.com/
https://lore.kernel.org/all/20261024110837.696216-1-edumucelli@gmail.com/

Feedback is welcome.

Thanks,
Eduardo

Eduardo Mucelli Rezende Oliveira (2):
  tools/bootconfig: Preserve event trigger filters in ftrace2bconf.sh
  tools/bootconfig: Recognize underscores in histogram variables

 tools/bootconfig/scripts/ftrace2bconf.sh | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)


base-commit: e28458ef30ad66ce7cd2299ec5ee8a8a016d67ff
-- 
2.53.0

[PATCH v2 1/2] tools/bootconfig: Preserve event trigger filters in ftrace2bconf.sh

[Eduardo Mucelli Rezende Oliveira]

ftrace2bconf.sh reads each trigger line into "action active", keeping
only its first whitespace-separated word. For example, a histogram with
"if common_pid > 0" is exported without its filter. Reapplying that
configuration installs an unconditional histogram instead.

Read the whole trigger line and remove only the trailing histogram state
marker. Quote the resulting action so that whitespace in a filter is
preserved in the exported configuration.

Fixes: 2b86062a34a8 ("tools/bootconfig: Add a script to generates bootconfig from ftrace")
Signed-off-by: Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>
---
I tested this in a temporary tracefs instance on my Ubuntu machine,
running kernel 7.0.0-38-generic, with recording disabled. I installed
histograms with "if common_pid > 0" and 'if comm == "a b"', exported
them, then restored that instance's actions with bconf2ftrace.sh --apply.
The original exporter lost both filters. With this patch, both were
restored correctly. An unfiltered histogram worked in both cases.

 tools/bootconfig/scripts/ftrace2bconf.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/bootconfig/scripts/ftrace2bconf.sh b/tools/bootconfig/scripts/ftrace2bconf.sh
index f8f288f90c74..032ac5b10a4a 100755
--- a/tools/bootconfig/scripts/ftrace2bconf.sh
+++ b/tools/bootconfig/scripts/ftrace2bconf.sh
@@ -115,8 +115,10 @@ per_event_options() { # event-dir
 		done
 		DEFINED_VARS="$DEFINED_VARS "`defined_vars $evdir`
 	fi
-	grep -v "^#" $evdir/trigger | while read action active; do
-		emit_kv $PREFIX.event.$group.$event.actions += \'$action\'
+	grep -v "^#" $evdir/trigger |
+		sed -e 's/ \[active\]$//' -e 's/ \[paused\]$//' |
+		while IFS= read -r action; do
+		emit_kv $PREFIX.event.$group.$event.actions += "'$action'"
 	done
 
 	if [ $GROUP_ENABLED -eq 0 ] && event_is_enabled $evdir/enable; then
-- 
2.53.0

[PATCH v2 2/2] tools/bootconfig: Recognize underscores in histogram variables

[Eduardo Mucelli Rezende Oliveira]

The variable dependency resolver in ftrace2bconf.sh only recognizes
letters and digits in histogram variable names. A reference such as
$start_ts is read as $start, and the start_ts definition is missed.
The consumer is repeatedly deferred and eventually omitted from the
export with an undefined-variable diagnostic.

Include underscores when matching both definitions and references so
that valid histogram variables are resolved and their consumers are
exported after the providers.

Fixes: 2b86062a34a8 ("tools/bootconfig: Add a script to generates bootconfig from ftrace")
Signed-off-by: Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>
---
The histogram-variable documentation even uses names such as wakeup_lat
and us_per_sec [1]. These are valid in tracefs, but the exporter cannot
resolve references to them and leaves out the dependent histogram.

I tested this in a temporary tracefs instance on my Ubuntu machine,
running kernel 7.0.0-38-generic, with recording disabled. I created a
provider histogram defining start_ts and a consumer using $start_ts.
The original exporter reported an undefined variable and left out the
consumer. With the fix, both were exported and restored correctly.
A separate pair using ts0 worked in both versions.

[1] https://docs.kernel.org/trace/histogram.html#histogram-variables

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

diff --git a/tools/bootconfig/scripts/ftrace2bconf.sh b/tools/bootconfig/scripts/ftrace2bconf.sh
index 032ac5b10a4a..b01297217cf3 100755
--- a/tools/bootconfig/scripts/ftrace2bconf.sh
+++ b/tools/bootconfig/scripts/ftrace2bconf.sh
@@ -88,10 +88,10 @@ DEFINED_VARS=
 UNRESOLVED_EVENTS=
 
 defined_vars() { # event-dir
-	grep "^hist" $1/trigger | grep -o ':[a-zA-Z0-9]*='
+	grep "^hist" $1/trigger | grep -o ':[a-zA-Z0-9_]*='
 }
 referred_vars() {
-	grep "^hist" $1/trigger | grep -o '$[a-zA-Z0-9]*'
+	grep "^hist" $1/trigger | grep -o '$[a-zA-Z0-9_]*'
 }
 
 event_is_enabled() { # enable-file
-- 
2.53.0