Re: [PATCH] selftests/ftrace: refactor eprobes test to fix argument checks

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

On Tue,  4 Aug 2026 21:46:35 +0200
Martin Kaiser <martin@kaiser.cx> wrote:

> The add/remove eprobe test installs an eprobe for the openat syscall and
> runs ls. It checks the filenames that were opened by ls against a
> whitelist and a blacklist.
> 
> Commit 206b25c09080 ("tracing: eprobe: read the complete FILTER_PTR_STRING
> pointer") fixed access to some string fields in eprobes. This triggers
> test failures as the blacklist does not allow relative paths for the
> openat parameters.
> 
> What makes this test unstable is the fact that the openat calls vary a
> lot between different systems.
> 
> Refactor the test to make it more robust. "cd <directory>" will issue a
> chdir syscall with the target directory as parameter. Set an eprobe on
> the sys_enter_chdir event and filter for the exact directory name. Allow
> (fault) as fallback.
> 
Looks good to me.

Fixes: 206b25c09080 ("tracing: eprobe: read the complete FILTER_PTR_STRING pointer")

Since it is already merged to linus tree.
Let me pick it.

> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202607151010.b68428e1-lkp@intel.com
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>

Thanks!

> ---
>  .../ftrace/test.d/dynevent/add_remove_eprobe.tc  | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> index c300eb020262..e2322693d0c3 100644
> --- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> @@ -1,16 +1,16 @@
>  #!/bin/sh
>  # SPDX-License-Identifier: GPL-2.0
>  # description: Generic dynamic event - add/remove eprobe events
> -# requires: dynamic_events events/syscalls/sys_enter_openat "<attached-group>.<attached-event> [<args>]":README
> +# requires: dynamic_events events/syscalls/sys_enter_chdir "<attached-group>.<attached-event> [<args>]":README
>  
>  echo 0 > events/enable
>  
>  clear_dynamic_events
>  
>  SYSTEM="syscalls"
> -EVENT="sys_enter_openat"
> +EVENT="sys_enter_chdir"
>  FIELD="filename"
> -EPROBE="eprobe_open"
> +EPROBE="eprobe_chdir"
>  OPTIONS="file=+0(\$filename):ustring"
>  echo "e:$EPROBE $SYSTEM/$EVENT $OPTIONS" >> dynamic_events
>  
> @@ -18,20 +18,14 @@ grep -q "$EPROBE" dynamic_events
>  test -d events/eprobes/$EPROBE
>  
>  echo 1 > events/eprobes/$EPROBE/enable
> -ls
> +cd /sys/kernel/tracing
>  echo 0 > events/eprobes/$EPROBE/enable
>  
> -content=`grep '^ *ls-' trace | grep 'file='`
> -nocontent=`grep '^ *ls-' trace | grep 'file=' | grep -v -e '"/' -e '"."' -e '(fault)' ` || true
> -
> +content=`grep -e 'file="/sys/kernel/tracing"\|(fault)' trace`
>  if [ -z "$content" ]; then
>  	exit_fail
>  fi
>  
> -if [ ! -z "$nocontent" ]; then
> -	exit_fail
> -fi
> -
>  echo "-:$EPROBE" >> dynamic_events
>  
>  ! grep -q "$EPROBE" dynamic_events
> -- 
> 2.43.7
> 


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