On Sat, May 11, 2024 at 12:46:41PM +0800, Zorro Lang wrote:
> On Fri, May 10, 2024 at 08:17:54AM -0700, Darrick J. Wong wrote:
> > On Fri, May 10, 2024 at 12:33:39PM +0800, Zorro Lang wrote:
> > > To avoid the dependence of debugfs, tracefs is mounted on another
> > > place -- /sys/kernel/tracing now. But for the compatibility, the
> > > /sys/kernel/debug/tracing is still there. So change _require_ftrace
> > > helper, try to use the new /sys/kernel/tracing path at first, or
> > > fallback to the old one if it's not supported.
> > >
> > > xfs/499 uses ftrace, so call _require_ftrace in it.
> > >
> > > Signed-off-by: Zorro Lang <zlang@xxxxxxxxxx>
> > > ---
> > > common/tracing | 13 +++++++++----
> > > tests/xfs/499 | 6 +++---
> > > 2 files changed, 12 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/common/tracing b/common/tracing
> > > index b3051c27..8613d044 100644
> > > --- a/common/tracing
> > > +++ b/common/tracing
> > > @@ -4,11 +4,16 @@
> > > #
> > > # Routines for dealing with ftrace (or any other tracing).
> > >
> > > -FTRACE_INSTANCES_DIR="/sys/kernel/debug/tracing/instances/"
> > > -
> > > _require_ftrace() {
> > > - test -d "$FTRACE_INSTANCES_DIR" || \
> > > - _notrun "kernel does not support ftrace"
> > > + if [ -d /sys/kernel/tracing/instances/ ];then
> > > + FTRACE_ROOT="/sys/kernel/tracing"
> > > + FTRACE_INSTANCES_DIR="/sys/kernel/tracing/instances"
> >
> > To answer my own question, this new path has been in Debian since at
> > least 2021.
>
> Oh, I thought the /sys/kernel/tracing was created in linux v4.1 :
> cc31004a4aa7 ("tracefs: Add directory /sys/kernel/tracing")
>
> But might be used in different distro widely later.
That creates an empty /sys/kernel/tracing directory, but userspace still
has to mount something to it, hence
/lib/systemd/system/sys-kernel-tracing.mount.
--D
> >
> > > + elif [ -d /sys/kernel/debug/tracing/instances/ ];then
> > > + FTRACE_ROOT="/sys/kernel/debug/tracing"
> > > + FTRACE_INSTANCES_DIR="/sys/kernel/debug/tracing/instances"
> > > + else
> > > + _notrun "The ftrace is not supported, or tracefs is not mounted"
> > > + fi
> > > }
> > >
> > > _ftrace_cleanup() {
> > > diff --git a/tests/xfs/499 b/tests/xfs/499
> > > index 9672f95d..883415dc 100755
> > > --- a/tests/xfs/499
> > > +++ b/tests/xfs/499
> > > @@ -14,18 +14,18 @@ _begin_fstest auto quick
> > > _register_cleanup "_cleanup" BUS
> > >
> > > # Import common functions.
> > > +. ./common/tracing
> >
> > You could probably get rid of the "Import common functions" comment.
>
> Sure, will change that when I merge it.
>
> >
> > This looks good!
> > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Thanks,
> Zorro
>
> >
> > --D
> >
> > >
> > > # real QA test starts here
> > > _supported_fs xfs
> > > +_require_ftrace
> > > _require_command "$CC_PROG" "cc"
> > >
> > > cprog=$tmp.ftrace.c
> > > oprog=$tmp.ftrace
> > > sedprog=$tmp.ftrace.sed
> > >
> > > -ftrace_dir=$DEBUGFS_MNT/tracing/events/xfs
> > > -
> > > -test -d $ftrace_dir || _notrun "ftrace not enabled"
> > > +ftrace_dir=$FTRACE_ROOT/events/xfs
> > >
> > > # The second argument to __print_symbolic is stringified in the tracepoint's
> > > # fmt file, so we look for "{ NUM, STRING }" and try to separate each of them
> > > --
> > > 2.44.0
> > >
> > >
> >
>
