On Sat, May 13, 2023 at 09:52:46AM +0000, Zhuo, Qiuxu wrote:
> > From: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > ...
> > > >>>> I wish diff was better at showing what really changed. The meld
> > > >>>> tool can help but its gui...
> > > >>>>
> > > >>>> Should I run meld later (I'm out at a conference so no access to
> > > >>>> meld-capable
> > > >>>> machines) or are we sufficiently confident that the lines were
> > > >>>> moved as-is ? :)
> > > >>>>
> > > >>>
> > > >>> Thank you, Joel for this concern. Good to know the meld diff GUI tool.
> > > >>> I just run the command below and confirmed that the lines were
> > > >>> moved
> > > >>> as-is: rcu_scale_{cleanup,shutdown}() follows kfree_scale_cleanup().
> > > >>> You may double check it ;-).
> > > >>>
> > > >>> meld --diff ./rcuscale.c.before ./rcuscale.c.after
> > > >>
> > > >> Nice, thank you both!
> > > >>
> > > >> Another option is to check out the commit corresponding to this
> > > >> patch, then do "git blame -M kernel/rcu/rcuscale.c". Given a
> > > >> move-only commit, there should be no line tagged with this commit's
> > SHA-1.
> > > >
> > > > Just had a good experiment with the "git blame -M" option:
> > > > - Used this option to prove a move-only commit quickly (no line tagged
> > with that commit) (the fastest method to me).
> > > > - Then just only needed to quickly check the positions of the moved code
> > chunk by myself (easy).
> > > >
> > > > Thank you, Paul for sharing this. It's very useful to me.
> > >
> > > Looks good to me as well and thank you both for sharing the tips.
> >
> > Here is one way to script this, where "SHA" identifies the commit to be
> > checked and PATHS the affected pathnames:
> >
> > git checkout SHA^
> > git show SHA | git apply -
> > git blame -M PATHS | grep '^0* '
>
> Cool ~. Thank you, Paul.
> I took them and made them into a script below for future use ;-)
Nice!!!
> #!/bin/bash
>
> SHA=$1
>
> if [ -z "$SHA" ]; then
> echo "Usage: $0 <commit-id>"
> exit 1
> fi
>
> if ! git cat-file -t "$SHA" &> /dev/null; then
> echo "$SHA does not exist in the repository"
> exit 1
> fi
You might want to record the current position so that you can return
to it automatically. One approach is to parse the output of
"git status".
> git checkout ${SHA}^ &> /dev/null
> git show ${SHA} | git apply - &> /dev/null
>
> PATHS=`git status| grep "modified:" | cut -d: -f2 | xargs`
The '--porcelain' argument makes 'git status' is a bit easier to parse
robustly.
> for P in ${PATHS}; do
> R=`git blame -M $P | grep '^0* '`
You can avoid any bash-variable length limitations by using
'grep -q' and capturing the exit status using "$?".
Thanx, Paul
> if test -n "$R"; then
> echo "$SHA is NOT a move-only commit"
> exit 1
> fi
> done
>
> echo "$SHA is a move-only commit"
>
> > If there is no output, there were no non-move changes.
> >
> > Or just do the "git blame -M PATHS | grep '^0* '" before doing the checking.
> >
> > And yes, you can derive PATHS using "git status" if you want. ;-)
> > Thanx, Paul
