linux-kernel - Re: [PATCH 02/10] exit: Add and use make_task

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Date:   Wed, 5 Jan 2022 23:34:59 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Alexey Gladkov <legion@...nel.org>,
        Kyle Huey <me@...ehuey.com>, Oleg Nesterov <oleg@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>
Subject: Re: [PATCH 02/10] exit: Add and use make_task_dead.

On Wed, Jan 05, 2022 at 02:51:05PM -0800, Linus Torvalds wrote:
> On Wed, Jan 5, 2022 at 1:53 PM Al Viro <viro@...iv.linux.org.uk> wrote:
> >
> > On Wed, Jan 05, 2022 at 02:46:10PM -0600, Eric W. Biederman wrote:
> > >
> > > Being in assembly it did not have anything after the name do_exit so it
> > > hid from my regex "[^A-Za-z0-9_]do_exit[^A-Za-z0-9]".  Thank you for
> > > finding that.
> >
> > Umm...  What's wrong with '\<do_exit\>'?
> 
> Christ people, you both make it so complicated.
> 
> If you want to search for 'do_exit', just do
> 
>         git grep -w do_exit
> 
> where that '-w' does exactly that "word boundary" thing.

Sure.

> I thought everybody knew about this, because it's such a common thing
> to do - checking my shell history, more than a third of my "git grep"
> uses use '-w', exactly because it's very convenient for identifier
> lookup
> 
> But yes, in more complex cases where you have other parts to the
> pattern (ie you're not looking *just* for a single word), by all means
> use '\<' and/or '\>'.

Yep.  I wanted to make it clear that you really don't need that kind
of horrors ([^A-Za-z0-9_]); sure, on the ends of regex you just need
-w and that's it, but it's not needed in more convoluted cases either.

BTW, it doesn't have to be "have other parts of pattern" - IME the typical
case when -w is not enough is something like

git grep -n '\<wait_for_completion'