linux-kernel - Re: [PATCH 1/3] bpf: Don't check for current being NULL

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Message-ID: <1838884.qlCOuH57mO@blindfold>
Date:   Tue, 17 Oct 2017 00:23:13 +0200
From:   Richard Weinberger <richard@....at>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Al Viro <viro@....linux.org.uk>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>, linux-arch@...r.kernel.org
Subject: Re: [PATCH 1/3] bpf: Don't check for current being NULL

Alexei,

Am Dienstag, 17. Oktober 2017, 00:06:08 CEST schrieb Alexei Starovoitov:
> On Mon, Oct 16, 2017 at 11:18 AM, Richard Weinberger <richard@....at> wrote:
> > current is never NULL.
> > 
> > Signed-off-by: Richard Weinberger <richard@....at>
> > ---
> > 
> >  kernel/bpf/helpers.c | 12 ------------
> >  1 file changed, 12 deletions(-)
> > 
> > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> > index 3d24e238221e..e8845adcd15e 100644
> > --- a/kernel/bpf/helpers.c
> > +++ b/kernel/bpf/helpers.c
> > @@ -120,9 +120,6 @@ BPF_CALL_0(bpf_get_current_pid_tgid)
> > 
> >  {
> >  
> >         struct task_struct *task = current;
> > 
> > -       if (unlikely(!task))
> > -               return -EINVAL;
> > -
> 
> really? in all context? including irq and nmi?

I would be astonished current is NULL in such a context.

To be sure, let's CC linux-arch.
IIRC I talked also with Al about this and he also assumed that current
cannot be NULL.

Thanks,
//richard