From: Peter Zijlstra <peterz@infradead•org>
To: Alexei Starovoitov <alexei.starovoitov@gmail•com>
Cc: Alexei Starovoitov <ast@kernel•org>,
davem@davemloft•net, daniel@iogearbox•net,
jakub.kicinski@netronome•com, netdev@vger•kernel.org,
kernel-team@fb•com, mingo@redhat•com, will.deacon@arm•com,
Paul McKenney <paulmck@linux•vnet.ibm.com>,
jannh@google•com
Subject: Re: [PATCH v4 bpf-next 1/9] bpf: introduce bpf_spin_lock
Date: Mon, 28 Jan 2019 09:24:52 +0100 [thread overview]
Message-ID: <20190128082452.GA28467@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190125234241.soomtkrgp2i7m7ul@ast-mbp.dhcp.thefacebook.com>
On Fri, Jan 25, 2019 at 03:42:43PM -0800, Alexei Starovoitov wrote:
> On Fri, Jan 25, 2019 at 10:10:57AM +0100, Peter Zijlstra wrote:
> > Do we want something like (the completely untested) below to avoid
> > having to manually audit this over and over?
> >
> > ---
> > include/linux/filter.h | 2 +-
> > include/linux/kernel.h | 9 +++++++--
> > kernel/sched/core.c | 28 ++++++++++++++++++++++++++++
> > 3 files changed, 36 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/filter.h b/include/linux/filter.h
> > index d531d4250bff..4ab51e78da36 100644
> > --- a/include/linux/filter.h
> > +++ b/include/linux/filter.h
> > @@ -513,7 +513,7 @@ struct sk_filter {
> > struct bpf_prog *prog;
> > };
> >
> > -#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi)
> > +#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); })
>
> That looks reasonable and I intent to apply this patch to bpf-next after testing.
> Can you pls reply with a sob ?
Sure; with the caveat that I didn't even hold it near a compiler, and it
probably should grow a comment to explain the interface (similar to
might_sleep):
Suggested-by: Jann Horn <jannh@google•com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead•org>
> The easiest fix is to add preempt_disable/enable for socket filters.
> There is a concern that such fix will make classic bpf non-preemptable
> and classic bpf can be quite cpu expensive.
> Also on the receive side classic runs in bh, so 4k flow_dissector calls
> in classic has to be dealt with anyway.
Right and agreed; per that argument the worst case (legacy) BPF was
already present under non-preempt and thus making it consistently so
should not affect the worst case.
next prev parent reply other threads:[~2019-01-28 8:25 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-24 4:13 [PATCH v4 bpf-next 0/9] introduce bpf_spin_lock Alexei Starovoitov
2019-01-24 4:13 ` [PATCH v4 bpf-next 1/9] bpf: " Alexei Starovoitov
2019-01-24 18:01 ` Peter Zijlstra
2019-01-24 18:56 ` Peter Zijlstra
2019-01-24 23:42 ` Paul E. McKenney
2019-01-25 0:05 ` Alexei Starovoitov
2019-01-25 1:22 ` Paul E. McKenney
2019-01-25 1:46 ` Jann Horn
2019-01-25 2:38 ` Alexei Starovoitov
2019-01-25 4:27 ` Alexei Starovoitov
2019-01-25 4:31 ` Paul E. McKenney
2019-01-25 4:47 ` Alexei Starovoitov
2019-01-25 16:02 ` Paul E. McKenney
2019-01-25 4:11 ` Paul E. McKenney
2019-01-25 16:18 ` Jann Horn
2019-01-25 22:51 ` Paul E. McKenney
2019-01-25 23:44 ` Alexei Starovoitov
2019-01-26 0:43 ` Jann Horn
2019-01-26 0:59 ` Jann Horn
2019-01-24 23:58 ` Alexei Starovoitov
2019-01-25 0:18 ` Jann Horn
2019-01-25 2:49 ` Alexei Starovoitov
2019-01-25 2:29 ` Eric Dumazet
2019-01-25 2:34 ` Alexei Starovoitov
2019-01-25 2:44 ` Eric Dumazet
2019-01-25 2:57 ` Alexei Starovoitov
2019-01-25 8:38 ` Peter Zijlstra
2019-01-25 9:10 ` Peter Zijlstra
2019-01-25 23:42 ` Alexei Starovoitov
2019-01-28 8:24 ` Peter Zijlstra [this message]
2019-01-28 8:31 ` Peter Zijlstra
2019-01-28 8:35 ` Peter Zijlstra
2019-01-28 20:49 ` Alexei Starovoitov
2019-01-28 8:43 ` Peter Zijlstra
2019-01-28 21:37 ` Alexei Starovoitov
2019-01-29 8:59 ` Peter Zijlstra
2019-01-30 2:20 ` Alexei Starovoitov
2019-01-25 9:59 ` Peter Zijlstra
2019-01-25 10:09 ` Peter Zijlstra
2019-01-25 10:23 ` Peter Zijlstra
2019-01-26 0:17 ` bpf memory model. Was: " Alexei Starovoitov
2019-01-28 9:24 ` Peter Zijlstra
2019-01-28 21:56 ` Alexei Starovoitov
2019-01-29 9:16 ` Peter Zijlstra
2019-01-30 2:32 ` Alexei Starovoitov
2019-01-30 8:58 ` Peter Zijlstra
2019-01-30 19:36 ` Alexei Starovoitov
2019-01-30 18:11 ` Will Deacon
2019-01-30 18:36 ` Paul E. McKenney
2019-01-30 19:51 ` Alexei Starovoitov
2019-01-30 21:05 ` Paul E. McKenney
2019-01-30 22:57 ` Alexei Starovoitov
2019-01-31 14:01 ` Paul E. McKenney
2019-01-31 18:47 ` Alexei Starovoitov
2019-02-01 14:05 ` Paul E. McKenney
2019-01-30 19:50 ` Alexei Starovoitov
2019-01-24 4:13 ` [PATCH v4 bpf-next 2/9] bpf: add support for bpf_spin_lock to cgroup local storage Alexei Starovoitov
2019-01-24 4:13 ` [PATCH v4 bpf-next 3/9] tools/bpf: sync include/uapi/linux/bpf.h Alexei Starovoitov
2019-01-24 4:13 ` [PATCH v4 bpf-next 4/9] selftests/bpf: add bpf_spin_lock tests Alexei Starovoitov
2019-01-24 4:13 ` [PATCH v4 bpf-next 5/9] selftests/bpf: add bpf_spin_lock C test Alexei Starovoitov
2019-01-24 4:14 ` [PATCH v4 bpf-next 6/9] bpf: introduce BPF_F_LOCK flag Alexei Starovoitov
2019-01-24 4:14 ` [PATCH v4 bpf-next 7/9] tools/bpf: sync uapi/bpf.h Alexei Starovoitov
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