From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
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: Thu, 24 Jan 2019 18:34:03 -0800 [thread overview]
Message-ID: <20190125023402.34a5k62furpdismi@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <395a3741-70c9-c345-08a4-77bc3bd3cae2@gmail.com>
On Thu, Jan 24, 2019 at 06:29:55PM -0800, Eric Dumazet wrote:
>
>
> On 01/24/2019 03:58 PM, Alexei Starovoitov wrote:
> > On Thu, Jan 24, 2019 at 07:01:09PM +0100, Peter Zijlstra wrote:
>
> >> and from NMI ...
> >
> > progs are not preemptable and map syscall accessors have bpf_prog_active counters.
> > So nmi/kprobe progs will not be running when syscall is running.
> > Hence dead lock is not possible and irq_save is not needed.
>
>
> Speaking of NMI, how pcpu_freelist_push() and pop() can actually work ?
>
> It seems bpf_get_stackid() can be called from NMI, and lockdep seems to complain loudly
it's a known false positive.
https://lkml.org/lkml/2018/7/25/756
and the same answer as before:
we're not going to penalize performance to shut up false positive.
next prev parent reply other threads:[~2019-01-25 2:34 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 [this message]
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
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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