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Subject: Re: [PATCH bpf] bpf: run bpf programs with preemption disabled
To:     Alexei Starovoitov <ast@kernel.org>, davem@davemloft.net
Cc:     peterz@infradead.org, jannh@google.com, paulmck@linux.ibm.com,
        will.deacon@arm.com, mingo@redhat.com, netdev@vger.kernel.org,
        kernel-team@fb.com
References: <20190129024334.1100196-1-ast@kernel.org>
From:   Daniel Borkmann <daniel@iogearbox.net>
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Date:   Thu, 31 Jan 2019 23:24:19 +0100
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On 01/29/2019 03:43 AM, Alexei Starovoitov wrote:
> Disabled preemption is necessary for proper access to per-cpu maps
> from BPF programs.
> 
> But the sender side of socket filters didn't have preemption disabled:
> unix_dgram_sendmsg->sk_filter->sk_filter_trim_cap->bpf_prog_run_save_cb->BPF_PROG_RUN
> 
> and a combination of af_packet with tun device didn't disable either:
> tpacket_snd->packet_direct_xmit->packet_pick_tx_queue->ndo_select_queue->
>   tun_select_queue->tun_ebpf_select_queue->bpf_prog_run_clear_cb->BPF_PROG_RUN
> 
> Disable preemption before executing BPF programs (both classic and extended).
> 
> Reported-by: Jann Horn <jannh@google.com>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Applied, thanks!