netdev - Re: extended bpf_send_signal

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Message-ID: <YBfIUwtK+QqVlfRt@hirez.programming.kicks-ass.net>
Date:   Mon, 1 Feb 2021 10:22:27 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, andrii@...nel.org,
        Martin KaFai Lau <kafai@...com>,
        David Miller <davem@...emloft.net>, kpsingh@...nel.org,
        John Fastabend <john.fastabend@...il.com>,
        netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: extended bpf_send_signal_thread with argument

On Sun, Jan 31, 2021 at 12:14:02PM +0100, Dmitry Vyukov wrote:
> Hi,
> 
> I would like to send a signal from a bpf program invoked from a
> perf_event. There is:

You can't. Sending signals requires sighand lock, and you're not allowed
to take locks from perf_event context.