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Date:   Fri, 18 Oct 2019 14:48:37 +0200
From:   Sebastian Sewior <bigeasy@linutronix.de>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        David Miller <davem@davemloft.net>,
        Daniel Borkmann <daniel@iogearbox.net>,
        bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
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        Peter Zijlstra <peterz@infradead.org>,
        Clark Williams <williams@redhat.com>
Subject: Re: [PATCH] BPF: Disable on PREEMPT_RT
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On 2019-10-18 13:28:21 [+0200], Thomas Gleixner wrote:
> The local lock is a 'sleeping' spinlock on RT (PI support) and as any other

it is a "per-CPU 'sleeping' spinlock on RT". Which means that it can be
acquired on multiple CPUs simultaneously (same like
preempt_disable(),…).

> RT substituted lock it also ensures that the task cannot be migrated when
> it is held, which makes per cpu assumptions work - the kernel has lots of
> them. :)
…
> 	tglx

Sebastian