linux-kernel - Re: [patch V3 06/22] bpf/trace: Remove redundant preempt_disable from trace_call

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Message-ID: <8736aykfnk.fsf@nanos.tec.linutronix.de>
Date:   Tue, 25 Feb 2020 13:36:15 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        David Miller <davem@...emloft.net>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sebastian Sewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Clark Williams <williams@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Vinicius Costa Gomes <vinicius.gomes@...el.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [patch V3 06/22] bpf/trace: Remove redundant preempt_disable from trace_call_bpf()

Alexei Starovoitov <alexei.starovoitov@...il.com> writes:
> On Mon, Feb 24, 2020 at 09:42:52PM +0100, Thomas Gleixner wrote:
>> > But looking at your patch cant_sleep() seems unnecessary strong.
>> > Should it be cant_migrate() instead?
>> 
>> Yes, if we go with the migrate_disable(). OTOH, having a
>> preempt_disable() in that uprobe callsite should work as well, then we
>> can keep the cant_sleep() check which covers all other callsites
>> properly. No strong opinion though.
>
> ok. I went with preempt_disable() for uprobes. It's simpler.
> And pushed the whole set to bpf-next.
> In few days we'll send it to Dave for net-next and on the way
> to Linus's next release. imo it's a big milestone.
> Thank you for the hard work to make it happen.

Thank you for guidance and review!

      tglx