linux-kernel - Re: [RFC patch 07/19] bpf: Provide BPF_PROG_RUN_PIN_ON

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Date:   Fri, 14 Feb 2020 20:36:09 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.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>
Subject: Re: [RFC patch 07/19] bpf: Provide BPF_PROG_RUN_PIN_ON_CPU() macro

Mathieu Desnoyers <mathieu.desnoyers@...icios.com> writes:

> On 14-Feb-2020 02:39:24 PM, Thomas Gleixner wrote:
> [...]
>> +#define BPF_PROG_RUN_PIN_ON_CPU(prog, ctx) ({				\
>> +	u32 ret;							\
>> +	migrate_disable();						\
>> +	ret = __BPF_PROG_RUN(prog, ctx, bpf_dispatcher_nopfunc);	\
>> +	migrate_enable();						\
>> +	ret; })
>
> Does it really have to be a statement expression with a local variable ?
>
> If so, we should consider renaming "ret" to "__ret" to minimize the
> chances of a caller issuing BPF_PROG_RUN_PIN_ON_CPU with "ret" as
> prog or ctx argument, which would lead to unexpected results.

Indeed. That really can be an inline.

Thanks,

        tglx