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Date:   Tue, 1 Jun 2021 18:41:15 +0100
From:   Will Deacon <will@kernel.org>
To:     Daniel Borkmann <daniel@iogearbox.net>
Cc:     Yanfei Xu <yanfei.xu@windriver.com>, ast@kernel.org,
        zlim.lnx@gmail.com, catalin.marinas@arm.com, andrii@kernel.org,
        kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
        john.fastabend@gmail.com, kpsingh@kernel.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache
Message-ID: <20210601174114.GA29130@willie-the-truck>
References: <20210601150625.37419-1-yanfei.xu@windriver.com>
 <20210601150625.37419-2-yanfei.xu@windriver.com>
 <56cc1e25-25c3-a3da-64e3-8a1c539d685b@iogearbox.net>
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On Tue, Jun 01, 2021 at 07:20:04PM +0200, Daniel Borkmann wrote:
> On 6/1/21 5:06 PM, Yanfei Xu wrote:
> > It's no need to trigger IPI for keeping pipeline fresh in bpf case.
> 
> This needs a more concrete explanation/analysis on "why it is safe" to do so
> rather than just saying that it is not needed.

Agreed. You need to show how the executing thread ends up going through a
context synchronizing operation before jumping to the generated code if
the IPI here is removed.

Will