linux-kernel - Do we need to disable preemption in flush_tlb

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Message-ID: <1519917189.13866.6.camel@synopsys.com>
Date:   Thu, 1 Mar 2018 15:13:10 +0000
From:   Alexey Brodkin <Alexey.Brodkin@...opsys.com>
To:     Vineet Gupta <Vineet.Gupta1@...opsys.com>
CC:     "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
Subject: Do we need to disable preemption in flush_tlb_range()?

Hi Vineet,

Just noticed that in comments for smp_call_function_many() it is said that
preemption must be disabled during its execution. And that function gets executed
among other ways like that:
-------------------------->8-----------------------
  flush_tlb_range()
    -> on_each_cpu_mask()
         -> smp_call_function_many()
-------------------------->8-----------------------

I'm not seeing right now any real problem with current implementation but
some architectures do that thus the question.

-Alexey