linux-kernel - Re: [PATCH] Documentation: preempt-locking: Use better example

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Message-ID: <20181012113656.771e8dd1@lwn.net>
Date:   Fri, 12 Oct 2018 11:36:56 -0600
From:   Jonathan Corbet <corbet@....net>
To:     Andrew Murray <andrew.murray@....com>
Cc:     Robert Love <rml@...h9.net>, kpreempt-tech@...ts.sourceforge.net,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Documentation: preempt-locking: Use better example

On Mon,  8 Oct 2018 14:15:15 +0100
Andrew Murray <andrew.murray@....com> wrote:

> The existing wording implies that the use of spin_unlock whilst irqs are
> disabled might trigger a reschedule. However the preemptible() test in
> preempt_schedule will prevent a reschedule if irqs are disabled.
> 
> Lets improve the clarity of this wording to change the example from
> spin_unlock to cond_resched() and cond_resched_lock() as these are
> functions that will trigger a reschedule if the preempt count is 0 without
> testing that irqs are disabled.
> 
> Also remove the 'Last Updated' line as this is not up to date and better
> tracked via GIT.
> 
> Signed-off-by: Andrew Murray <andrew.murray@....com>

I've applied this, but that document is ... old.  It sure would be nice if
somebody found the energy to write a proper locking document for current
kernels...:)

Thanks,

jon