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Subject: Re: [PATCH v6 07/10] proc: flush task dcache entries from all procfs
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To:     Alexey Gladkov <gladkov.alexey@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
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Cc:     Akinobu Mita <akinobu.mita@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Daniel Micay <danielmicay@gmail.com>,
        Djalal Harouni <tixxdz@gmail.com>,
        "Dmitry V . Levin" <ldv@altlinux.org>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
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References: <20191225125151.1950142-1-gladkov.alexey@gmail.com>
 <20191225125151.1950142-8-gladkov.alexey@gmail.com>
From:   J Freyensee <why2jjj.linux@gmail.com>
Message-ID: <8d85ba43-0759-358e-137d-246107bac747@gmail.com>
Date:   Mon, 30 Dec 2019 14:03:29 -0800
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snip

.

.

.

>   
> +#ifdef CONFIG_PROC_FS
> +static inline void pidns_proc_lock(struct pid_namespace *pid_ns)
> +{
> +	down_write(&pid_ns->rw_proc_mounts);
> +}
> +
> +static inline void pidns_proc_unlock(struct pid_namespace *pid_ns)
> +{
> +	up_write(&pid_ns->rw_proc_mounts);
> +}
> +
> +static inline void pidns_proc_lock_shared(struct pid_namespace *pid_ns)
> +{
> +	down_read(&pid_ns->rw_proc_mounts);
> +}
> +
> +static inline void pidns_proc_unlock_shared(struct pid_namespace *pid_ns)
> +{
> +	up_read(&pid_ns->rw_proc_mounts);
> +}
> +#else /* !CONFIG_PROC_FS */
> +
Apologies for my newbie question. I couldn't help but notice all these 
function calls are assuming that the parameter struct pid_namespace 
*pid_ns will never be NULL.  Is that a good assumption?

I don't have the background in this code to answer on my own, but I 
thought I'd raise the question.

Thanks,
Jay