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Message-ID: <20200103085634.6xkgb4aonivjhfnq@comp-core-i7-2640m-0182e6> Date: Fri, 3 Jan 2020 09:56:34 +0100 From: Alexey Gladkov <gladkov.alexey@...il.com> To: J Freyensee <why2jjj.linux@...il.com> Cc: LKML <linux-kernel@...r.kernel.org>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, Linux API <linux-api@...r.kernel.org>, Linux FS Devel <linux-fsdevel@...r.kernel.org>, Linux Security Module <linux-security-module@...r.kernel.org>, Akinobu Mita <akinobu.mita@...il.com>, Alexander Viro <viro@...iv.linux.org.uk>, Alexey Dobriyan <adobriyan@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Andy Lutomirski <luto@...nel.org>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, "Dmitry V . Levin" <ldv@...linux.org>, "Eric W . Biederman" <ebiederm@...ssion.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...nel.org>, "J . Bruce Fields" <bfields@...ldses.org>, Jeff Layton <jlayton@...chiereds.net>, Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Oleg Nesterov <oleg@...hat.com>, Solar Designer <solar@...nwall.com>, Stephen Rothwell <sfr@...b.auug.org.au> Subject: Re: [PATCH v6 07/10] proc: flush task dcache entries from all procfs instances On Mon, Dec 30, 2019 at 02:03:29PM -0800, J Freyensee wrote: > > +#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? These inline helpers are introduced to improve readability. They only make sense inside procfs. I don't think that defensive programming is useful here. -- Rgrds, legion
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