linux-kernel - RE: [PATCH v5 0/3] close

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Date:   Sun, 7 Jun 2020 12:31:19 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christian Brauner' <christian.brauner@...ntu.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
CC:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kyle Evans <self@...e-evans.net>,
        Victor Stinner <victor.stinner@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Florian Weimer <fweimer@...hat.com>,
        Jann Horn <jannh@...gle.com>, Oleg Nesterov <oleg@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Shuah Khan <shuah@...nel.org>,
        David Howells <dhowells@...hat.com>,
        "Dmitry V. Levin" <ldv@...linux.org>
Subject: RE: [PATCH v5 0/3] close_range()

From: Christian Brauner
> Sent: 04 June 2020 00:24
..
> -struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
> +struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int *errorp)

Shouldn't this get changed to use ERR_PTR() etc?

..
> -int __close_range(struct files_struct *files, unsigned fd, unsigned max_fd)
> +int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)

If the lowest fd that had ever has CLOEXEC (or CLOFORK) set were
remembered a flag could be passed in to say 'only close the fd
with CLOEXEC set'.

Given that CLOEXEC is almost never cleared, and is typically set
on all but a few fd the 'optimisation' of the bitmap is
probably a pessimisation.

	David

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