From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Christian Brauner <christian@brauner.io>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org
Subject: Re: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:39:53 +0200 [thread overview]
Message-ID: <82d34133-e174-efc3-48ed-332304028595@rasmusvillemoes.dk> (raw)
In-Reply-To: <20190521113448.20654-1-christian@brauner.io>
On 21/05/2019 13.34, Christian Brauner wrote:
> The performance is striking. For good measure, comparing the following
> simple close_all_fds() userspace implementation that is essentially just
> glibc's version in [6]:
>
> static int close_all_fds(void)
> {
> DIR *dir;
> struct dirent *direntp;
>
> dir = opendir("/proc/self/fd");
> if (!dir)
> return -1;
>
> while ((direntp = readdir(dir))) {
> int fd;
> if (strcmp(direntp->d_name, ".") == 0)
> continue;
> if (strcmp(direntp->d_name, "..") == 0)
> continue;
> fd = atoi(direntp->d_name);
> if (fd == 0 || fd == 1 || fd == 2)
> continue;
> close(fd);
> }
>
> closedir(dir); /* cannot fail */
> return 0;
> }
Before anybody copy-pastes this, please note that it lacks a check for
fd == dirfd(dir). If all of /proc/self/fd is returned in the first
getdents() syscall one won't notice, but...
Rasmus
next prev parent reply other threads:[~2019-05-21 13:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 11:34 [PATCH 1/2] open: add close_range() Christian Brauner
2019-05-21 11:34 ` [PATCH 2/2] tests: add close_range() tests Christian Brauner
2019-05-21 12:09 ` [PATCH 1/2] open: add close_range() Florian Weimer
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:23 ` Christian Brauner
2019-05-21 13:39 ` Rasmus Villemoes [this message]
2019-05-21 15:00 ` Al Viro
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:30 ` David Howells
2019-05-21 16:41 ` Christian Brauner
2019-05-21 20:23 ` Linus Torvalds
2019-05-22 8:12 ` Christian Brauner
2019-05-21 19:20 ` Al Viro
2019-05-21 19:59 ` Matthew Wilcox
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