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From: "Michael Kerrisk" <mtk.manpages@gmail.com>
To: "Andrew Morton" <akpm@linux-foundation.org>
Cc: subrata@linux.vnet.ibm.com, linux-arch@vger.kernel.org,
	drepper@redhat.com, linux-kernel@vger.kernel.org,
	torvalds@linux-foundation.org, linux-api@vger.kernel.org,
	linux-man@vger.kernel.org, davidel@xmailserver.org,
	netdev@vger.kernel.org, roland@redhat.com, oleg@tv-sign.ru,
	hch@lst.de, davem@davemloft.net, alan@redhat.com,
	jakub@redhat.com
Subject: Re: [PATCH] reintroduce accept4
Date: Fri, 14 Nov 2008 10:24:06 -0500	[thread overview]
Message-ID: <517f3f820811140724x43fcc114o434b384fbeb6449e@mail.gmail.com> (raw)
In-Reply-To: <20081113140541.23754cad.akpm@linux-foundation.org>

>> Andrew, you noted a lack of explanation accompanying the original
>> patch.  Here's something to fill the gap, and which may be suitable
>> for the changelog.
>>
>> ==
>> Introduce a new accept4() system call.  The addition of this system
>> call matches analogous changes in 2.6.27 (dup3(), evenfd2(),
>> signalfd4(), inotify_init1(), epoll_create1(), pipe2()) which added
>> new system calls that differed from analogous traditional system calls
>> in adding a flags argument that can be used to access additional
>> functionality. The accept4() system call is exactly the same as
>> accept(), except that it adds a flags bit-mask argument.  Two flags
>> are initially implemented.  (Most of the new system calls in 2.6.27
>> also had both of these flags.)  SOCK_CLOEXEC causes the close-on-exec
>> (FD_CLOEXEC) flag to be enabled for the new file descriptor returned
>> by accept4().  This is a useful security feature to avoid leaking
>> information in a multithreaded program where one thread is doing an
>> accept() at the same time as another thread is doing a fork() plus
>> exec().  (More details here:
>> http://udrepper.livejournal.com/20407.html "Secure File Descriptor
>> Handling", Ulrich Drepper)  The other flag is SOCK_NONBLOCK, which
>> causes the O_NONBLOCK flag to be enabled on the new open file
>> description created by accept4().  (This flag is merely a convenience,
>> saving the use of additional calls fcntl(F_GETFL) and fcntl (F_SETFL)
>> to achieve the same result.)
>
> I replaced the existing changelog with the above (plus some paragraph
> breaks ;)).  Will add the new test app when it comes along.

Git allows paragraph breaks in changelogs?!  You gotta love technology ;-).

-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/ Found a documentation bug?
http://www.kernel.org/doc/man-pages/reporting_bugs.html

      parent reply	other threads:[~2008-11-14 15:24 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-26 16:41 Ulrich Drepper
2008-10-28  3:41 ` Andrew Morton
2008-10-28  4:22   ` Ulrich Drepper
2008-10-28  4:52     ` Andrew Morton
2008-10-28 12:34 ` Michael Kerrisk
2008-11-13 21:51 ` Michael Kerrisk
2008-11-13 22:02   ` Michael Kerrisk
2008-11-13 22:11     ` Michael Kerrisk
2008-11-13 22:14       ` Michael Kerrisk
2008-11-13 22:05   ` Andrew Morton
2008-11-13 22:25     ` Paul Mackerras
2008-11-13 22:28       ` Paul Mackerras
2008-11-13 22:57         ` Andrew Morton
2008-11-14  0:07           ` David Miller
2008-11-14 15:24           ` Michael Kerrisk
2008-11-14 17:40           ` Michael Kerrisk
2008-11-14 15:24     ` Michael Kerrisk [this message]

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