From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: "Wu, Fengguang" <fengguang.wu@intel.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Eric Paris <eparis@redhat.com>, Nick Piggin <npiggin@suse.de>,
Andi Kleen <andi@firstfloor.org>,
David Howells <dhowells@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos
Date: Mon, 18 Jan 2010 12:22:14 +0900 [thread overview]
Message-ID: <20100118122214.1d13a3e4.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <6CADD16F56BC954D8E28F3836FA7ED7112A9CD50F6@shzsmsx501.ccr.corp.intel.com>
On Mon, 18 Jan 2010 11:15:38 +0800
"Wu, Fengguang" <fengguang.wu@intel.com> wrote:
> Hi,
>
> [replying from webmail, sorry for top-posting]
>
> memory_lseek() calls force_successful_syscall_return() to force success on negative vals.
> However that is a no-op for x86.
>
> My experiment shows that lseek() does return negative pos. However,
> manual says that "a value of (off_t) -1 is returned" on error. So it's OK
> as long as your program is written as "err == -1" instead of "err < 0".
>
On error, the kernel returns -EOVERFLOW (via %eax) and libc hides
it by
errno = EOVERFLOW
ret = -1
The problem discussed here is the kernel's return value. So, the kernel's
lseek should check that, I think.
Anyway, this lseek problem is not related to this patch itself and has
existed for very long time. Fixing it later by another patch is not very
bad, I think.
(I'm sorry I myself is not ready for writing a patch...)
Thaks,
-Kame
next prev parent reply other threads:[~2010-01-18 3:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-15 1:39 [PATCH 0/6] FMODE_NONOTIFY, FMODE_RANDOM and FMODE_NEG_OFFSET bits Wu Fengguang
2010-01-15 1:39 ` [PATCH 1/6] fanotify: fix FMODE_NONOTIFY bit number Wu Fengguang
2010-01-15 1:39 ` [PATCH 2/6] bitops: compile time optimization for hweight_long(CONSTANT) Wu Fengguang
2010-01-15 1:39 ` [PATCH 3/6] vfs: O_* bit numbers uniqueness check Wu Fengguang
2010-01-15 1:39 ` [PATCH 4/6] vfs: take f_lock on modifying f_mode after open time Wu Fengguang
2010-01-15 1:39 ` [PATCH 5/6] readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM Wu Fengguang
2010-01-15 1:40 ` [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos Wu Fengguang
2010-01-16 12:54 ` OGAWA Hirofumi
2010-01-18 0:15 ` KAMEZAWA Hiroyuki
2010-01-18 1:17 ` OGAWA Hirofumi
2010-01-18 1:25 ` KAMEZAWA Hiroyuki
2010-01-18 1:38 ` OGAWA Hirofumi
2010-01-18 2:00 ` KAMEZAWA Hiroyuki
2010-01-18 2:13 ` OGAWA Hirofumi
2010-01-18 2:30 ` KAMEZAWA Hiroyuki
2010-01-18 3:15 ` Wu, Fengguang
2010-01-18 3:22 ` KAMEZAWA Hiroyuki [this message]
2010-01-18 5:26 ` Wu, Fengguang
2010-01-19 0:37 ` KAMEZAWA Hiroyuki
2010-01-18 1:32 ` OGAWA Hirofumi
2010-01-18 1:49 ` KAMEZAWA Hiroyuki
2010-01-18 1:59 ` OGAWA Hirofumi
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