linux-kernel - PROBLEM: poll and select report different status

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Date:	Sat, 4 Jul 2009 18:25:23 +0800
From:	Zhao Shuai <upczhsh@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: PROBLEM: poll and select report different status

[1.] One line summary of the problem:
select and poll report different status

[2.] Full description of the problem/report:
A reader and a writer opens a fifo, then close the reader side and poll & select
on the writer side. Surprisingly, poll and select reports different
status. Poll says
the writer fd is unreadable & writable, but select says it's
readable(writer fd is
a WRITE ONLY descriptor!) & writable.

[3.] Keywords (i.e., modules, networking, kernel):
kernel

[4.] Kernel information
[4.1.] Kernel version (from /proc/version):
Linux version 2.6.24-24-generic (buildd@...mer) (gcc version 4.2.4
(Ubuntu 4.2.4-1ubuntu4))

[7.] A small shell script or example program which triggers the
problem (if possible)
see the attached file.

--
Regards,
Zhao

View attachment "fifo_poll_select.c" of type "text/x-csrc" (1990 bytes)