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author | KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> | 2010-08-24 16:05:48 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2010-08-25 23:02:48 -0700 |
commit | d84ba638e4ba3c40023ff997aa5e8d3ed002af36 (patch) | |
tree | 45bff01d15301cb6fc2f27d53fdfcbbf1f2355b1 /net | |
parent | c5ed63d66f24fd4f7089b5a6e087b0ce7202aa8e (diff) | |
download | linux-stable-d84ba638e4ba3c40023ff997aa5e8d3ed002af36.tar.gz linux-stable-d84ba638e4ba3c40023ff997aa5e8d3ed002af36.tar.bz2 linux-stable-d84ba638e4ba3c40023ff997aa5e8d3ed002af36.zip |
tcp: select(writefds) don't hang up when a peer close connection
This issue come from ruby language community. Below test program
hang up when only run on Linux.
% uname -mrsv
Linux 2.6.26-2-486 #1 Sat Dec 26 08:37:39 UTC 2009 i686
% ruby -rsocket -ve '
BasicSocket.do_not_reverse_lookup = true
serv = TCPServer.open("127.0.0.1", 0)
s1 = TCPSocket.open("127.0.0.1", serv.addr[1])
s2 = serv.accept
s2.close
s1.write("a") rescue p $!
s1.write("a") rescue p $!
Thread.new {
s1.write("a")
}.join'
ruby 1.9.3dev (2010-07-06 trunk 28554) [i686-linux]
#<Errno::EPIPE: Broken pipe>
[Hang Here]
FreeBSD, Solaris, Mac doesn't. because Ruby's write() method call
select() internally. and tcp_poll has a bug.
SUS defined 'ready for writing' of select() as following.
| A descriptor shall be considered ready for writing when a call to an output
| function with O_NONBLOCK clear would not block, whether or not the function
| would transfer data successfully.
That said, EPIPE situation is clearly one of 'ready for writing'.
We don't have read-side issue because tcp_poll() already has read side
shutdown care.
| if (sk->sk_shutdown & RCV_SHUTDOWN)
| mask |= POLLIN | POLLRDNORM | POLLRDHUP;
So, Let's insert same logic in write side.
- reference url
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/31065
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/31068
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/tcp.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index e2add5ff9cb1..3fb1428e526e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -451,7 +451,8 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) mask |= POLLOUT | POLLWRNORM; } - } + } else + mask |= POLLOUT | POLLWRNORM; if (tp->urg_data & TCP_URG_VALID) mask |= POLLPRI; |