From patchwork Tue Oct 9 04:57:27 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v2] RDS: fix rds-ping spinlock recursion Date: Mon, 08 Oct 2012 18:57:27 -0000 From: "jeff.liu" X-Patchwork-Id: 190202 Message-Id: <5073AEB7.9060309@oracle.com> To: rds-devel@oss.oracle.com Cc: Venkat Venkatsubra , davem@davemloft.net, Dan Carpenter , James Morris , netdev@vger.kernel.org Hello, This is the revised patch for fixing rds-ping spinlock recursion according to Venkat's suggestions. RDS ping/pong over TCP feature has been broken for years(2.6.39 to 3.6.0) since we have to set TCP cork and call kernel_sendmsg() between ping/pong which both need to lock "struct sock *sk". However, this lock has already been hold before rds_tcp_data_ready() callback is triggerred. As a result, we always facing spinlock resursion which would resulting in system panic. Given that RDS ping is only used to test the connectivity and not for serious performance measurements, we can queue the pong transmit to rds_wq as a delayed response. Reported-by: Dan Carpenter CC: Venkat Venkatsubra CC: David S. Miller CC: James Morris Signed-off-by: Jie Liu --- net/rds/send.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/rds/send.c b/net/rds/send.c index 96531d4..88eace5 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -1122,7 +1122,7 @@ rds_send_pong(struct rds_connection *conn, __be16 dport) rds_stats_inc(s_send_pong); if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags)) - rds_send_xmit(conn); + queue_delayed_work(rds_wq, &conn->c_send_w, 0); rds_message_put(rm); return 0;