| Submitter | jeff.liu |
|---|---|
| Date | Oct. 9, 2012, 4:57 a.m. |
| Message ID | <5073AEB7.9060309@oracle.com> |
| Download | mbox | patch |
| Permalink | /patch/190202/ |
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
Comments
From: Jeff Liu <jeff.liu@oracle.com> Date: Tue, 09 Oct 2012 12:57:27 +0800 > 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 <dan.carpenter@oracle.com> > CC: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com> > CC: David S. Miller <davem@davemloft.net> > CC: James Morris <james.l.morris@oracle.com> > Signed-off-by: Jie Liu <jeff.liu@oracle.com> Applied and queued up for -stable, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Patch
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;
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 <dan.carpenter@oracle.com> CC: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com> CC: David S. Miller <davem@davemloft.net> CC: James Morris <james.l.morris@oracle.com> Signed-off-by: Jie Liu <jeff.liu@oracle.com> --- net/rds/send.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)