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linux/net/rds
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santosh.shilimkar@oracle.com 7b4b000951 RDS: fix rds-ping deadlock over TCP transport 
Sowmini found hang with rds-ping while testing RDS over TCP. Its
a corner case and doesn't happen always. The issue is not reproducible
with IB transport. Its clear from below dump why we see it with RDS TCP.

 [<ffffffff8153b7e5>] do_tcp_setsockopt+0xb5/0x740
 [<ffffffff8153bec4>] tcp_setsockopt+0x24/0x30
 [<ffffffff814d57d4>] sock_common_setsockopt+0x14/0x20
 [<ffffffffa096071d>] rds_tcp_xmit_prepare+0x5d/0x70 [rds_tcp]
 [<ffffffffa093b5f7>] rds_send_xmit+0xd7/0x740 [rds]
 [<ffffffffa093bda2>] rds_send_pong+0x142/0x180 [rds]
 [<ffffffffa0939d34>] rds_recv_incoming+0x274/0x330 [rds]
 [<ffffffff810815ae>] ? ttwu_queue+0x11e/0x130
 [<ffffffff814dcacd>] ? skb_copy_bits+0x6d/0x2c0
 [<ffffffffa0960350>] rds_tcp_data_recv+0x2f0/0x3d0 [rds_tcp]
 [<ffffffff8153d836>] tcp_read_sock+0x96/0x1c0
 [<ffffffffa0960060>] ? rds_tcp_recv_init+0x40/0x40 [rds_tcp]
 [<ffffffff814d6a90>] ? sock_def_write_space+0xa0/0xa0
 [<ffffffffa09604d1>] rds_tcp_data_ready+0xa1/0xf0 [rds_tcp]
 [<ffffffff81545249>] tcp_data_queue+0x379/0x5b0
 [<ffffffffa0960cdb>] ? rds_tcp_write_space+0xbb/0x110 [rds_tcp]
 [<ffffffff81547fd2>] tcp_rcv_established+0x2e2/0x6e0
 [<ffffffff81552602>] tcp_v4_do_rcv+0x122/0x220
 [<ffffffff81553627>] tcp_v4_rcv+0x867/0x880
 [<ffffffff8152e0b3>] ip_local_deliver_finish+0xa3/0x220

This happens because rds_send_xmit() chain wants to take
sock_lock which is already taken by tcp_v4_rcv() on its
way to rds_tcp_data_ready(). Commit db6526dcb5 ("RDS: use
rds_send_xmit() state instead of RDS_LL_SEND_FULL") which
was trying to opportunistically finish the send request
in same thread context.

But because of above recursive lock hang with RDS TCP,
the send work from rds_send_pong() needs to deferred to
worker to avoid lock up. Given RDS ping is more of connectivity
test than performance critical path, its should be ok even
for transport like IB.

Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by:  Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-18 22:45:55 -07:00
..
af_rds.c RDS: Use per-bucket rw lock for bind hash-table 2015-09-30 12:43:25 -04:00
bind.c RDS: Invoke ->laddr_check() in rds_bind() for explicitly bound transports. 2015-10-13 04:22:40 -07:00
cong.c rds: rds_cong_queue_updates needs to defer the congestion update transmission 2015-02-11 14:35:44 -08:00
connection.c RDS: Use a single TCP socket for both send and receive. 2015-10-05 03:34:51 -07:00
ib.c RDS: IB: split mr pool to improve 8K messages performance 2015-10-05 11:19:02 -07:00
ib.h RDS: IB: split mr pool to improve 8K messages performance 2015-10-05 11:19:02 -07:00
ib_cm.c RDS: IB: handle rds_ibdev release case instead of crashing the kernel 2015-10-05 11:19:01 -07:00
ib_rdma.c RDS: IB: split mr pool to improve 8K messages performance 2015-10-05 11:19:02 -07:00
ib_recv.c RDS: IB: ack more receive completions to improve performance 2015-10-05 11:19:01 -07:00
ib_ring.c
ib_send.c RDS: IB: split send completion handling and do batch ack 2015-10-05 11:19:01 -07:00
ib_stats.c RDS: IB: split mr pool to improve 8K messages performance 2015-10-05 11:19:02 -07:00
ib_sysctl.c net: Convert uses of typedef ctl_table to struct ctl_table 2013-06-13 02:36:09 -07:00
info.c rds: fix an integer overflow test in rds_info_getsockopt() 2015-08-03 15:20:16 -07:00
info.h
iw.c Changes for 4.3 2015-09-09 08:33:31 -07:00
iw.h rds: switch ->inc_copy_to_user() to passing iov_iter 2014-11-24 05:16:43 -05:00
iw_cm.c RDS-TCP: Make RDS-TCP work correctly when it is set up in a netns other than init_net 2015-08-07 11:29:57 -07:00
iw_rdma.c RDS: Convert to ib_alloc_mr 2015-08-30 18:08:46 -04:00
iw_recv.c rds: switch ->inc_copy_to_user() to passing iov_iter 2014-11-24 05:16:43 -05:00
iw_ring.c
iw_send.c RDS: Convert to ib_alloc_mr 2015-08-30 18:08:46 -04:00
iw_stats.c
iw_sysctl.c rds: remove the unneed NULL checking 2014-05-09 15:59:45 -04:00
Kconfig net/rds: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:40:02 -08:00
loop.c RDS: use gfp flags from caller in conn_alloc() 2012-03-22 19:29:58 -04:00
loop.h
Makefile Net: rds: Makefile: Remove deprecated items 2010-11-22 08:16:15 -08:00
message.c rds: Make rds_message_copy_from_user() return 0 on success. 2015-02-07 22:41:56 -08:00
page.c net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
rdma.c RDS: Fix rds MR reference count in rds_rdma_unuse() 2015-08-25 16:28:10 -07:00
rdma_transport.c RDS: check for valid cm_id before initiating connection 2015-08-25 13:35:31 -07:00
rdma_transport.h rds: make local functions/variables static 2010-10-21 04:26:39 -07:00
rds.h Merge branch 'net/rds/4.3-v3' of git://git.kernel.org/pub/scm/linux/kernel/git/ssantosh/linux 2015-10-08 04:38:37 -07:00
recv.c net: Remove iocb argument from sendmsg and recvmsg 2015-03-02 13:06:31 -05:00
send.c RDS: fix rds-ping deadlock over TCP transport 2015-10-18 22:45:55 -07:00
stats.c net/rds: zero last byte for strncpy 2013-03-08 00:35:44 -05:00
sysctl.c net: rds: use correct size for max unacked packets and bytes 2015-02-04 16:07:27 -08:00
tcp.c RDS-TCP: Do not bloat sndbuf/rcvbuf in rds_tcp_tune 2015-10-05 03:34:53 -07:00
tcp.h RDS-TCP: Support multiple RDS-TCP listen endpoints, one per netns. 2015-08-07 11:29:58 -07:00
tcp_connect.c RDS-TCP: Support multiple RDS-TCP listen endpoints, one per netns. 2015-08-07 11:29:58 -07:00
tcp_listen.c RDS-TCP: Reset tcp callbacks if re-using an outgoing socket in rds_tcp_accept_one() 2015-10-13 04:22:41 -07:00
tcp_recv.c rds: switch ->inc_copy_to_user() to passing iov_iter 2014-11-24 05:16:43 -05:00
tcp_send.c RDS-TCP: Set up MSG_MORE and MSG_SENDPAGE_NOTLAST as appropriate in rds_tcp_xmit 2015-10-05 03:34:53 -07:00
tcp_stats.c net: rds: fix const array syntax 2011-07-01 16:16:19 -07:00
threads.c RDS: use rds_send_xmit() state instead of RDS_LL_SEND_FULL 2015-10-05 11:19:01 -07:00
transport.c RDS-TCP: Make RDS-TCP work correctly when it is set up in a netns other than init_net 2015-08-07 11:29:57 -07:00