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Jiri Kosina 59ea33a68a tcp: perform DMA to userspace only if there is a task waiting for it 
Back in 2006, commit 1a2449a87b ("[I/OAT]: TCP recv offload to I/OAT")
added support for receive offloading to IOAT dma engine if available.

The code in tcp_rcv_established() tries to perform early DMA copy if
applicable. It however does so without checking whether the userspace
task is actually expecting the data in the buffer.

This is not a problem under normal circumstances, but there is a corner
case where this doesn't work -- and that's when MSG_TRUNC flag to
recvmsg() is used.

If the IOAT dma engine is not used, the code properly checks whether
there is a valid ucopy.task and the socket is owned by userspace, but
misses the check in the dmaengine case.

This problem can be observed in real trivially -- for example 'tbench' is a
good reproducer, as it makes a heavy use of MSG_TRUNC. On systems utilizing
IOAT, you will soon find tbench waiting indefinitely in sk_wait_data(), as they
have been already early-copied in tcp_rcv_established() using dma engine.

This patch introduces the same check we are performing in the simple
iovec copy case to the IOAT case as well. It fixes the indefinite
recvmsg(MSG_TRUNC) hangs.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-27 13:45:51 -07:00
..
9p net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
802 tokenring: delete all remaining driver support 2012-05-15 20:23:16 -04:00
8021q netpoll: move np->dev and np->dev_name init into __netpoll_setup() 2012-07-17 09:02:36 -07:00
appletalk net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
atm net: Remove casts to same type 2012-06-04 11:45:11 -04:00
ax25 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-10 23:56:33 -07:00
bluetooth Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
bridge net: fix race condition in several drivers when reading stats 2012-07-22 12:12:32 -07:00
caif Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
can can: gw: Remove pointless casts 2012-07-10 22:36:17 +02:00
ceph Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-07-24 10:01:50 -07:00
core net: fix rtnetlink IFF_PROMISC and IFF_ALLMULTI handling 2012-07-27 13:45:50 -07:00
dcb net: Fix non-kernel-doc comments with kernel-doc start marker 2012-07-10 23:13:45 -07:00
dccp ipv4: Prepare for change of rt->rt_iif encoding. 2012-07-23 16:36:26 -07:00
decnet decnet: Don't set RTCF_DIRECTSRC. 2012-07-23 13:16:59 -07:00
dns_resolver Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2012-05-21 20:27:36 -07:00
dsa dsa: Convert compare_ether_addr to ether_addr_equal 2012-05-09 20:49:19 -04:00
ethernet ipx: move peII functions 2012-07-19 10:48:00 -07:00
ieee802154 6lowpan: Change byte order when storing/accessing to len field 2012-07-16 22:52:02 -07:00
ipv4 tcp: perform DMA to userspace only if there is a task waiting for it 2012-07-27 13:45:51 -07:00
ipv6 ipv6: Early TCP socket demux 2012-07-26 15:50:39 -07:00
ipx ipx: move peII functions 2012-07-19 10:48:00 -07:00
irda irda: Fix typo in irda 2012-07-16 23:23:52 -07:00
iucv net: remove skb_orphan_try() 2012-06-15 15:30:15 -07:00
key net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
l2tp net: l2tp_eth: provide tx_dropped counter 2012-06-29 00:52:32 -07:00
lapb lapb: Neaten debugging 2012-05-17 18:45:20 -04:00
llc net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
mac80211 Merge branch 'for-3.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds 2012-07-26 20:26:27 -07:00
mac802154 mac802154: sparse warnings: make symbols static 2012-07-12 07:54:45 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
netlabel netlabel: use GFP flags from caller instead of GFP_ATOMIC 2012-03-22 19:29:57 -04:00
netlink genetlink: define lockdep_genl_is_held() when CONFIG_LOCKDEP 2012-07-24 00:01:30 -07:00
netrom net: Convert all sysctl registrations to register_net_sysctl 2012-04-20 21:22:30 -04:00
nfc Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
openvswitch Revert "openvswitch: potential NULL deref in sample()" 2012-07-27 13:45:51 -07:00
packet net: added support for 40GbE link. 2012-06-27 15:42:24 -07:00
phonet net: remove my future former mail address 2012-06-17 16:29:38 -07:00
rds rds: set correct msg_namelen 2012-07-23 01:01:44 -07:00
rfkill rfkill: Add the capability to switch all devices of all type in __rfkill_switch_all(). 2012-06-06 15:18:17 -04:00
rose net: Convert all sysctl registrations to register_net_sysctl 2012-04-20 21:22:30 -04:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-10 23:56:33 -07:00
sched ipv4: Prepare for change of rt->rt_iif encoding. 2012-07-23 16:36:26 -07:00
sctp ipv4: Prepare for change of rt->rt_iif encoding. 2012-07-23 16:36:26 -07:00
sunrpc ipv6: add ipv6_addr_hash() helper 2012-07-18 11:28:46 -07:00
tipc tipc: remove print_buf and deprecated log buffer code 2012-07-13 19:34:43 -04:00
unix net: make sock diag per-namespace 2012-07-16 22:31:34 -07:00
wanrouter wanmain: comparing array with NULL 2012-07-24 13:55:21 -07:00
wimax net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
wireless Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
x25 net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
xfrm net: Document dst->obsolete better. 2012-07-20 13:31:21 -07:00
compat.c net: Fix references to out-of-scope variables in put_cmsg_compat() 2012-07-22 17:50:49 -07:00
Kconfig net: drop NET dependency from HAVE_BPF_JIT 2012-05-21 12:50:12 -07:00
Makefile econet: remove ancient bug ridden protocol 2012-05-18 01:35:08 -04:00
nonet.c
socket.c net: netprio_cgroup: rework update socket logic 2012-07-22 12:44:01 -07:00
sysctl_net.c net: delete all instances of special processing for token ring 2012-05-15 20:14:35 -04:00