linux/net
Neil Horman bd7c4b604a netpoll: convert mutex into a semaphore
Bart Van Assche recently reported a warning to me:

<IRQ>  [<ffffffff8103d79f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff8103d7fa>] warn_slowpath_null+0x1a/0x20
[<ffffffff814761dd>] mutex_trylock+0x16d/0x180
[<ffffffff813968c9>] netpoll_poll_dev+0x49/0xc30
[<ffffffff8136a2d2>] ? __alloc_skb+0x82/0x2a0
[<ffffffff81397715>] netpoll_send_skb_on_dev+0x265/0x410
[<ffffffff81397c5a>] netpoll_send_udp+0x28a/0x3a0
[<ffffffffa0541843>] ? write_msg+0x53/0x110 [netconsole]
[<ffffffffa05418bf>] write_msg+0xcf/0x110 [netconsole]
[<ffffffff8103eba1>] call_console_drivers.constprop.17+0xa1/0x1c0
[<ffffffff8103fb76>] console_unlock+0x2d6/0x450
[<ffffffff8104011e>] vprintk_emit+0x1ee/0x510
[<ffffffff8146f9f6>] printk+0x4d/0x4f
[<ffffffffa0004f1d>] scsi_print_command+0x7d/0xe0 [scsi_mod]

This resulted from my commit ca99ca14c which introduced a mutex_trylock
operation in a path that could execute in interrupt context.  When mutex
debugging is enabled, the above warns the user when we are in fact
exectuting in interrupt context
interrupt context.

After some discussion, It seems that a semaphore is the proper mechanism to use
here.  While mutexes are defined to be unusable in interrupt context, no such
condition exists for semaphores (save for the fact that the non blocking api
calls, like up and down_trylock must be used when in irq context).

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Bart Van Assche <bvanassche@acm.org>
CC: Bart Van Assche <bvanassche@acm.org>
CC: David Miller <davem@davemloft.net>
CC: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-05-01 15:00:24 -04:00
..
9p
802 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-22 20:32:51 -04:00
8021q net: vlan: fix up vlan_proto_idx() for CONFIG_BUG=n 2013-04-21 15:58:19 -04:00
appletalk appletalk: info leak in ->getname() 2013-04-25 01:47:58 -04:00
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-07 18:37:01 -04:00
ax25 ax25: fix info leak via msg_name in ax25_recvmsg() 2013-04-07 16:28:00 -04:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
bluetooth Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2013-04-29 15:31:57 -04:00
bridge bridge: avoid OOPS if root port not found 2013-04-30 15:51:08 -04:00
caif caif: Remove bouncing address for Daniel Martensson 2013-04-23 13:25:51 -04:00
can Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-22 20:32:51 -04:00
ceph
core netpoll: convert mutex into a semaphore 2013-05-01 15:00:24 -04:00
dcb rtnetlink: Remove passing of attributes into rtnl_doit functions 2013-03-22 10:31:16 -04:00
dccp
decnet decnet: remove duplicated include from dn_table.c 2013-04-07 17:12:01 -04:00
dns_resolver
dsa dsa: fix freeing of sparse port allocation 2013-03-25 12:23:41 -04:00
ethernet net: add ETH_P_802_3_MIN 2013-03-28 01:20:42 -04:00
ieee802154 ieee802154/nl-mac.c: make some MLME operations optional 2013-04-08 12:00:16 -04:00
ipv4 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
ipv6 net: Add MIB counters for checksum errors 2013-04-29 15:14:03 -04:00
ipx
irda irda: irlmp_reasons[] can be static 2013-04-25 01:42:06 -04:00
iucv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-22 20:32:51 -04:00
key Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec 2013-03-27 14:07:04 -04:00
l2tp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-07 18:37:01 -04:00
lapb
llc llc: Fix missing msg_namelen update in llc_ui_recvmsg() 2013-04-07 16:28:01 -04:00
mac80211 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2013-04-24 10:54:20 -04:00
mac802154 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
netlabel
netlink netlink: Fix skb ref counting. 2013-05-01 14:57:03 -04:00
netrom netrom: info leak in ->getname() 2013-04-25 01:47:58 -04:00
nfc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
openvswitch openvswitch: Remove unneeded ovs_netdev_get_ifindex() 2013-04-30 00:19:11 -04:00
packet sock_diag: allow to dump bpf filters 2013-04-29 13:21:30 -04:00
phonet rtnetlink: Remove passing of attributes into rtnl_doit functions 2013-03-22 10:31:16 -04:00
rds
rfkill Merge branch 'for-john' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next 2013-04-22 14:58:14 -04:00
rose rose: fix info leak via msg_name in rose_recvmsg() 2013-04-07 16:28:02 -04:00
rxrpc
sched net_sched: act_ipt forward compat with xtables 2013-05-01 13:19:19 -04:00
sctp net: sctp: minor: remove dead code from sctp_packet 2013-04-22 16:25:21 -04:00
sunrpc NFS client bugfixes for Linux 3.9 2013-04-10 09:00:51 -07:00
tipc tipc: add InfiniBand media type 2013-04-17 14:18:33 -04:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
vmw_vsock Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-30 03:55:20 -04:00
wimax
wireless Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2013-04-24 10:54:20 -04:00
x25
xfrm Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2013-04-11 16:14:37 -04:00
compat.c
Kconfig netlink: mmaped netlink: ring setup 2013-04-19 14:57:57 -04:00
Makefile
nonet.c
socket.c net: socket: move ktime2ts to ktime header api 2013-04-19 16:39:13 -04:00
sysctl_net.c