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Pavel Emelyanov cf7b708c8d Make access to task's nsproxy lighter ... When someone wants to deal with some other taks's namespaces it has to lock the task and then to get the desired namespace if the one exists. This is slow on read-only paths and may be impossible in some cases. E.g. Oleg recently noticed a race between unshare() and the (sent for review in cgroups) pid namespaces - when the task notifies the parent it has to know the parent's namespace, but taking the task_lock() is impossible there - the code is under write locked tasklist lock. On the other hand switching the namespace on task (daemonize) and releasing the namespace (after the last task exit) is rather rare operation and we can sacrifice its speed to solve the issues above. The access to other task namespaces is proposed to be performed like this: rcu_read_lock(); nsproxy = task_nsproxy(tsk); if (nsproxy != NULL) { / * * work with the namespaces here * e.g. get the reference on one of them * / } / * * NULL task_nsproxy() means that this task is * almost dead (zombie) * / rcu_read_unlock(); This patch has passed the review by Eric and Oleg :) and, of course, tested. [clg@fr.ibm.com: fix unshare()] [ebiederm@xmission.com: Update get_net_ns_by_pid] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		17 years ago
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9p	9p: remove sysctl	17 years ago
802	…
8021q	…
appletalk	[NET]: sparse warning fixes	17 years ago
atm	[BR2684]: get rid of broken header code.	17 years ago
ax25	…
bluetooth	…
bridge	…
core	Make access to task's nsproxy lighter	17 years ago
dccp	[DCCP]: fix link error with !CONFIG_SYSCTL	17 years ago
decnet	…
econet	…
ethernet	…
ieee80211	…
ipv4	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	17 years ago
ipv6	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	17 years ago
ipx	…
irda	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	17 years ago
iucv	…
key	…
lapb	…
llc	[NET]: Introduce and use print_mac() and DECLARE_MAC_BUF()	17 years ago
mac80211	[MAC80211]: only honor IW_SCAN_THIS_ESSID in STA, IBSS, and AP modes	17 years ago
netfilter	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	17 years ago
netlabel	[NETLINK]: Introduce nested and byteorder flag to netlink attribute	17 years ago
netlink	…
netrom	…
packet	…
rfkill	…
rose	…
rxrpc	KEYS: Make request_key() and co fundamentally asynchronous	17 years ago
sched	[NET]: fix carrier-on bug?	17 years ago
sctp	Remove "unsafe" from module struct	17 years ago
sunrpc	sysctl: remove broken sunrpc debug binary sysctls	17 years ago
tipc	…
unix	…
wanrouter	…
wireless	Driver core: change add_uevent_var to use a struct	17 years ago
x25	…
xfrm	[IPSEC]: Rename mode to outer_mode and add inner_mode	17 years ago
Kconfig	…
Makefile	…
TUNABLE	…
compat.c	…
nonet.c	…
socket.c	r/o bind mounts: filesystem helpers for custom 'struct file's	17 years ago
sysctl_net.c	…