From 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 3 Feb 2014 19:13:49 -0800 Subject: namespaces: Use task_lock and not rcu to protect nsproxy The synchronous syncrhonize_rcu in switch_task_namespaces makes setns a sufficiently expensive system call that people have complained. Upon inspect nsproxy no longer needs rcu protection for remote reads. remote reads are rare. So optimize for same process reads and write by switching using rask_lock instead. This yields a simpler to understand lock, and a faster setns system call. In particular this fixes a performance regression observed by Rafael David Tinoco . This is effectively a revert of Pavel Emelyanov's commit cf7b708c8d1d7a27736771bcf4c457b332b0f818 Make access to task's nsproxy lighter from 2007. The race this originialy fixed no longer exists as do_notify_parent uses task_active_pid_ns(parent) instead of parent->nsproxy. Signed-off-by: "Eric W. Biederman" --- fs/proc/proc_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/proc/proc_net.c') diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 4677bb7dc7c2..a63af3e0a612 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -113,9 +113,11 @@ static struct net *get_proc_task_net(struct inode *dir) rcu_read_lock(); task = pid_task(proc_pid(dir), PIDTYPE_PID); if (task != NULL) { - ns = task_nsproxy(task); + task_lock(task); + ns = task->nsproxy; if (ns != NULL) net = get_net(ns->net_ns); + task_unlock(task); } rcu_read_unlock(); -- cgit v1.2.2 From e81324407269b7708a0678a5c40710d2a75e9bf0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 31 Jul 2014 03:22:30 -0700 Subject: proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net In oddball cases where the thread has a different network namespace than the primary thread group leader or more likely in cases where the thread remains and the thread group leader has exited this ensures that /proc/net continues to work. This should not cause any problems but if it does this patch can just be reverted. Signed-off-by: "Eric W. Biederman" --- fs/proc/proc_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/proc/proc_net.c') diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index a63af3e0a612..39481028ec08 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -226,7 +226,7 @@ static struct pernet_operations __net_initdata proc_net_ns_ops = { int __init proc_net_init(void) { - proc_symlink("net", NULL, "self/net"); + proc_symlink("net", NULL, "thread-self/net"); return register_pernet_subsys(&proc_net_ns_ops); } -- cgit v1.2.2