The following commit has been merged in the linux branch: commit 0d0df599f1f11f12d589318bacb59a50fb5c0310 Author: Christian Borntraeger borntraeger@de.ibm.com Date: Mon Oct 26 16:49:34 2009 -0700

connector: fix regression introduced by sid connector

Since commit 02b51df1b07b4e9ca823c89284e704cadb323cd1 (proc connector: add event for process becoming session leader) we have the following warning:

Badness at kernel/softirq.c:143 [...] Krnl PSW : 0404c00180000000 00000000001481d4 (local_bh_enable+0xb0/0xe0) [...] Call Trace: ([<000000013fe04100>] 0x13fe04100) [<000000000048a946>] sk_filter+0x9a/0xd0 [<000000000049d938>] netlink_broadcast+0x2c0/0x53c [<00000000003ba9ae>] cn_netlink_send+0x272/0x2b0 [<00000000003baef0>] proc_sid_connector+0xc4/0xd4 [<0000000000142604>] __set_special_pids+0x58/0x90 [<0000000000159938>] sys_setsid+0xb4/0xd8 [<00000000001187fe>] sysc_noemu+0x10/0x16 [<00000041616cb266>] 0x41616cb266

The warning is ---> WARN_ON_ONCE(in_irq() || irqs_disabled());

The network code must not be called with disabled interrupts but sys_setsid holds the tasklist_lock with spinlock_irq while calling the connector.

After a discussion we agreed that we can move proc_sid_connector from __set_special_pids to sys_setsid.

We also agreed that it is sufficient to change the check from task_session(curr) != pid into err > 0, since if we don't change the session, this means we were already the leader and return -EPERM.

One last thing: There is also daemonize(), and some people might want to get a notification in that case. Since daemonize() is only needed if a user space does kernel_thread this does not look important (and there seems to be no consensus if this connector should be called in daemonize). If we really want this, we can add proc_sid_connector to daemonize() in an additional patch (Scott?)

Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Cc: Scott James Remnant scott@ubuntu.com Cc: Matt Helsley matthltc@us.ibm.com Cc: David S. Miller davem@davemloft.net Acked-by: Oleg Nesterov oleg@redhat.com Acked-by: Evgeniy Polyakov zbr@ioremap.net Acked-by: David Rientjes rientjes@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/kernel/exit.c b/kernel/exit.c index e61891f..f7864ac 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -359,10 +359,8 @@ void __set_special_pids(struct pid *pid) { struct task_struct *curr = current->group_leader;

- if (task_session(curr) != pid) { + if (task_session(curr) != pid) change_pid(curr, PIDTYPE_SID, pid); - proc_sid_connector(curr); - }

if (task_pgrp(curr) != pid) change_pid(curr, PIDTYPE_PGID, pid); diff --git a/kernel/sys.c b/kernel/sys.c index 255475d..1828f8d 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1110,6 +1110,8 @@ SYSCALL_DEFINE0(setsid) err = session; out: write_unlock_irq(&tasklist_lock); + if (err > 0) + proc_sid_connector(group_leader); return err; }