Patchwork connector: Fix sid connector (was: Badness at kernel/softirq.c:143...)

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Submitter Christian Borntraeger
Date Sept. 29, 2009, 3:12 p.m.
Message ID <200909291712.33099.borntraeger@de.ibm.com>
Download mbox | patch
Permalink /patch/34438/
State Not Applicable
Delegated to: David Miller
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Comments

Christian Borntraeger - Sept. 29, 2009, 3:12 p.m.
Am Dienstag 29 September 2009 16:45:54 schrieb Oleg Nesterov:
> I think Christian's patch only needs the small fixup.

Oleg, Evgeniy,

just in case the discussion concludes that my patch is fine,
here is a fixed version.

[PATCH] connector: Fix sid connector

The sid connector gives the following warning:
Badness at kernel/softirq.c:143
[...]
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. We can safely move proc_sid_connector from
__set_special_pids to sys_setsid.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

---
 kernel/exit.c |    4 +---
 kernel/sys.c  |    2 ++
 2 files changed, 3 insertions(+), 3 deletions(-)

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Oleg Nesterov - Sept. 29, 2009, 4:28 p.m.
On 09/29, Christian Borntraeger wrote:
>
>
> The network code must not be called with disabled interrupts but
> sys_setsid holds the tasklist_lock with spinlock_irq while calling
> the connector. We can safely move proc_sid_connector from
> __set_special_pids to sys_setsid.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>
> ---
>  kernel/exit.c |    4 +---
>  kernel/sys.c  |    2 ++
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/kernel/exit.c
> ===================================================================
> --- linux-2.6.orig/kernel/exit.c
> +++ linux-2.6/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);
> Index: linux-2.6/kernel/sys.c
> ===================================================================
> --- linux-2.6.orig/kernel/sys.c
> +++ linux-2.6/kernel/sys.c
> @@ -1110,6 +1110,8 @@ SYSCALL_DEFINE0(setsid)
>  	err = session;
>  out:
>  	write_unlock_irq(&tasklist_lock);
> +	if (err > 0)
> +		proc_sid_connector(sid);
>  	return err;
>  }

Acked-by: Oleg Nesterov <oleg@redhat.com>

I'd suggest you to resend this patch to Andrew. Unless you know
another way to push it into Linus's tree ;)

Perhaps it makes sense to update the changelog, it should mention
the issues with daemonize().

Oleg.

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Evgeniy Polyakov - Sept. 29, 2009, 5:07 p.m.
On Tue, Sep 29, 2009 at 05:12:33PM +0200, Christian Borntraeger (borntraeger@de.ibm.com) wrote:
> just in case the discussion concludes that my patch is fine,
> here is a fixed version.
> 
> [PATCH] connector: Fix sid connector
> 
> The sid connector gives the following warning:
> Badness at kernel/softirq.c:143
> [...]
> 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. We can safely move proc_sid_connector from
> __set_special_pids to sys_setsid.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Looks good, thank you.
Ack.

Patch

Index: linux-2.6/kernel/exit.c
===================================================================
--- linux-2.6.orig/kernel/exit.c
+++ linux-2.6/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);
Index: linux-2.6/kernel/sys.c
===================================================================
--- linux-2.6.orig/kernel/sys.c
+++ linux-2.6/kernel/sys.c
@@ -1110,6 +1110,8 @@  SYSCALL_DEFINE0(setsid)
 	err = session;
 out:
 	write_unlock_irq(&tasklist_lock);
+	if (err > 0)
+		proc_sid_connector(sid);
 	return err;
 }