net: Disambiguate kernel message

On Mon, Jan 30, 2012 at 08:22:03PM -0800, Bjorn Helgaas wrote:
> > We print a different message depending on whether we're out
> > of TCP memory or there are too many orphan sockets.
> 
> This patch mentions pairs of messages that are almost the same, but
> not quite.  If they're supposed to be different, I'd suggest making
> them clearly different.  As it is, the differences look like careless
> mistakes:

Good point. Updated patch changes the existing printks to be
the same as well.

On 1/31/12 12:51 AM, Christoph Paasch wrote:

>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -2015,10 +2015,22 @@ adjudge_to_death:
>>   	}
>>   	if (sk->sk_state != TCP_CLOSE) {
>>   		sk_mem_reclaim(sk);
>> -		if (tcp_too_many_orphans(sk, 0)) {
>> +		bool too_many_orphans = tcp_too_many_orphans(sk, 0);
>> +		bool out_of_socket_memory = tcp_out_of_memory(sk);
> 
> This introduces a compiler warning because you have the declarations
> after the code (sk_mem_reclaim()):
> 

Fixed by the patch below.

 -Arun

From 505717e51b15304b0bf50fc9dfed43fd06fad09a Mon Sep 17 00:00:00 2001
From: Arun Sharma <asharma@fb.com>
Date: Mon, 30 Jan 2012 14:16:06 -0800
Subject: [PATCH] net: Disambiguate kernel message

Some of our machines were reporting:

TCP: too many of orphaned sockets

even when the number of orphaned sockets was well below the
limit.

We print a different message depending on whether we're out
of TCP memory or there are too many orphaned sockets.

Signed-off-by: Arun Sharma <asharma@fb.com>
Suggested-by: Mohan Srinivasan <mohan@fb.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: David Miller <davem@davemloft.net>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Ingo Molnar <mingo@elte.hu>
---
 include/net/tcp.h    |   12 ++++++++----
 net/ipv4/tcp.c       |   17 +++++++++++++++--
 net/ipv4/tcp_timer.c |   12 +++++++++---
 3 files changed, 32 insertions(+), 9 deletions(-)

On Tue, 2012-01-31 at 10:15 -0800, Arun Sharma wrote:
> On Mon, Jan 30, 2012 at 08:22:03PM -0800, Bjorn Helgaas wrote:
> > > We print a different message depending on whether we're out
> > > of TCP memory or there are too many orphan sockets.
> > 
> > This patch mentions pairs of messages that are almost the same, but
> > not quite.  If they're supposed to be different, I'd suggest making
> > them clearly different.  As it is, the differences look like careless
> > mistakes:
> 
> Good point. Updated patch changes the existing printks to be
> the same as well.
[]
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
[]
> @@ -2014,11 +2014,24 @@ adjudge_to_death:
[]
> +		if (too_many_orphans) {
>  			if (net_ratelimit())
> -				printk(KERN_INFO "TCP: too many of orphaned "
> +				printk(KERN_INFO "TCP: too many orphaned "
>  				       "sockets\n");
> +		}
> +
> +		if (out_of_socket_memory) {
> +			if (net_ratelimit())
> +				printk(KERN_INFO "TCP: out of memory. "
> +				       "Consider tuning tcp_mem\n");
> +		}
> +
[]
> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
[]
> @@ -77,9 +78,14 @@ static int tcp_out_of_resources(struct sock *sk, int do_reset)
[]
> +	too_many_orphans = tcp_too_many_orphans(sk, shift);
> +	out_of_socket_memory = tcp_out_of_memory(sk);
> +	if (too_many_orphans || out_of_socket_memory) {
> +		if (out_of_socket_memory && net_ratelimit())
> +			printk(KERN_INFO "TCP: out of memory. "
> +					 "Consider tuning tcp_mem\n");
> +		if (too_many_orphans && net_ratelimit())
> +			printk(KERN_INFO "TCP: too many orphaned sockets\n");

These 2 blocks emit the messages in different order.

It might be useful to use a generic routine.

void tcp_log_oom(bool orphans, bool socket_memory)
{
	if (!net_ratelimit())
		return;
	if (orphans)
		pr_info("too many orphaned sockets\n");
	if (socket_memory)
		pr_info("out of socket memory - consider tuning tcp_mem\n");
}

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* Arun Sharma <asharma@fb.com> wrote:

> +				printk(KERN_INFO "TCP: too many orphaned "
>  				       "sockets\n");

> +				printk(KERN_INFO "TCP: out of memory. "
> +				       "Consider tuning tcp_mem\n");

> +			printk(KERN_INFO "TCP: out of memory. "
> +					 "Consider tuning tcp_mem\n");
> +		if (too_many_orphans && net_ratelimit())
> +			printk(KERN_INFO "TCP: too many orphaned sockets\n");

A small detail: please don't line break user-visible strings in 
mid sentence. Just keep the line long. Makes it much easier to 
search for the source of a kernel message:

   git grep "TCP: too many orphaned sockets"

Thanks,

	Ingo
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