linux-kernel - Re: [PATCH net-next v4] bonding: rate-limit bonding driver inspect messages

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Message-ID: <20240220130735.GI40273@kernel.org>
Date: Tue, 20 Feb 2024 13:07:35 +0000
From: Simon Horman <horms@...nel.org>
To: Praveen Kumar Kannoju <praveen.kannoju@...cle.com>
Cc: j.vosburgh@...il.com, andy@...yhouse.net, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	rajesh.sivaramasubramaniom@...cle.com, rama.nichanamatlu@...cle.com,
	manjunath.b.patil@...cle.com
Subject: Re: [PATCH net-next v4] bonding: rate-limit bonding driver inspect
 messages

On Tue, Feb 20, 2024 at 10:34:37AM +0530, Praveen Kumar Kannoju wrote:
> Through the routine bond_mii_monitor(), bonding driver inspects and commits
> the slave state changes. During the times when slave state change and
> failure in aqcuiring rtnl lock happen at the same time, the routine
> bond_mii_monitor() reschedules itself to come around after 1 msec to commit
> the new state.
> 
> During this, it executes the routine bond_miimon_inspect() to re-inspect
> the state chane and prints the corresponding slave state on to the console.
> Hence we do see a message at every 1 msec till the rtnl lock is acquired
> and state chage is committed.
> 
> This patch doesn't change how bond functions. It only simply limits this
> kind of log flood.
> 
> Signed-off-by: Praveen Kumar Kannoju <praveen.kannoju@...cle.com>
> ---
> v4:
>   - Rectification in the patch subject and versioning details.
> v3: https://lore.kernel.org/lkml/20240219133721.4567-1-praveen.kannoju@oracle.com/
>   - Commit message is modified to provide summary of the issue, because of
>     which rate-limiting the bonding driver messages is needed.
> v2: https://lore.kernel.org/lkml/20240215172554.4211-1-praveen.kannoju@oracle.com/
>   - Use exising net_ratelimit() instead of introducing new rate-limit
>     parameter.
> v1: https://lore.kernel.org/lkml/20240214044245.33170-1-praveen.kannoju@oracle.com/
> ---
>  drivers/net/bonding/bond_main.c | 36 ++++++++++++++++++++----------------
>  1 file changed, 20 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 4e0600c..e92eba1 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2610,12 +2610,13 @@ static int bond_miimon_inspect(struct bonding *bond)
>  			commit++;
>  			slave->delay = bond->params.downdelay;
>  			if (slave->delay) {
> -				slave_info(bond->dev, slave->dev, "link status down for %sinterface, disabling it in %d ms\n",
> -					   (BOND_MODE(bond) ==
> -					    BOND_MODE_ACTIVEBACKUP) ?
> -					    (bond_is_active_slave(slave) ?
> -					     "active " : "backup ") : "",
> -					   bond->params.downdelay * bond->params.miimon);
> +				if (net_ratelimit())
> +					slave_info(bond->dev, slave->dev, "link status down for %sinterface, disabling it in %d ms\n",
> +						   (BOND_MODE(bond) ==
> +						   BOND_MODE_ACTIVEBACKUP) ?
> +						   (bond_is_active_slave(slave) ?
> +						   "active " : "backup ") : "",
> +						   bond->params.downdelay * bond->params.miimon);
>  			}

Hi Praveen,

As this is used several times I think that it would be worth introducing
a slave_info_ratelimit() helper. That is  assuming slave_info() is still used
without a rate limit. If not, you could just add net_ratelimit directly
to slave_info().

If none of this is desirable for some reason, then could you consider
reducing indentation somehow. f.e.:

		if (slave->delayi && net_ratelimit())
			slave_info(...