linux-kernel - Re: [PATCH 6/6] kmod: use simplified rate limit printk

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Date:   Fri, 19 May 2017 15:23:27 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     shuah@...nel.org, jeyu@...hat.com, rusty@...tcorp.com.au,
        ebiederm@...ssion.com, acme@...hat.com, corbet@....net,
        martin.wilck@...e.com, mmarek@...e.com, pmladek@...e.com,
        hare@...e.com, rwright@....com, jeffm@...e.com, DSterba@...e.com,
        fdmanana@...e.com, neilb@...e.com, linux@...ck-us.net,
        rgoldwyn@...e.com, subashab@...eaurora.org, xypron.glpk@....de,
        keescook@...omium.org, atomlin@...hat.com, mbenes@...e.cz,
        paulmck@...ux.vnet.ibm.com, dan.j.williams@...el.com,
        jpoimboe@...hat.com, davem@...emloft.net, mingo@...hat.com,
        akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
        gregkh@...uxfoundation.org, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] kmod: use simplified rate limit printk

On Thu, May 18, 2017 at 08:24:44PM -0700, Luis R. Rodriguez wrote:
> Just use the simplified rate limit printk when the max modprobe
> limit is reached, while at it throw out a bone should the error
> be triggered.
> 
> Reviewed-by: Petr Mladek <pmladek@...e.com>
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
> ---
>  kernel/kmod.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/kernel/kmod.c b/kernel/kmod.c
> index 7ea11dbc7564..56cd2a16e7ac 100644
> --- a/kernel/kmod.c
> +++ b/kernel/kmod.c
> @@ -166,7 +166,6 @@ int __request_module(bool wait, const char *fmt, ...)
>  	va_list args;
>  	char module_name[MODULE_NAME_LEN];
>  	int ret;
> -	static int kmod_loop_msg;
>  
>  	/*
>  	 * We don't allow synchronous module loading from async.  Module
> @@ -191,13 +190,8 @@ int __request_module(bool wait, const char *fmt, ...)
>  
>  	ret = kmod_umh_threads_get();
>  	if (ret) {
> -		/* We may be blaming an innocent here, but unlikely */
> -		if (kmod_loop_msg < 5) {
> -			printk(KERN_ERR
> -			       "request_module: runaway loop modprobe %s\n",
> -			       module_name);
> -			kmod_loop_msg++;
> -		}
> +		pr_err_ratelimited("%s: module \"%s\" reached limit (%u) of concurrent modprobe calls\n",
> +				   __func__, module_name, max_modprobes);

This is completely different behavior, isn't it? Instead of reporting
first 5 occurrences we now reporting every once in a while. Why is this
new behavior better?

-- 
Dmitry