Re: [PATCH 2.6.11.2][RFC] printk with anti-cluttering-feature

[Bodo Eggert]

On Sun, 20 Mar 2005, Michael Tokarev wrote:
> Bodo Eggert wrote:

> > (please CC me on reply)
> > 
> > Issue:
> > 
> > On some conditions, the dmesg is spammed with repeated warnings about the
> > same issue which is neither critical nor going to be fixed. This may
> > result in losing the boot messages or missing other important messages.
> 
> There's printk_ratelimit() already, used in quite several places in kernel
> (or net_ratelimit() for net/* stuff).  See also Documentation/sysctl/kernel.txt,
> search for printk_ratelimit.  JFYI.

ACK, but that's designed to work against a DoS, not against cluttering the 
log. The messages I want to suppress are low-frequent.

I now realize that some of these warnings may be triggered by userspace, 
and since userspace-triggered warnings are a possible DoS, these parts of 
code should be rate-limited, too. I think it's best to include a 
rate-limit check in my printk_nospam to make it work against slow log 
spamming _and_ DoS.

-- 
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