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Re: [PATCH v2 5/7] xen/console: correct leaky-bucket rate limiter
- To: dmukhin@xxxxxxxx
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 19 Feb 2026 15:11:34 +0100
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- Cc: andrew.cooper3@xxxxxxxxxx, anthony.perard@xxxxxxxxxx, julien@xxxxxxx, michal.orzel@xxxxxxx, roger.pau@xxxxxxxxxx, sstabellini@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 19 Feb 2026 14:11:47 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 06.02.2026 21:24, dmukhin@xxxxxxxx wrote:
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -1291,21 +1291,27 @@ static bool do_printk_ratelimit(unsigned int
> ratelimit_ms,
> unsigned int ratelimit_burst)
> {
> static DEFINE_SPINLOCK(ratelimit_lock);
> - static unsigned long toks = 10 * 5 * 1000;
> + static unsigned long toks;
> static unsigned long last_msg;
> static unsigned int missed;
> unsigned long flags;
> - unsigned long long now = NOW(); /* ns */
> + unsigned long long now;
> unsigned long ms;
>
> + if ( !printk_ratelimit_burst || !printk_ratelimit_burst )
> + return true;
> +
> + if ( !toks )
> + toks = printk_ratelimit_burst * printk_ratelimit_ms;
Btw, instead of this I wonder whether it wouldn't be neater to use the nested
functions extension of the compiler:
void __constructor __init init(void)
{
toks = printk_ratelimit_burst * printk_ratelimit_ms;
}
If we wanted this, we'd need to record the extension use in
docs/misra/C-language-toolchain.rst, though. Plus init_constructors() would
need invoking _far_ earlier (perhaps right after command line parsing).
Jan
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