Re: [PATCH] PPC64: lockfix for rtas error log

[David Gibson]

On Tue, Jun 29, 2004 at 05:50:07PM -0500, linas@xxxxxxxxxxxxxx wrote:
> 
> Paul,
> 
> Could you please apply the following path to the ameslab tree, and/or
> forward it to the main 2.6 kernel maintainers.
> 
> This patch moves the location of a lock in order to protect
> the contents of a buffer until it has been copied to its final
> destination. Prior to this, a race existed whereby the buffer
> could be filled even while it was being emptied.
> 
> Signed-off-by: Linas Vepstas <linas@xxxxxxxxx>

Hmm... I note that log_error() does nothing but call ppc_md.log_error,
and I can't see anywhere that that is set to be non-NULL...

> +++ arch/ppc64/kernel/rtas.c	2004-06-29 17:14:05.000000000 -0500
> @@ -134,9 +134,10 @@ log_rtas_error(void)
> 
>  	spin_lock_irqsave(&rtas.lock, s);
>  	rc = __log_rtas_error();
> -	spin_unlock_irqrestore(&rtas.lock, s);
> -	if (rc == 0)
> +	if (rc == 0) {
>  		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
> +	}
> +	spin_unlock_irqrestore(&rtas.lock, s);
>  }
> 
>  int
> @@ -193,12 +194,13 @@ rtas_call(int token, int nargs, int nret
>  			outputs[i] = rtas_args->rets[i+1];
>  	ret = (int)((nret > 0) ? rtas_args->rets[0] : 0);
> 
> +	if (logit) {
> +		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
> +	}
> +
>  	/* Gotta do something different here, use global lock for now... */
>  	spin_unlock_irqrestore(&rtas.lock, s);
> 
> -	if (logit)
> -		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
> -
>  	return ret;
>  }
> 


-- 
David Gibson			| For every complex problem there is a
david AT gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson
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