linux-kernel - Re: [PATCH] irqbalance, powerpc: add IRQs without settable SMP affinity to banned list

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Date:	Thu, 23 Sep 2010 18:22:39 +1000
From:	Michael Ellerman <michael@...erman.id.au>
To:	Michael Neuling <mikey@...ling.org>
Cc:	Arjen Van De Ven <arjanvandeven@...il.com>,
	Neil Horman <nhorman@...il.com>, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] irqbalance, powerpc: add IRQs without settable SMP
 affinity to banned list

On Wed, 2010-09-22 at 16:04 +1000, Michael Neuling wrote:
> When irqblance attempts writes to the IPI smp_affinity (ie.
> /proc/irq/16/smp_affinity in the above example) it fails but irqbalance
> ignores currently ignores this.
> 
> This patch catches these write fails and in this case adds that IRQ
> number to the banned IRQ list.  This will catch the above IPI case and
> any other IRQ where the SMP affinity can't be set.

Cool!

> Index: irqbalance/irqlist.c
> ===================================================================
> --- irqbalance.orig/irqlist.c
> +++ irqbalance/irqlist.c
> @@ -67,7 +67,7 @@
>  	DIR *dir;
>  	struct dirent *entry;
>  	char *c, *c2;
> -	int nr , count = 0;
> +	int nr , count = 0, can_set = 1;
>  	char buf[PATH_MAX];
>  	sprintf(buf, "/proc/irq/%i", number);
>  	dir = opendir(buf);
> @@ -80,7 +80,7 @@
>  			size_t size = 0;
>  			FILE *file;
>  			sprintf(buf, "/proc/irq/%i/smp_affinity", number);
> -			file = fopen(buf, "r");
> +			file = fopen(buf, "r+");
>  			if (!file)
>  				continue;
>  			if (getline(&line, &size, file)==0) {
> @@ -89,7 +89,14 @@
>  				continue;
>  			}
>  			cpumask_parse_user(line, strlen(line), irq->mask);
> -			fclose(file);
> +			/*
> +			 * Check that we can write the affinity, if
> +			 * not take it out of the list.
> +			 */
> +			if (fwrite(line, strlen(line) - 1, 1, file) == 0)

if (fputs(line, file) == EOF)

?

cheers


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