hvc console sleep under spinlock

[Anton Blanchard]

Hi Nathan,

> Thanks, patch has been updated accordingly.

Looks good. I just had a thought, is there an uppoer limit on count?
(eg what happens when someone does a 1MB write()?)

> Could this be pushed to mainline through Ameslab, or should it be taken
> to lkml?  I ask because the hvc code is not in an arch-specific location
> in the source tree.

These sort of things usually get pushed separately but with the 2.6
lockdown we may not get it in until after 2.6.0.

Anton

> diff -Nru a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
> --- a/drivers/char/hvc_console.c	Mon Nov  3 19:10:06 2003
> +++ b/drivers/char/hvc_console.c	Mon Nov  3 19:10:06 2003
> @@ -130,24 +130,26 @@
>  		     const unsigned char *buf, int count)
>  {
>  	struct hvc_struct *hp = tty->driver_data;
> -	char *p;
> +	char *p, *kbuf = NULL;
>  	int todo, written = 0;
>  	unsigned long flags;
>
> +	if (from_user) {
> +		kbuf = kmalloc(count, GFP_KERNEL);
> +		if (!kbuf)
> +			return -ENOMEM;
> +		if (copy_from_user(kbuf, buf, count)) {
> +			kfree(kbuf);
> +			return -EFAULT;
> +		}
> +		buf = kbuf;
> +	}
>  	spin_lock_irqsave(&hp->lock, flags);
>  	while (count > 0 && (todo = N_OUTBUF - hp->n_outbuf) > 0) {
>  		if (todo > count)
>  			todo = count;
>  		p = hp->outbuf + hp->n_outbuf;
> -		if (from_user) {
> -			todo -= copy_from_user(p, buf, todo);
> -			if (todo == 0) {
> -				if (written == 0)
> -					written = -EFAULT;
> -				break;
> -			}
> -		} else
> -			memcpy(p, buf, todo);
> +		memcpy(p, buf, todo);
>  		count -= todo;
>  		buf += todo;
>  		hp->n_outbuf += todo;
> @@ -155,7 +157,7 @@
>  		hvc_push(hp);
>  	}
>  	spin_unlock_irqrestore(&hp->lock, flags);
> -
> +	kfree(kbuf);
>  	return written;
>  }
>


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