[Devel] Re: [ckrm-tech] [PATCH 5/7] BC: user interface (syscalls)

[Chandra Seetharaman]

On Tue, 2006-08-29 at 18:55 +0400, Kirill Korotaev wrote:
> Add the following system calls for BC management:
>  1. sys_get_bcid     - get current BC id
>  2. sys_set_bcid     - change exec_ and fork_ BCs on current
>  3. sys_set_bclimit  - set limits for resources consumtions 
>  4. sys_get_bcstat   - return br_resource_parm on resource
> 
> Signed-off-by: Pavel Emelianov <xemul at sw.ru>
> Signed-off-by: Kirill Korotaev <dev at sw.ru>
> 
> ---
<snip>

> +
> +asmlinkage long sys_set_bclimit(bcid_t id, unsigned long resource,
> +		unsigned long __user *limits)
> +{
> +	int error;
> +	unsigned long flags;
> +	struct beancounter *bc;
> +	unsigned long new_limits[2];
> +
> +	error = -EPERM;
> +	if(!capable(CAP_SYS_RESOURCE))
> +		goto out;
> +
> +	error = -EINVAL;
> +	if (resource >= BC_RESOURCES)
> +		goto out;
> +
> +	error = -EFAULT;
> +	if (copy_from_user(&new_limits, limits, sizeof(new_limits)))
> +		goto out;
> +
> +	error = -EINVAL;
> +	if (new_limits[0] > BC_MAXVALUE || new_limits[1] > BC_MAXVALUE ||
> +			new_limits[0] > new_limits[1])
> +		goto out;
> +
> +	error = -ENOENT;
> +	bc = beancounter_findcreate(id, BC_LOOKUP);
> +	if (bc == NULL)
> +		goto out;

Moving this to be before copy_from_user() would be efficient.
> +
> +	spin_lock_irqsave(&bc->bc_lock, flags);
> +	bc->bc_parms[resource].barrier = new_limits[0];
> +	bc->bc_parms[resource].limit = new_limits[1];
> +	spin_unlock_irqrestore(&bc->bc_lock, flags);
> +
> +	put_beancounter(bc);
> +	error = 0;
> +out:
> +	return error;
> +}
<snip>
-- 

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    Chandra Seetharaman               | Be careful what you choose....
              - sekharan at us.ibm.com   |      .......you may get it.
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