Re: [PATCHv1 1/1] IB/srp: fix invalid indirect_sg_entries parameter value

[Bart Van Assche <Bart.VanAssche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>]

On Tue, 2017-01-03 at 15:51 +0200, Max Gurtovoy wrote:
> From: Israel Rukshin <israelr@mellanox.com>
> 
> After setting indirect_sg_entries module_param to huge value (e.g 500,000),
> srp_alloc_req_data() fails to allocate indirect descriptors for the request
> ring (kmalloc fails). This commit enforces the maximum value of indirect_sg_entries
> to be SG_MAX_SEGMENTS as signified in module param description.
> 
> Signed-off-by: Israel Rukshin <israelr@mellanox.com>
> Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
> ---
>  drivers/infiniband/ulp/srp/ib_srp.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
> index 0f67cf9..ccdd2c2 100644
> --- a/drivers/infiniband/ulp/srp/ib_srp.c
> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> @@ -3676,6 +3676,7 @@ static struct srp_function_template ib_srp_transport_functions = {
>  static int __init srp_init_module(void)
>  {
>  	int ret;
> +	unsigned int max_indirect_sg_entries = SG_MAX_SEGMENTS;
>  
>  	if (srp_sg_tablesize) {
>  		pr_warn("srp_sg_tablesize is deprecated, please use cmd_sg_entries\n");
> @@ -3699,6 +3700,12 @@ static int __init srp_init_module(void)
>  		indirect_sg_entries = cmd_sg_entries;
>  	}
>  
> +	if (indirect_sg_entries > max_indirect_sg_entries) {
> +		pr_warn("Clamping indirect_sg_entries to %u\n",
> +			max_indirect_sg_entries);
> +		indirect_sg_entries = max_indirect_sg_entries;
> +	}
> +
>  	srp_remove_wq = create_workqueue("srp_remove");
>  	if (!srp_remove_wq) {
>  		ret = -ENOMEM;

Hello Max,

That's a good catch, but why has the max_indirect_sg_entries variable been
introduced? Can it be left out?

Thanks,

Bart.