linux-kernel - Re: [PATCH RFC] iw_cxgb4: drop check

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Date:   Wed, 23 Jan 2019 11:30:08 -0700
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Nicholas Mc Guire <hofrat@...dl.org>
Cc:     Steve Wise <swise@...lsio.com>, Doug Ledford <dledford@...hat.com>,
        Raju Rangoju <rajur@...lsio.com>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] iw_cxgb4: drop check - dead code

On Sun, Jan 20, 2019 at 02:27:13AM +0100, Nicholas Mc Guire wrote:
> The kmalloc is called with  | __GFP_NOFAIL  so there is no point in
> checking the return value - it either returns valid storage or it would
> hang/terminate there. But it is not possible to say if the use of
> __GFP_NOFAIL is really needed and the check should be removed or
> vice-versa (use of __GFP_NOFAIL should be only in exceptional
> cases as I understand it and alloc_srq_queue() is called in quite
> a few places)
> In either way it would need fixing.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> Fixes: 6a0b6174d35a ("rdma/cxgb4: Add support for kernel mode SRQ's")
> ---

Steve? It seems weird to have NOFAIL and then have an error unwind
path, what is the deal here?

> diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
> index 917ce5c..c2a12ba 100644
> --- a/drivers/infiniband/hw/cxgb4/qp.c
> +++ b/drivers/infiniband/hw/cxgb4/qp.c
> @@ -2597,8 +2597,6 @@ static int alloc_srq_queue(struct c4iw_srq *srq, struct c4iw_dev_ucontext *uctx,
>  	wr_len = sizeof(*res_wr) + sizeof(*res);
>  
>  	skb = alloc_skb(wr_len, GFP_KERNEL | __GFP_NOFAIL);
> -	if (!skb)
> -		goto err_free_queue;
>  	set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0);
>  
>  	res_wr = (struct fw_ri_res_wr *)__skb_put(skb, wr_len);
> -- 
> 2.1.4
>