linux-kernel - Re: [PATCH] RDMA/rxe: Fix a couple IS

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Message-ID: <d72af2c1-2faf-46db-b212-0b800040c311@linux.dev>
Date: Wed, 25 Jun 2025 11:03:49 -0700
From: "yanjun.zhu" <yanjun.zhu@...ux.dev>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Zhu Yanjun <zyjzyj2000@...il.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
 Daisuke Matsuda <dskmtsd@...il.com>, linux-rdma@...r.kernel.org,
 linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] RDMA/rxe: Fix a couple IS_ERR() vs NULL bugs

On 6/25/25 8:22 AM, Dan Carpenter wrote:
> The lookup_mr() function returns NULL on error.  It never returns error
> pointers.

Yes, I agree with you. However, this commit is intended to fix an issue 
in the rdma-next tree. The corresponding repository is: 
https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git.

Therefore, the subject should be: [PATCH rdma-next]

This problem does not exist in the upstream Linux kernel.

Other than that, I have no issues with the commit.

Reviewed-by: Zhu Yanjun <yanjun.zhu@...ux.dev>

Zhu Yanjun

> 
> Fixes: 9284bc34c773 ("RDMA/rxe: Enable asynchronous prefetch for ODP MRs")
> Fixes: 3576b0df1588 ("RDMA/rxe: Implement synchronous prefetch for ODP MRs")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>   drivers/infiniband/sw/rxe/rxe_odp.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
> index 01a59d3f8ed4..f58e3ec6252f 100644
> --- a/drivers/infiniband/sw/rxe/rxe_odp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_odp.c
> @@ -470,10 +470,10 @@ static int rxe_ib_prefetch_sg_list(struct ib_pd *ibpd,
>   		mr = lookup_mr(pd, IB_ACCESS_LOCAL_WRITE,
>   			       sg_list[i].lkey, RXE_LOOKUP_LOCAL);
>   
> -		if (IS_ERR(mr)) {
> +		if (!mr) {
>   			rxe_dbg_pd(pd, "mr with lkey %x not found\n",
>   				   sg_list[i].lkey);
> -			return PTR_ERR(mr);
> +			return -EINVAL;
>   		}
>   
>   		if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH_WRITE &&
> @@ -535,8 +535,10 @@ static int rxe_ib_advise_mr_prefetch(struct ib_pd *ibpd,
>   		/* Takes a reference, which will be released in the queued work */
>   		mr = lookup_mr(pd, IB_ACCESS_LOCAL_WRITE,
>   			       sg_list[i].lkey, RXE_LOOKUP_LOCAL);
> -		if (IS_ERR(mr))
> +		if (!mr) {
> +			mr = ERR_PTR(-EINVAL);
>   			goto err;
> +		}
>   
>   		work->frags[i].io_virt = sg_list[i].addr;
>   		work->frags[i].length = sg_list[i].length;