linux-kernel - Re: [PATCH] IB/srpt: Fix passing zero to 'PTR

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Message-ID: <c73d9be0-0bd8-634a-e3d1-c81fe4c30482@acm.org>
Date:   Thu, 12 Nov 2020 10:25:48 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     Jason Gunthorpe <jgg@...dia.com>,
        YueHaibing <yuehaibing@...wei.com>
Cc:     dledford@...hat.com, linux-rdma@...r.kernel.org,
        target-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] IB/srpt: Fix passing zero to 'PTR_ERR'

On 11/12/20 9:20 AM, Jason Gunthorpe wrote:
> I think it should be like this, Bart?
> 
> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
> index 6017d525084a0c..80f9673956ced2 100644
> --- a/drivers/infiniband/ulp/srpt/ib_srpt.c
> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
> @@ -2311,7 +2311,7 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>   
>   	mutex_lock(&sport->port_guid_id.mutex);
>   	list_for_each_entry(stpg, &sport->port_guid_id.tpg_list, entry) {
> -		if (!IS_ERR_OR_NULL(ch->sess))
> +		if (ch->sess)
>   			break;
>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
>   						tag_size, TARGET_PROT_NORMAL,
> @@ -2321,12 +2321,12 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>   
>   	mutex_lock(&sport->port_gid_id.mutex);
>   	list_for_each_entry(stpg, &sport->port_gid_id.tpg_list, entry) {
> -		if (!IS_ERR_OR_NULL(ch->sess))
> +		if (ch->sess)
>   			break;
>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
>   					tag_size, TARGET_PROT_NORMAL, i_port_id,
>   					ch, NULL);
> -		if (!IS_ERR_OR_NULL(ch->sess))
> +		if (ch->sess)
>   			break;
>   		/* Retry without leading "0x" */
>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
> @@ -2335,7 +2335,9 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>   	}
>   	mutex_unlock(&sport->port_gid_id.mutex);
>   
> -	if (IS_ERR_OR_NULL(ch->sess)) {
> +	if (!ch->sess)
> +		ch->sess = ERR_PTR(-ENOENT);
> +	if (IS_ERR(ch->sess)) {
>   		WARN_ON_ONCE(ch->sess == NULL);
>   		ret = PTR_ERR(ch->sess);
>   		ch->sess = NULL;
> 

Hi Jason,

The ib_srpt driver accepts three different formats for the initiator 
ACL. Up to two of the three target_setup_session() calls will fail if 
the fifth argument of target_setup_session() does not use the format of 
the initiator ID in configfs. If the first or the second 
target_setup_session() call fails it is essential that later 
target_setup_session() calls happen. Hence the IS_ERR_OR_NULL(ch->sess) 
checks in the above loops.

In other words, I like YueHaibing's patch better.

Thanks,

Bart.