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Subject: Re: [PATCH v3 6/7] libsas: add wait-complete support to sync
 discovery event
To: Yijing Wang <wangyijing@huawei.com>, <jejb@linux.vnet.ibm.com>,
        <martin.petersen@oracle.com>
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From: John Garry <john.garry@huawei.com>
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Date: Wed, 12 Jul 2017 14:51:59 +0100
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On 10/07/2017 08:06, Yijing Wang wrote:
>
>  static void sas_chain_event(int event, unsigned long *pending,
> @@ -592,9 +596,9 @@ int sas_discover_event(struct asd_sas_port *port, enum discover_event ev)
>  {
>  	struct sas_discovery *disc;
>
> +	disc = &port->disc;
>  	if (!port)
>  		return 0;
> -	disc = &port->disc;
>
>  	BUG_ON(ev >= DISC_NUM_EVENTS);
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 570b2cb..9d26c28 1

I was just looking through the code and I noticed this, above. Is there 
a specific reason to move the NULL check, or was it modified accidentally?

I mean, if port is NULL I don't think we would get as far as checking it 
as we would have already de-referenced it.