RE: [PATCH] qla4xxx: Return -ENOMEM on memory allocation failure

[Elliott, Robert (Server Storage)]

> -----Original Message-----
> From: linux-scsi-owner@xxxxxxxxxxxxxxx [mailto:linux-scsi-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Himangi Saraogi
> Sent: Friday, 04 July, 2014 1:28 PM
> To: Vikas Chaudhary; iscsi-driver@xxxxxxxxxx; James E.J. Bottomley; linux-
> scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: julia.lawall@xxxxxxx
> Subject: [PATCH] qla4xxx: Return -ENOMEM on memory allocation failure
> 
> In this code, 0 is returned on memory allocation failure, even though
> other failures return -ENOMEM or other similar values.
> 
> A simplified version of the Coccinelle semantic match that finds this
> problem is as follows:
> 
> // <smpl>
> @@
> expression ret;
> expression x,e1,e2,e3;
> identifier alloc;
> @@
> 
> ret = 0
> ... when != ret = e1
> *x = alloc(...)
> ... when != ret = e2
> if (x == NULL) { ... when != ret = e3
>   return ret;
> }
> // </smpl>
> 
> Signed-off-by: Himangi Saraogi <himangi774@xxxxxxxxx>
> Acked-by: Julia Lawall <julia.lawall@xxxxxxx>
> ---
>  drivers/scsi/qla4xxx/ql4_os.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
> index c5d9564..72ba671 100644
> --- a/drivers/scsi/qla4xxx/ql4_os.c
> +++ b/drivers/scsi/qla4xxx/ql4_os.c
> @@ -1050,6 +1050,7 @@ static int qla4xxx_get_host_stats(struct Scsi_Host
> *shost, char *buf, int len)
>  	if (!ql_iscsi_stats) {
>  		ql4_printk(KERN_ERR, ha,
>  			   "Unable to allocate memory for iscsi stats\n");
> +		ret = -ENOMEM;
>  		goto exit_host_stats;
>  	}
> 

Also, the only caller of this function doesn't use the return 
value - it's overwritten by another function call:

drivers/scsi/scsi_transport_iscsi.c:
                err = transport->get_host_stats(shost, buf, host_stats_size);

                actual_size = nlmsg_total_size(sizeof(*ev) + host_stats_size);
                skb_trim(skbhost_stats, NLMSG_ALIGN(actual_size));
                nlhhost_stats->nlmsg_len = actual_size;

                err = iscsi_multicast_skb(skbhost_stats, ISCSI_NL_GRP_ISCSID,
                                          GFP_KERNEL);


---
Rob Elliott    HP Server Storage



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