Re: [PATCH 2/2] libata: Fix NULL pointer of scsi_host in ata_port

[Peter Hurley <peter@hurleysoftware.com>]

[ +cc Jesse Brandeburg - similar LKML report (but on x86_64) ]

On 07/22/2014 10:51 AM, Mike Qiu wrote:
> In ata_sas_port_alloc(), it haven't initialized scsi_host field in
> ata_port, although scsi_host is in parameters list and unused in this
> function.
> 
> With commit 1871ee134b73 ("libata: support the ata host which implements a queue depth less than 32")
> ata_qc_new() try to use scsi_host, while it
> is a NULL pointer for ipr IOA and error message shows below:
> 
> Unable to handle kernel paging request for data at address 0x00000114
> Faulting instruction address: 0xc0000000005c2580
> Oops: Kernel access of bad area, sig: 11 [#1]
> ...
> NIP [c0000000005c2580] .ata_qc_new_init+0x30/0x1f0
> LR [c0000000005c9384] .ata_scsi_translate+0x44/0x230
> Call Trace:
> 0xc0000003ad332280 (unreliable)
> .ata_scsi_translate+0x44/0x230
> .ipr_queuecommand+0x2e0/0x780 [ipr]
> .scsi_dispatch_cmd+0xec/0x400
> .scsi_request_fn+0x52c/0x670
> .__blk_run_queue+0x5c/0x80
> .blk_execute_rq_nowait+0xf8/0x1c0
> .blk_execute_rq+0x88/0x150
> .scsi_execute+0xf0/0x1f0
> .scsi_execute_req_flags+0xc4/0x170
> .scsi_probe_and_add_lun+0x2d4/0xe00
> .__scsi_scan_target+0x1a4/0x790
> .scsi_scan_channel.part.3+0x80/0xc0
> .scsi_scan_host_selected+0x1a0/0x240
> .do_scan_async+0x30/0x210
> .async_run_entry_fn+0x78/0x1c0
> .process_one_work+0x1c4/0x4a0
> .worker_thread+0x184/0x600
> .kthread+0x10c/0x130
> .ret_from_kernel_thread+0x58/0x7c
> 
> While scsi_host is unused in ata_sas_port_alloc(), better to set it
> in ata_sas_port_alloc() instead of in driver.
> 
> Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> ---
>  drivers/ata/libata-scsi.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 0586f66..a472b6f 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -4070,6 +4070,7 @@ struct ata_port *ata_sas_port_alloc(struct ata_host *host,
>  	ap->flags |= port_info->flags;
>  	ap->ops = port_info->port_ops;
>  	ap->cbl = ATA_CBL_SATA;
> +	ap->scsi_host = shost;
>  
>  	return ap;
>  }
>