Re: [PATCH 05/21] hpsa: fix hpsa_adjust_hpsa_scsi_table

[Tomas Henzl <thenzl@redhat.com>]

On 24.10.2015 21:52, Don Brace wrote:
> Fix a NULL pointer issue in the driver when devices are removed
> during a reset.
>
> Signed-off-by: Don Brace <don.brace@pmcs.com>
> ---
>  drivers/block/cciss.h |    1 +
>  drivers/scsi/hpsa.c   |   16 ++++++++++++++++
>  drivers/scsi/hpsa.h   |    1 +
>  3 files changed, 18 insertions(+)
>
> diff --git a/drivers/block/cciss.h b/drivers/block/cciss.h
> index 7fda30e..036fb0f 100644
> --- a/drivers/block/cciss.h
> +++ b/drivers/block/cciss.h
> @@ -155,6 +155,7 @@ struct ctlr_info
>  	size_t reply_pool_size;
>  	unsigned char reply_pool_wraparound;
>  	u32 *blockFetchTable;
> +	atomic_t reset_in_progress;
>  };
>  
>  /*  Defining the diffent access_methods
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 3520d75..714bb76 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -1656,6 +1656,11 @@ static void adjust_hpsa_scsi_table(struct ctlr_info *h, int hostno,
>  	int nadded, nremoved;
>  	struct Scsi_Host *sh = NULL;
>  
> +	if (atomic_read(&h->reset_in_progress)) {
> +		h->drv_req_rescan = 1;
> +		return;
> +	}

Is it safe, what happens when a reset is invoked at this point?
Is it possible to somehow reuse the scan_lock or scan_finished
and change the logic and wait with the reset?
(maybe break and reschedule the scan)

Btw. why is an atomic variable needed here?

--tm


> +
>  	added = kzalloc(sizeof(*added) * HPSA_MAX_DEVICES, GFP_KERNEL);
>  	removed = kzalloc(sizeof(*removed) * HPSA_MAX_DEVICES, GFP_KERNEL);
>  
> @@ -1764,8 +1769,14 @@ static void adjust_hpsa_scsi_table(struct ctlr_info *h, int hostno,
>  		goto free_and_out;
>  
>  	sh = h->scsi_host;
> +	if (sh == NULL) {
> +		dev_warn(&h->pdev->dev, "%s: scsi_host is null\n", __func__);
> +		return;
> +	}
>  	/* Notify scsi mid layer of any removed devices */
>  	for (i = 0; i < nremoved; i++) {
> +		if (!removed[i])
> +			continue;
>  		if (removed[i]->expose_state & HPSA_SCSI_ADD) {
>  			struct scsi_device *sdev =
>  				scsi_device_lookup(sh, removed[i]->bus,
> @@ -1790,6 +1801,8 @@ static void adjust_hpsa_scsi_table(struct ctlr_info *h, int hostno,
>  
>  	/* Notify scsi mid layer of any added devices */
>  	for (i = 0; i < nadded; i++) {
> +		if (!added[i])
> +			continue;
>  		if (!(added[i]->expose_state & HPSA_SCSI_ADD))
>  			continue;
>  		if (scsi_add_device(sh, added[i]->bus,
> @@ -5227,12 +5240,15 @@ static int hpsa_eh_device_reset_handler(struct scsi_cmnd *scsicmd)
>  
>  	hpsa_show_dev_msg(__stringify(KERN_WARNING), h, dev, "resetting");
>  
> +	atomic_set(&h->reset_in_progress, 1);
> +
>  	/* send a reset to the SCSI LUN which the command was sent to */
>  	rc = hpsa_do_reset(h, dev, dev->scsi3addr, HPSA_RESET_TYPE_LUN,
>  			   DEFAULT_REPLY_QUEUE);
>  	snprintf(msg, sizeof(msg), "reset %s",
>  		 rc == 0 ? "completed successfully" : "failed");
>  	hpsa_show_dev_msg(__stringify(KERN_WARNING), h, dev, msg);
> +	atomic_set(&h->reset_in_progress, 0);
>  	return rc == 0 ? SUCCESS : FAILED;
>  }
>  
> diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
> index 642c8ce..c7c1697 100644
> --- a/drivers/scsi/hpsa.h
> +++ b/drivers/scsi/hpsa.h
> @@ -271,6 +271,7 @@ struct ctlr_info {
>  	wait_queue_head_t abort_cmd_wait_queue;
>  	wait_queue_head_t event_sync_wait_queue;
>  	struct mutex reset_mutex;
> +	atomic_t reset_in_progress;
>  };
>  
>  struct offline_device_entry {
>
> --
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