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

[Don Brace <brace77070@xxxxxxxxx>]

On 10/26/2015 09:55 AM, Tomas Henzl wrote:
> 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@xxxxxxxx>
> > ---
> >   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)
I wanted to reschedule the scan to see what happened after
a reset.

There also seems to be some raciness between the reset
handler and the re-scan procedure.

> Btw. why is an atomic variable needed here?
Overkill. I can change reset_in_progress to an int.

> --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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