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

[Don Brace]

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.br...@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)

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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