cciss: Fix race between disk-adding code and interrupt handler

Fix race condition between cciss_init_one(), cciss_update_drive_info(),
and cciss_check_queues().

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 9c9627e8e334..cf6083a1f928 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -1349,6 +1349,10 @@ static void cciss_update_drive_info(int ctlr, int drv_index)
                 spin_lock_irqsave(CCISS_LOCK(h->ctlr), flags);
                 h->drv[drv_index].busy_configuring = 1;
                 spin_unlock_irqrestore(CCISS_LOCK(h->ctlr), flags);
+
+                /* deregister_disk sets h->drv[drv_index].queue = NULL */
+                /* which keeps the interrupt handler from starting */
+                /* the queue. */
                 ret = deregister_disk(h->gendisk[drv_index],
                                       &h->drv[drv_index], 0);
                 h->drv[drv_index].busy_configuring = 0;
@@ -1419,6 +1423,10 @@ geo_inq:
                 blk_queue_hardsect_size(disk->queue,
                                         hba[ctlr]->drv[drv_index].block_size);
 
+                /* Make sure all queue data is written out before */
+                /* setting h->drv[drv_index].queue, as setting this */
+                /* allows the interrupt handler to start the queue */
+                wmb();
                 h->drv[drv_index].queue = disk->queue;
                 add_disk(disk);
         }
@@ -3520,10 +3528,17 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
                         continue;
                 blk_queue_hardsect_size(q, drv->block_size);
                 set_capacity(disk, drv->nr_blocks);
-                add_disk(disk);
                 j++;
         } while (j <= hba[i]->highest_lun);
 
+        /* Make sure all queue data is written out before */
+        /* interrupt handler, triggered by add_disk,  */
+        /* is allowed to start them. */
+        wmb();
+
+        for (j = 0; j <= hba[i]->highest_lun; j++)
+                add_disk(hba[i]->gendisk[j]);
+
         return 1;
 
       clean4: