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>

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 9c9627e..cf6083a 100644 (file)
--- 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: