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-rw-r--r--drivers/block/cciss.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 42eaddb54380..bf2d1c80b788 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -3416,8 +3416,22 @@ static int check_for_unit_attention(ctlr_info_t *h, CommandList_struct *c)
case REPORT_LUNS_CHANGED:
printk(KERN_WARNING "cciss%d: report LUN data "
"changed\n", h->ctlr);
- add_to_scan_list(h);
- wake_up_process(cciss_scan_thread);
+ /*
+ * Here, we could call add_to_scan_list and wake up the scan thread,
+ * except that it's quite likely that we will get more than one
+ * REPORT_LUNS_CHANGED condition in quick succession, which means
+ * that those which occur after the first one will likely happen
+ * *during* the scan_thread's rescan. And the rescan code is not
+ * robust enough to restart in the middle, undoing what it has already
+ * done, and it's not clear that it's even possible to do this, since
+ * part of what it does is notify the block layer, which starts
+ * doing it's own i/o to read partition tables and so on, and the
+ * driver doesn't have visibility to know what might need undoing.
+ * In any event, if possible, it is horribly complicated to get right
+ * so we just don't do it for now.
+ *
+ * Note: this REPORT_LUNS_CHANGED condition only occurs on the MSA2012.
+ */
return 1;
break;
case POWER_OR_RESET: