ieee1394: sbp2: fix race condition in state change

An intermediate transition from _RUNNING to _IN_SHUTDOWN could have been
missed by the former code.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c
index 3f5dbcb..a373c18 100644 (file)
--- a/drivers/ieee1394/sbp2.c
+++ b/drivers/ieee1394/sbp2.c
@@ -895,12 +895,13 @@ static void sbp2_host_reset(struct hpsb_host *host)
                return;
 
        read_lock_irqsave(&sbp2_hi_logical_units_lock, flags);
+
        list_for_each_entry(lu, &hi->logical_units, lu_list)
-               if (likely(atomic_read(&lu->state) !=
-                          SBP2LU_STATE_IN_SHUTDOWN)) {
-                       atomic_set(&lu->state, SBP2LU_STATE_IN_RESET);
+               if (atomic_cmpxchg(&lu->state,
+                                  SBP2LU_STATE_RUNNING, SBP2LU_STATE_IN_RESET)
+                   == SBP2LU_STATE_RUNNING)
                        scsi_block_requests(lu->shost);
-               }
+
        read_unlock_irqrestore(&sbp2_hi_logical_units_lock, flags);
 }