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Subject[PATCH] 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>
---
drivers/ieee1394/sbp2.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
Index: linux/drivers/ieee1394/sbp2.c
===================================================================
--- linux.orig/drivers/ieee1394/sbp2.c
+++ linux/drivers/ieee1394/sbp2.c
@@ -895,12 +895,13 @@ static void sbp2_host_reset(struct hpsb_
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);
}

--
Stefan Richter
-=====-==--- =-== ===-=
http://arcgraph.de/sr/


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