firewire: enforce access order between generation and node ID, fix "giving up on config rom"
fw_device.node_id and fw_device.generation are accessed without mutexes.
We have to ensure that all readers will get to see node_id updates
before generation updates.
Fixes an inability to recognize devices after "giving up on config rom",
https://bugzilla.redhat.com/show_bug.cgi?id=429950
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Reviewed by Nick Piggin <nickpiggin@yahoo.com.au>.
Verified to fix 'giving up on config rom' issues on multiple system and
drive combinations that were previously affected.
Signed-off-by: Jarod Wilson <jwilson@redhat.com>
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
diff --git a/drivers/firewire/fw-topology.c b/drivers/firewire/fw-topology.c
index 0fc9b00..172c186 100644
--- a/drivers/firewire/fw-topology.c
+++ b/drivers/firewire/fw-topology.c
@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/errno.h>
+#include <asm/system.h>
#include "fw-transaction.h"
#include "fw-topology.h"
@@ -518,6 +519,11 @@
card->bm_retries = 0;
card->node_id = node_id;
+ /*
+ * Update node_id before generation to prevent anybody from using
+ * a stale node_id together with a current generation.
+ */
+ smp_wmb();
card->generation = generation;
card->reset_jiffies = jiffies;
schedule_delayed_work(&card->work, 0);