diff options
author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2008-01-25 12:57:41 -0500 |
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committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2008-01-30 16:22:27 -0500 |
commit | b5d2a5e04e6a26cb3f77af8cbc31e74c361d706c (patch) | |
tree | cfc3b2dc141f643bcf6ef065cca802340b335799 /drivers/firewire/fw-device.h | |
parent | cf5a56ac8083dd04ffe8b9b2ec7895e9bcff44bc (diff) |
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>
Diffstat (limited to 'drivers/firewire/fw-device.h')
-rw-r--r-- | drivers/firewire/fw-device.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h index 894d4a92a18..0854fe2bc11 100644 --- a/drivers/firewire/fw-device.h +++ b/drivers/firewire/fw-device.h | |||
@@ -35,6 +35,18 @@ struct fw_attribute_group { | |||
35 | struct attribute *attrs[11]; | 35 | struct attribute *attrs[11]; |
36 | }; | 36 | }; |
37 | 37 | ||
38 | /* | ||
39 | * Note, fw_device.generation always has to be read before fw_device.node_id. | ||
40 | * Use SMP memory barriers to ensure this. Otherwise requests will be sent | ||
41 | * to an outdated node_id if the generation was updated in the meantime due | ||
42 | * to a bus reset. | ||
43 | * | ||
44 | * Likewise, fw-core will take care to update .node_id before .generation so | ||
45 | * that whenever fw_device.generation is current WRT the actual bus generation, | ||
46 | * fw_device.node_id is guaranteed to be current too. | ||
47 | * | ||
48 | * The same applies to fw_device.card->node_id vs. fw_device.generation. | ||
49 | */ | ||
38 | struct fw_device { | 50 | struct fw_device { |
39 | atomic_t state; | 51 | atomic_t state; |
40 | struct fw_node *node; | 52 | struct fw_node *node; |