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| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2008-01-25 20:57:41 +0300 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2008-01-31 00:22:27 +0300 |
| commit | b5d2a5e04e6a26cb3f77af8cbc31e74c361d706c (patch) | |
| tree | cfc3b2dc141f643bcf6ef065cca802340b335799 /drivers/firewire/fw-device.h | |
| parent | cf5a56ac8083dd04ffe8b9b2ec7895e9bcff44bc (diff) | |
| download | linux-b5d2a5e04e6a26cb3f77af8cbc31e74c361d706c.tar.xz | |
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 894d4a92a18e..0854fe2bc110 100644 --- a/drivers/firewire/fw-device.h +++ b/drivers/firewire/fw-device.h @@ -35,6 +35,18 @@ struct fw_attribute_group { struct attribute *attrs[11]; }; +/* + * Note, fw_device.generation always has to be read before fw_device.node_id. + * Use SMP memory barriers to ensure this. Otherwise requests will be sent + * to an outdated node_id if the generation was updated in the meantime due + * to a bus reset. + * + * Likewise, fw-core will take care to update .node_id before .generation so + * that whenever fw_device.generation is current WRT the actual bus generation, + * fw_device.node_id is guaranteed to be current too. + * + * The same applies to fw_device.card->node_id vs. fw_device.generation. + */ struct fw_device { atomic_t state; struct fw_node *node; |