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authorStefan Richter <stefanr@s5r6.in-berlin.de>2008-01-25 18:57:41 +0100
committerStefan Richter <stefanr@s5r6.in-berlin.de>2008-01-30 22:22:27 +0100
commitb5d2a5e04e6a26cb3f77af8cbc31e74c361d706c (patch)
treecfc3b2dc141f643bcf6ef065cca802340b335799 /drivers/firewire/fw-device.c
parentcf5a56ac8083dd04ffe8b9b2ec7895e9bcff44bc (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.c')
-rw-r--r--drivers/firewire/fw-device.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index 56681b3b297b..872df2238609 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -27,6 +27,7 @@
#include <linux/idr.h>
#include <linux/rwsem.h>
#include <asm/semaphore.h>
+#include <asm/system.h>
#include <linux/ctype.h>
#include "fw-transaction.h"
#include "fw-topology.h"
@@ -182,9 +183,14 @@ static void fw_device_release(struct device *dev)
int fw_device_enable_phys_dma(struct fw_device *device)
{
+ int generation = device->generation;
+
+ /* device->node_id, accessed below, must not be older than generation */
+ smp_rmb();
+
return device->card->driver->enable_phys_dma(device->card,
device->node_id,
- device->generation);
+ generation);
}
EXPORT_SYMBOL(fw_device_enable_phys_dma);
@@ -389,12 +395,16 @@ static int read_rom(struct fw_device *device, int index, u32 * data)
struct read_quadlet_callback_data callback_data;
struct fw_transaction t;
u64 offset;
+ int generation = device->generation;
+
+ /* device->node_id, accessed below, must not be older than generation */
+ smp_rmb();
init_completion(&callback_data.done);
offset = 0xfffff0000400ULL + index * 4;
fw_send_request(device->card, &t, TCODE_READ_QUADLET_REQUEST,
- device->node_id, device->generation, device->max_speed,
+ device->node_id, generation, device->max_speed,
offset, NULL, 4, complete_transaction, &callback_data);
wait_for_completion(&callback_data.done);
@@ -801,6 +811,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
device = node->data;
device->node_id = node->node_id;
+ smp_wmb(); /* update node_id before generation */
device->generation = card->generation;
if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
PREPARE_DELAYED_WORK(&device->work, fw_device_update);