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firewire: enforce access order between generation and node ID, fix "giving up on config rom"

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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>
This commit is contained in:
Stefan Richter
2008-01-25 18:57:41 +01:00
parent cf5a56ac80
commit b5d2a5e04e
5 changed files with 35 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/firewire/fw-device.c
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@ -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);