Commit b5d2a5e0 authored by Stefan Richter's avatar Stefan Richter

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=429950Signed-off-by: default avatarStefan 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: default avatarJarod Wilson <jwilson@redhat.com>
Signed-off-by: default avatarKristian Høgsberg <krh@redhat.com>
parent cf5a56ac
......@@ -207,6 +207,7 @@ fill_bus_reset_event(struct fw_cdev_event_bus_reset *event,
event->closure = client->bus_reset_closure;
event->type = FW_CDEV_EVENT_BUS_RESET;
event->generation = client->device->generation;
smp_rmb(); /* node_id must not be older than generation */
event->node_id = client->device->node_id;
event->local_node_id = card->local_node->node_id;
event->bm_node_id = 0; /* FIXME: We don't track the BM. */
......
......@@ -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);
......
......@@ -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;
......
......@@ -40,6 +40,7 @@
#include <linux/stringify.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <asm/system.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
......@@ -662,6 +663,7 @@ static void sbp2_login(struct work_struct *work)
int generation, node_id, local_node_id;
generation = device->generation;
smp_rmb(); /* node_id must not be older than generation */
node_id = device->node_id;
local_node_id = device->card->node_id;
......@@ -912,6 +914,7 @@ static void sbp2_reconnect(struct work_struct *work)
int generation, node_id, local_node_id;
generation = device->generation;
smp_rmb(); /* node_id must not be older than generation */
node_id = device->node_id;
local_node_id = device->card->node_id;
......
......@@ -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 @@ fw_core_handle_bus_reset(struct fw_card *card,
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);
......
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