lkml.org 
[lkml]   [2007]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] firewire: fw-core: enforce write order when updating fw_device.generation
Date
On Thursday 01 November 2007 12:49, Stefan Richter wrote:
> 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.
>

Hi, a few points:

- can change it to use spinlocks instead? This would be most
preferable.

- if not, you need comments.

- you also seem to be missing rmb()s now. I see a couple in the
firewire directory, but nothing that seems to be ordering loads
of these particular fields.

- use smp_*mb() if you are just ordering regular cacheable RAM
accesses.

Also, diffstat is a bit wrong... maybe you posted the wrong version?

> Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
> ---
> drivers/firewire/fw-device.c | 6 ++++++
> drivers/firewire/fw-topology.c | 1 +
> 2 files changed, 7 insertions(+)
>
> Index: linux/drivers/firewire/fw-device.c
> ===================================================================
> --- linux.orig/drivers/firewire/fw-device.c
> +++ linux/drivers/firewire/fw-device.c
> @@ -808,6 +813,7 @@ void fw_node_event(struct fw_card *card,
>
> device = node->data;
> device->node_id = node->node_id;
> + wmb();
> device->generation = card->generation;
> if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
> PREPARE_DELAYED_WORK(&device->work, fw_device_update);
> Index: linux/drivers/firewire/fw-topology.c
> ===================================================================
> --- linux.orig/drivers/firewire/fw-topology.c
> +++ linux/drivers/firewire/fw-topology.c
> @@ -518,6 +518,7 @@ fw_core_handle_bus_reset(struct fw_card
> card->bm_retries = 0;
>
> card->node_id = node_id;
> + wmb();
> card->generation = generation;
> card->reset_jiffies = jiffies;
> schedule_delayed_work(&card->work, 0);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-01 06:03    [W:0.093 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site