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List: linux-omap
Subject: Re: [PATCH] omap: resource: Fix race in register_resource()
From: Mike Chan <mike () android ! com>
Date: 2009-09-30 23:58:19
Message-ID: 8bb80c380909301658v1155ba22ned015b2c59c519b () mail ! gmail ! com
[Download RAW message or body]
On Wed, Sep 30, 2009 at 4:49 PM, Kevin Hilman
<khilman@deeprootsystems.com> wrote:
> Mike Chan <mike@android.com> writes:
>
>> Checking if the resource is already registered and adding to the list
>> must be atomic or bad things can happen.
>>
>> Signed-off-by: Mike Chan <mike@android.com>
>> ---
>> arch/arm/plat-omap/resource.c | 13 ++++++++-----
>> 1 files changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/resource.c b/arch/arm/plat-omap/resource.c
>> index 111020a..4631912 100644
>> --- a/arch/arm/plat-omap/resource.c
>> +++ b/arch/arm/plat-omap/resource.c
>> @@ -255,6 +255,7 @@ int resource_refresh(void)
>> */
>> int resource_register(struct shared_resource *resp)
>> {
>> + int ret = 0;
>> if (!resp)
>> return -EINVAL;
>>
>> @@ -262,12 +263,13 @@ int resource_register(struct shared_resource *resp)
>> return -EINVAL;
>>
>> /* Verify that the resource is not already registered */
>> - if (resource_lookup(resp->name))
>> - return -EEXIST;
>> + down(&res_mutex);
>> + if (_resource_lookup(resp->name))
>> + ret = -EEXIST;
>> + goto out;
>
> Ahem, you're rebased version has a little problem. Missing {} block
> mans this goto is always executed and no resources are ever added.
>
> I'll fix this up manually before applying, but some more testing next
> time would be helpful
>
Opps, sorry about that :/ and thanks for cleaning it up.
-- Mike
> Thanks,
>
> Kevin
>
>
>> INIT_LIST_HEAD(&resp->users_list);
>>
>> - down(&res_mutex);
>> /* Add the resource to the resource list */
>> list_add(&resp->node, &res_list);
>>
>> @@ -275,10 +277,11 @@ int resource_register(struct shared_resource *resp)
>> if (resp->ops->init)
>> resp->ops->init(resp);
>>
>> - up(&res_mutex);
>> pr_debug("resource: registered %s\n", resp->name);
>>
>> - return 0;
>> +out:
>> + up(&res_mutex);
>> + return ret;
>> }
>> EXPORT_SYMBOL(resource_register);
>>
>> --
>> 1.5.4.5
>
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