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SubjectRe: [PATCH] lightnvm: pblk: avoid ref warning on cache creation
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On 11/23/2018 11:04 AM, Hans Holmberg wrote:
> Great catch Javier! Nice refactoring work too.
>
> Reviewed-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
> On Thu, Nov 22, 2018 at 2:47 PM Javier González <javier@javigon.com> wrote:
>>
>> The current kref implementation around pblk global caches triggers a
>> false positive on refcount_inc_checked() (when called) as the kref is
>> initialized to 0. Instead of usint kref_inc() on a 0 reference, which is
>> in principle correct, use kref_init() to avoid the check. This is also
>> more explicit about what actually happens on cache creation.
>>
>> In the process, do a small refactoring to use kref helpers.
>>
>> Signed-off-by: Javier González <javier@cnexlabs.com>
>> ---
>> drivers/lightnvm/pblk-init.c | 14 +++++---------
>> 1 file changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
>> index 13822594647c..e225bd60cbb4 100644
>> --- a/drivers/lightnvm/pblk-init.c
>> +++ b/drivers/lightnvm/pblk-init.c
>> @@ -350,23 +350,19 @@ static int pblk_create_global_caches(void)
>>
>> static int pblk_get_global_caches(void)
>> {
>> - int ret;
>> + int ret = 0;
>>
>> mutex_lock(&pblk_caches.mutex);
>>
>> - if (kref_read(&pblk_caches.kref) > 0) {
>> - kref_get(&pblk_caches.kref);
>> - mutex_unlock(&pblk_caches.mutex);
>> - return 0;
>> - }
>> + if (kref_get_unless_zero(&pblk_caches.kref))
>> + goto out;
>>
>> ret = pblk_create_global_caches();
>> -
>> if (!ret)
>> - kref_get(&pblk_caches.kref);
>> + kref_init(&pblk_caches.kref);
>>
>> +out:
>> mutex_unlock(&pblk_caches.mutex);
>> -
>> return ret;
>> }
>>
>> --
>> 2.7.4
>>

Picked up for 4.21.

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